Solver: Pair conflict set variables with more information about confl…

…icts.

Closes #4805.

This commit adds a solver optimization to skip a version of a package if it does
not resolve any of the conflicts encountered in the last version of that package.
It is on by default and is controlled by the flag --fine-grained-conflicts.

Conflict sets allow the solver to skip other versions of a package if that
package wasn't involved in a conflict.  What if the package was involved in a
conflict, but the other versions of the package don't resolve the conflict?  The
solver should be able to skip the other versions in that case, too.  This commit
adds more information about why each variable was added to the conflict set to
make that possible.  The optimization is based on the assumption that the next
version of a package is likely to have similar dependencies and constraints to
the last version that was tried.

Here is an example where --fine-grained-conflicts is more effective than
backjumping alone:

Package A-1.2 depends on B, and all versions of B depend on C. C is not
available in the package index.  Previously, the solver would have had to try
all combinations of versions for A and B until it found a combination that
avoided the dependency on C.  With --fine-grained-conflicts, the solver only
needs to try A-1.2 and each version of B to know that there is no solution for B
at this point in the search tree.  Then the solver can skip A-1.1 if it also
depends on B.  Here is the log:

[__0] trying: A-1.2 (user goal)
[__1] trying: B-5.0 (dependency of A)
[__2] unknown package: C (dependency of B)
[__2] fail (backjumping, conflict set: B, C)
[__1] skipping: B-4.0, B-3.0, B-2.0, B-1.0 (has the same characteristics that caused the previous version to fail: depends on 'C')
[__1] fail (backjumping, conflict set: A, B, C)
[__0] skipping: A-1.1, A-1.0 (has the same characteristics that caused the previous version to fail: depends on 'B')
[__0] trying: A-8.0
[__1] done

This commit changes the type that is used for conflict sets from 'Set (Var QPN)'
to 'Map (Var QPN) (Set Conflict)', where 'Conflict' represents a single conflict
that caused a variable to be added to the conflict set. 'Conflict' currently
handles three types of conflicts, though more could be added in the future:

1. The package excluded a specific version of one of its dependencies.
2. A version of the package was excluded by a constraint from one of its reverse
   dependencies.
3. The package depends on a package that led to conflicts.

'Conflict' also has an 'OtherConflict' data constructor, which covers every
other conflict and can never cause a version to be skipped.

Since conflicts are paired with variables in the conflict set, they propagate up
the search tree using the same logic as conflict sets.  When conflict sets are
unioned, the conflicts for each variable are also unioned.

During backjumping, the solver checks whether each version of a package can be
skipped by looking up the conflicts for its variable in the previous conflict
set (unless it is the first version to be tried).  A version can only be skipped
when it does not resolve any of the previous conflicts.

One important design choice for this optimization was whether the information
that is paired with conflict set variables should be limited to characteristics
of the current package's .cabal file.  For example, when package X has a dependency
"Y >= 1.2 && < 1.3" and the constraint conflicts with Y-1.4, X's conflict could
be described in two ways:

1. (limited to characteristics of X) X has a constraint on Y that is as
   restrictive as ">= 1.2 && < 1.3".
2. (free to reference other packages) X excludes version 1.4 of Y.

Referencing other packages is more powerful because it allows the description of
the conflict to be more precise, which lets the solver skip more versions.  In
the example above, the solver could skip a version of X containing the
dependency "Y >= 1.1 && < 1.2" with the description in (2) but not with the
description in (1).

The downside of referencing other packages is that the logic is more complex.
When the solver skips a version because if doesn't resolve the previous
conflicts, it cannot simply reuse the previous conflict set.  The solver may
need to add more conflicts specific to the version that was skipped.  For
example, when the solver skips the second version of X above, it needs to add a
conflict saying that Y was rejected by the constraint "Y >= 1.1 && < 1.2".

This commit implements the design where conflicts can reference other packages.

Results from running hackage-benchmark on master at
0d4ee7ba30f671fbaa1162c2373abb27c460478a (cabal1) and this branch (cabal2):

Index-state: 2019-12-09T07:37:06Z
Compiler: GHC 8.6.5
Additional benchmark flags: --min-run-time-percentage-difference-to-rerun=10

package                                        result1        result2              mean1       mean2     stddev1     stddev2     speedup
AERN-RnToRm-Plot                               NoInstallPlan  NoInstallPlan       3.516s      3.049s      0.031s      0.028s      1.153
AutoForms                                      NoInstallPlan  NoInstallPlan       8.705s      3.477s      0.054s      0.039s      2.504
BASIC                                          NoInstallPlan  NoInstallPlan       3.073s      2.708s      0.027s      0.028s      1.135
Blobs                                          Solution       Solution            5.037s      3.490s      0.041s      0.036s      1.443
CMCompare                                      NoInstallPlan  NoInstallPlan       4.311s      3.345s      0.030s      0.038s      1.289
CSPM-Interpreter                               NoInstallPlan  NoInstallPlan       3.357s      3.051s      0.025s      0.027s      1.100
CSPM-cspm                                      NoInstallPlan  NoInstallPlan       3.357s      2.910s      0.021s      0.029s      1.153
Cartesian                                      NoInstallPlan  NoInstallPlan       4.080s      3.483s      0.034s      0.024s      1.171
Chart-simple                                   NoInstallPlan  NoInstallPlan       5.062s      3.677s      0.032s      0.033s      1.377
Elm                                            BackjumpLimit  NoInstallPlan      13.716s      4.847s      0.079s      0.026s      2.830
Eternal10Seconds                               NoInstallPlan  NoInstallPlan       2.758s      2.609s      0.046s      0.052s      1.057
Gamgine                                        Solution       Solution            4.336s      3.451s      0.029s      0.030s      1.256
GeBoP                                          Solution       Solution            5.002s      3.780s      0.026s      0.022s      1.323
GenI                                           NoInstallPlan  NoInstallPlan       4.971s      3.213s      0.036s      0.073s      1.547
Graphalyze                                     Solution       Solution            8.627s      4.698s      0.045s      0.035s      1.836
GuiTV                                          BackjumpLimit  NoInstallPlan       8.704s      6.072s      0.059s      0.036s      1.434
HGamer3D                                       NoInstallPlan  NoInstallPlan       3.073s      2.722s      0.022s      0.035s      1.129
HGamer3D-Ogre-Binding                          NoInstallPlan  NoInstallPlan       3.443s      2.787s      0.038s      0.028s      1.235
HGamer3D-SFML-Binding                          NoInstallPlan  NoInstallPlan       3.144s      2.712s      0.023s      0.047s      1.159
HPlot                                          NoInstallPlan  NoInstallPlan       3.337s      2.826s      0.026s      0.022s      1.181
HROOT                                          NoInstallPlan  NoInstallPlan       3.544s      3.168s      0.019s      0.037s      1.119
HROOT-graf                                     NoInstallPlan  NoInstallPlan       3.418s      3.092s      0.035s      0.036s      1.105
HaRe                                           NoInstallPlan  NoInstallPlan       3.599s      2.989s      0.032s      0.026s      1.204
Hieroglyph                                     Solution       Solution            4.089s      3.299s      0.018s      0.019s      1.240
HipmunkPlayground                              Solution       Solution            3.393s      3.002s      0.049s      0.031s      1.130
INblobs                                        BackjumpLimit  NoInstallPlan       6.427s      3.697s      0.035s      0.039s      1.738
JsonGrammar                                    NoInstallPlan  NoInstallPlan       3.080s      2.756s      0.044s      0.035s      1.118
Michelangelo                                   NoInstallPlan  NoInstallPlan       4.511s      3.573s      0.028s      0.035s      1.263
Monaris                                        NoInstallPlan  NoInstallPlan       3.914s      2.966s      0.028s      0.036s      1.319
Nomyx-Language                                 NoInstallPlan  NoInstallPlan       3.295s      2.767s      0.026s      0.028s      1.191
Nomyx-Rules                                    NoInstallPlan  NoInstallPlan       3.273s      2.777s      0.020s      0.031s      1.179
OpenVG                                         Solution       Solution            3.541s      3.092s      0.021s      0.021s      1.145
QuickPlot                                      NoInstallPlan  NoInstallPlan       3.672s      3.210s      0.023s      0.023s      1.144
SourceGraph                                    NoInstallPlan  NoInstallPlan       6.356s      4.533s      0.049s      0.056s      1.402
Spock-auth                                     Solution       Solution            4.613s      4.150s      0.026s      0.030s      1.112
TBC                                            Solution       Solution            3.318s      2.882s      0.012s      0.019s      1.151
WXDiffCtrl                                     NoInstallPlan  NoInstallPlan       4.880s      3.523s      0.025s      0.028s      1.385
WaveFront                                      NoInstallPlan  NoInstallPlan       5.793s      3.746s      0.039s      0.022s      1.547
WxGeneric                                      BackjumpLimit  NoInstallPlan       6.340s      3.612s      0.043s      0.029s      1.755
accelerate-cuda                                NoInstallPlan  NoInstallPlan       6.312s      3.287s      0.040s      0.027s      1.920
acme-everything                                NoInstallPlan  NoInstallPlan       6.252s      5.737s      0.034s      0.050s      1.090
aeson-bson                                     NoInstallPlan  NoInstallPlan       3.411s      2.811s      0.019s      0.022s      1.214
ag-pictgen                                     NoInstallPlan  NoInstallPlan       3.306s      2.743s      0.028s      0.029s      1.205
alga                                           NoInstallPlan  NoInstallPlan       3.290s      2.836s      0.017s      0.032s      1.160
alsa-gui                                       NoInstallPlan  NoInstallPlan       4.237s      3.333s      0.020s      0.028s      1.271
ampersand                                      NoInstallPlan  NoInstallPlan       3.360s      2.949s      0.026s      0.025s      1.139
analyze-client                                 NoInstallPlan  NoInstallPlan       3.395s      2.788s      0.019s      0.025s      1.218
anansi-pandoc                                  Solution       Solution            4.766s      3.869s      0.034s      0.042s      1.232
apiary-clientsession                           NoInstallPlan  NoInstallPlan       4.434s      3.016s      0.029s      0.036s      1.470
apiary-cookie                                  BackjumpLimit  NoInstallPlan       5.106s      2.952s      0.037s      0.026s      1.730
applicative-parsec                             NoInstallPlan  NoInstallPlan       3.429s      2.998s      0.032s      0.034s      1.144
asic                                           NoInstallPlan  NoInstallPlan       3.278s      2.868s      0.024s      0.027s      1.143
asil                                           NoInstallPlan  NoInstallPlan       4.348s      2.991s      0.029s      0.035s      1.454
astview                                        NoInstallPlan  NoInstallPlan       3.317s      2.768s      0.031s      0.037s      1.198
attoparsec-enumerator                          NoInstallPlan  NoInstallPlan       2.952s      2.695s      0.026s      0.013s      1.096
audiovisual                                    NoInstallPlan  NoInstallPlan       3.305s      2.875s      0.028s      0.032s      1.149
aws-configuration-tools                        Solution       Solution            4.445s      3.955s      0.031s      0.029s      1.124
aws-kinesis                                    Solution       Solution            3.995s      3.544s      0.034s      0.024s      1.127
aws-kinesis-client                             Solution       Solution            5.820s      5.270s      0.029s      0.034s      1.104
aws-performance-tests                          NoInstallPlan  NoInstallPlan       4.495s      3.796s      0.032s      0.018s      1.184
azure-servicebus                               BackjumpLimit  NoInstallPlan       6.367s      3.754s      0.049s      0.035s      1.696
babylon                                        Solution       Solution            5.028s      3.652s      0.017s      0.031s      1.377
bamboo                                         BackjumpLimit  NoInstallPlan       9.642s      4.139s      0.074s      0.041s      2.330
bamboo-plugin-highlight                        NoInstallPlan  NoInstallPlan       5.368s      2.933s      0.034s      0.017s      1.830
battleships                                    NoInstallPlan  NoInstallPlan       3.884s      3.155s      0.031s      0.036s      1.231
bein                                           NoInstallPlan  NoInstallPlan       3.652s      3.267s      0.031s      0.021s      1.118
binding-wx                                     Solution       Solution            5.070s      3.630s      0.047s      0.038s      1.397
birch-beer                                     BackjumpLimit  NoInstallPlan       9.469s      4.206s      0.046s      0.032s      2.251
blosum                                         NoInstallPlan  NoInstallPlan       3.354s      2.734s      0.039s      0.025s      1.227
bluetile                                       NoInstallPlan  NoInstallPlan       3.593s      3.043s      0.028s      0.041s      1.181
bulmex                                         Solution       Solution            5.087s      4.474s      0.037s      0.031s      1.137
cabal-upload                                   NoInstallPlan  NoInstallPlan       2.930s      2.668s      0.028s      0.024s      1.098
category-extras                                NoInstallPlan  NoInstallPlan       3.417s      2.916s      0.026s      0.020s      1.172
cellrenderer-cairo                             NoInstallPlan  NoInstallPlan       3.168s      2.756s      0.029s      0.038s      1.150
celtchar                                       NoInstallPlan  NoInstallPlan       4.298s      3.373s      0.018s      0.030s      1.274
chu2                                           NoInstallPlan  NoInstallPlan       3.795s      2.825s      0.038s      0.029s      1.343
citeproc-hs-pandoc-filter                      BackjumpLimit  NoInstallPlan      10.445s      4.403s      0.028s      0.022s      2.372
cj-token                                       NoInstallPlan  NoInstallPlan       4.258s      3.235s      0.034s      0.059s      1.316
claferwiki                                     NoInstallPlan  NoInstallPlan       5.508s      4.316s      0.027s      0.029s      1.276
clash-systemverilog                            Solution       Solution            7.246s      4.862s      0.050s      0.033s      1.490
clash-verilog                                  Solution       Solution            7.218s      4.853s      0.058s      0.038s      1.487
clash-vhdl                                     Solution       Solution            7.227s      4.853s      0.036s      0.039s      1.489
clckwrks-dot-com                               BackjumpLimit  NoInstallPlan       9.000s      4.187s      0.041s      0.033s      2.150
clckwrks-plugin-bugs                           NoInstallPlan  NoInstallPlan       3.190s      2.742s      0.023s      0.012s      1.163
clckwrks-theme-bootstrap                       NoInstallPlan  NoInstallPlan       4.882s      4.353s      0.037s      0.024s      1.121
clckwrks-theme-clckwrks                        NoInstallPlan  NoInstallPlan       4.525s      3.967s      0.026s      0.023s      1.141
clustertools                                   NoInstallPlan  NoInstallPlan       3.039s      2.764s      0.033s      0.037s      1.100
codex                                          Solution       Solution            4.980s      4.430s      0.030s      0.020s      1.124
combinator-interactive                         NoInstallPlan  NoInstallPlan       4.495s      3.131s      0.021s      0.023s      1.435
computational-algebra                          NoInstallPlan  NoInstallPlan       4.601s      3.233s      0.063s      0.018s      1.423
concraft-pl                                    BackjumpLimit  NoInstallPlan       9.683s      5.402s      0.053s      0.031s      1.793
containers-benchmark                           NoInstallPlan  NoInstallPlan       3.651s      2.688s      0.011s      0.029s      1.358
cqrs-example                                   NoInstallPlan  NoInstallPlan       3.295s      2.849s      0.041s      0.030s      1.157
csv-enumerator                                 NoInstallPlan  NoInstallPlan       4.344s      2.742s      0.034s      0.026s      1.584
darcsden                                       NoInstallPlan  NoInstallPlan       6.133s      4.395s      0.038s      0.038s      1.395
data-object-yaml                               Unbuildable    Unbuildable         3.579s      2.921s      0.025s      0.024s      1.225
dephd                                          NoInstallPlan  NoInstallPlan       3.041s      2.763s      0.020s      0.024s      1.101
diagrams-wx                                    NoInstallPlan  NoInstallPlan       3.297s      2.905s      0.020s      0.041s      1.135
dialog                                         NoInstallPlan  NoInstallPlan       4.014s      3.061s      0.032s      0.046s      1.311
digestive-functors-scotty                      BackjumpLimit  Solution            6.666s      3.443s      0.026s      0.030s      1.936
dingo-core                                     NoInstallPlan  NoInstallPlan       3.406s      2.821s      0.032s      0.043s      1.207
distribution-plot                              NoInstallPlan  NoInstallPlan       3.446s      3.102s      0.026s      0.017s      1.111
diversity                                      BackjumpLimit  NoInstallPlan       6.946s      3.222s      0.034s      0.030s      2.156
dow                                            Solution       Solution            3.260s      2.950s      0.049s      0.028s      1.105
dwarfadt                                       Solution       Solution            4.500s      4.010s      0.061s      0.030s      1.122
effect-handlers                                NoInstallPlan  NoInstallPlan       3.400s      2.982s      0.031s      0.025s      1.140
elm-get                                        BackjumpLimit  NoInstallPlan      14.550s      6.523s      0.060s      0.026s      2.231
elm-reactor                                    NoInstallPlan  NoInstallPlan       4.722s      3.177s      0.021s      0.034s      1.486
elm-repl                                       BackjumpLimit  NoInstallPlan      13.642s      5.149s      0.049s      0.028s      2.649
elm-server                                     BackjumpLimit  NoInstallPlan      11.681s      7.027s      0.020s      0.031s      1.662
enumerator-fd                                  NoInstallPlan  NoInstallPlan       3.304s      2.757s      0.021s      0.033s      1.198
eventful-postgresql                            Solution       Solution            4.152s      3.538s      0.042s      0.025s      1.174
eventful-sqlite                                Solution       Solution            4.069s      3.386s      0.038s      0.038s      1.202
ez-couch                                       Solution       Solution            4.356s      3.634s      0.024s      0.020s      1.199
family-tree                                    Solution       Solution            4.573s      3.522s      0.048s      0.018s      1.298
fasta                                          NoInstallPlan  NoInstallPlan       4.754s      2.925s      0.028s      0.031s      1.625
fb-persistent                                  BackjumpLimit  NoInstallPlan      14.438s      3.909s      0.088s      0.033s      3.693
festung                                        NoInstallPlan  NoInstallPlan       9.126s      3.914s      0.048s      0.027s      2.332
fibon                                          NoInstallPlan  NoInstallPlan       2.856s      2.593s      0.031s      0.048s      1.102
filesystem-enumerator                          NoInstallPlan  NoInstallPlan       3.198s      2.762s      0.019s      0.023s      1.158
forml                                          NoInstallPlan  NoInstallPlan       9.324s      5.014s      0.039s      0.052s      1.859
foscam-sort                                    NoInstallPlan  NoInstallPlan       4.178s      3.306s      0.013s      0.039s      1.264
fpco-api                                       BackjumpLimit  Solution           12.008s      6.003s      0.053s      0.025s      2.000
geek-server                                    NoInstallPlan  NoInstallPlan       8.774s      3.491s      0.041s      0.020s      2.513
geni-gui                                       NoInstallPlan  NoInstallPlan       6.212s      3.488s      0.027s      0.018s      1.781
ghc-vis                                        NoInstallPlan  NoInstallPlan       3.731s      3.203s      0.021s      0.021s      1.165
ghcjs-dom-hello                                Solution       Solution            7.211s      6.613s      0.122s      0.179s      1.090
ghcjs-dom-webkit                               NoInstallPlan  NoInstallPlan       3.717s      3.343s      0.034s      0.031s      1.112
ghclive                                        NoInstallPlan  NoInstallPlan       6.898s      3.761s      0.043s      0.032s      1.834
github-backup                                  BackjumpLimit  Solution            9.061s      4.806s      0.040s      0.039s      1.885
gmndl                                          NoInstallPlan  NoInstallPlan       4.953s      3.935s      0.035s      0.032s      1.259
gnome-desktop                                  NoInstallPlan  NoInstallPlan       3.154s      2.730s      0.039s      0.031s      1.155
goal-core                                      NoInstallPlan  NoInstallPlan       3.947s      3.474s      0.028s      0.018s      1.136
google-drive                                   BackjumpLimit  NoInstallPlan       6.119s      3.896s      0.032s      0.042s      1.571
gps2htmlReport                                 Solution       Solution            4.577s      4.126s      0.051s      0.041s      1.109
graphicstools                                  NoInstallPlan  NoInstallPlan       4.915s      3.174s      0.025s      0.047s      1.549
gruff                                          NoInstallPlan  NoInstallPlan       3.891s      3.281s      0.032s      0.035s      1.186
gtk-mac-integration                            NoInstallPlan  NoInstallPlan       3.343s      2.952s      0.016s      0.023s      1.132
gtk2hs-cast-glade                              NoInstallPlan  NoInstallPlan       3.097s      2.760s      0.021s      0.022s      1.122
gtk2hs-cast-gnomevfs                           NoInstallPlan  NoInstallPlan       3.038s      2.702s      0.039s      0.025s      1.124
gtk2hs-cast-gtkglext                           NoInstallPlan  NoInstallPlan       3.421s      2.962s      0.029s      0.040s      1.155
gtk2hs-cast-gtksourceview2                     NoInstallPlan  NoInstallPlan       3.947s      3.117s      0.031s      0.028s      1.267
gtk3-mac-integration                           NoInstallPlan  NoInstallPlan       3.488s      2.983s      0.025s      0.037s      1.170
gtkrsync                                       NoInstallPlan  NoInstallPlan       3.226s      2.776s      0.016s      0.038s      1.162
hack-handler-evhttp                            BackjumpLimit  NoInstallPlan       5.497s      3.269s      0.040s      0.016s      1.682
hack-handler-simpleserver                      NoInstallPlan  NoInstallPlan       3.699s      2.999s      0.017s      0.017s      1.233
hack-middleware-cleanpath                      NoInstallPlan  NoInstallPlan       3.359s      2.918s      0.022s      0.017s      1.151
hack-middleware-clientsession                  NoInstallPlan  NoInstallPlan       3.297s      2.903s      0.034s      0.022s      1.136
hack-middleware-jsonp                          NoInstallPlan  NoInstallPlan       3.350s      2.794s      0.016s      0.021s      1.199
hack2-handler-happstack-server                 NoInstallPlan  NoInstallPlan       3.317s      2.741s      0.022s      0.017s      1.210
hails                                          Solution       Solution            6.896s      4.685s      0.046s      0.030s      1.472
hakyll-blaze-templates                         NoInstallPlan  NoInstallPlan       3.205s      2.815s      0.033s      0.015s      1.139
hakyll-contrib-elm                             Solution       Solution            8.337s      6.351s      0.063s      0.030s      1.313
hakyll-ogmarkup                                BackjumpLimit  NoInstallPlan      16.596s      4.848s      0.057s      0.052s      3.423
halipeto                                       Solution       Solution            3.868s      4.575s      0.047s      0.018s      0.845
happindicator                                  NoInstallPlan  NoInstallPlan       3.122s      2.723s      0.045s      0.034s      1.147
happs-tutorial                                 NoInstallPlan  NoInstallPlan       3.653s      2.846s      0.023s      0.028s      1.284
happstack                                      BackjumpLimit  NoInstallPlan       6.011s      3.000s      0.030s      0.032s      2.004
happstack-clientsession                        BackjumpLimit  NoInstallPlan       7.294s      3.242s      0.026s      0.019s      2.250
happstack-data                                 NoInstallPlan  NoInstallPlan       3.156s      2.791s      0.030s      0.025s      1.131
happstack-dlg                                  Solution       Solution            3.289s      2.886s      0.022s      0.027s      1.140
happstack-facebook                             NoInstallPlan  NoInstallPlan       3.560s      2.822s      0.024s      0.040s      1.261
happstack-hamlet                               BackjumpLimit  NoInstallPlan       6.364s      3.425s      0.023s      0.022s      1.858
happstack-heist                                BackjumpLimit  NoInstallPlan       5.232s      2.974s      0.033s      0.020s      1.759
happstack-helpers                              NoInstallPlan  NoInstallPlan       4.138s      2.972s      0.034s      0.034s      1.393
happstack-hstringtemplate                      BackjumpLimit  NoInstallPlan       5.636s      3.080s      0.027s      0.023s      1.830
happstack-lite                                 BackjumpLimit  NoInstallPlan       7.494s      3.648s      0.044s      0.024s      2.054
happstack-server-tls-cryptonite                BackjumpLimit  NoInstallPlan       8.341s      3.788s      0.040s      0.023s      2.202
haskell-pdf-presenter                          NoInstallPlan  NoInstallPlan       3.254s      2.737s      0.014s      0.024s      1.189
haskellscrabble                                NoInstallPlan  NoInstallPlan       4.524s      2.918s      0.025s      0.025s      1.550
haste-perch                                    NoInstallPlan  NoInstallPlan       3.711s      3.244s      0.021s      0.024s      1.144
hawitter                                       NoInstallPlan  NoInstallPlan       3.288s      2.810s      0.025s      0.047s      1.170
hbro                                           NoInstallPlan  NoInstallPlan       8.560s      4.254s      0.067s      0.078s      2.012
hbro-contrib                                   NoInstallPlan  NoInstallPlan       6.557s      4.295s      0.039s      0.024s      1.527
heatitup-complete                              NoInstallPlan  NoInstallPlan       3.143s      2.731s      0.023s      0.035s      1.151
hedgehog-checkers-lens                         NoInstallPlan  NoInstallPlan       3.861s      2.900s      0.032s      0.016s      1.331
hellage                                        BackjumpLimit  NoInstallPlan       5.914s      2.990s      0.029s      0.036s      1.978
hellnet                                        NoInstallPlan  NoInstallPlan       4.260s      2.909s      0.024s      0.038s      1.465
hermes                                         NoInstallPlan  NoInstallPlan       5.062s      3.265s      0.032s      0.023s      1.550
hesh                                           NoInstallPlan  NoInstallPlan       4.225s      3.286s      0.031s      0.029s      1.286
hfiar                                          NoInstallPlan  NoInstallPlan       6.268s      3.140s      0.034s      0.051s      1.996
hissmetrics                                    NoInstallPlan  NoInstallPlan       3.089s      2.768s      0.058s      0.028s      1.116
hist-pl                                        NoInstallPlan  NoInstallPlan       3.379s      2.816s      0.028s      0.027s      1.200
hledger-chart                                  NoInstallPlan  NoInstallPlan       3.162s      2.732s      0.039s      0.025s      1.158
hledger-vty                                    NoInstallPlan  NoInstallPlan       3.335s      2.756s      0.067s      0.020s      1.210
hoodle                                         BackjumpLimit  NoInstallPlan      20.758s      5.907s      0.155s      0.033s      3.514
hoodle-core                                    BackjumpLimit  NoInstallPlan      19.462s      5.314s      0.160s      0.085s      3.662
hoodle-publish                                 BackjumpLimit  NoInstallPlan      13.920s      4.536s      0.089s      0.029s      3.069
hoodle-render                                  NoInstallPlan  NoInstallPlan      11.423s      4.392s      0.042s      0.040s      2.601
hpage                                          NoInstallPlan  NoInstallPlan       6.998s      3.458s      0.034s      0.033s      2.024
hplayground                                    BackjumpLimit  NoInstallPlan       7.878s      4.227s      0.044s      0.030s      1.864
hs-pkpass                                      NoInstallPlan  NoInstallPlan       3.191s      2.789s      0.027s      0.030s      1.144
hsignal                                        NoInstallPlan  NoInstallPlan       3.489s      2.854s      0.031s      0.027s      1.223
hspresent                                      Solution       Solution            3.330s      2.799s      0.027s      0.032s      1.190
hstzaar                                        NoInstallPlan  NoInstallPlan       3.422s      2.797s      0.032s      0.029s      1.223
http-client-lens                               NoInstallPlan  NoInstallPlan       3.381s      2.940s      0.023s      0.042s      1.150
http-client-session                            NoInstallPlan  NoInstallPlan       3.241s      2.919s      0.036s      0.025s      1.110
hums                                           NoInstallPlan  NoInstallPlan       3.899s      3.336s      0.031s      0.030s      1.169
hunt-server                                    NoInstallPlan  NoInstallPlan       3.311s      2.909s      0.021s      0.029s      1.138
hxournal                                       BackjumpLimit  NoInstallPlan       6.425s      3.054s      0.073s      0.033s      2.104
hyakko                                         Solution       Solution            4.903s      3.872s      0.024s      0.021s      1.266
hyperpublic                                    NoInstallPlan  NoInstallPlan       2.755s      2.565s      0.032s      0.039s      1.074
i3blocks-hs-contrib                            NoInstallPlan  NoInstallPlan       3.391s      2.958s      0.023s      0.023s      1.146
ideas-math                                     NoInstallPlan  NoInstallPlan       3.040s      2.734s      0.021s      0.024s      1.112
imprevu-happstack                              NoInstallPlan  NoInstallPlan       3.456s      3.076s      0.024s      0.037s      1.123
instapaper-sender                              Solution       Solution            4.099s      3.635s      0.037s      0.015s      1.128
iptadmin                                       BackjumpLimit  NoInstallPlan       5.964s      3.152s      0.037s      0.050s      1.892
isotope                                        Solution       Solution            3.284s      2.856s      0.032s      0.031s      1.150
jbi                                            Solution       Solution            3.387s      3.076s      0.026s      0.013s      1.101
jsaddle-hello                                  NoInstallPlan  NoInstallPlan       3.635s      3.209s      0.041s      0.029s      1.133
json-pointer-hasql                             NoInstallPlan  NoInstallPlan       6.663s      3.385s      0.036s      0.020s      1.968
kawaii                                         Solution       Solution            8.740s      5.624s      0.025s      0.028s      1.554
keera-hails-reactive-wx                        Solution       Solution            5.056s      3.656s      0.032s      0.023s      1.383
kevin                                          NoInstallPlan  NoInstallPlan       3.316s      2.783s      0.030s      0.027s      1.191
lambdabot-xmpp                                 Solution       Solution            6.170s      5.441s      0.038s      0.034s      1.134
lambdacube-bullet                              Solution       Solution            3.396s      3.114s      0.037s      0.051s      1.090
lambdacube-engine                              Solution       Solution            3.322s      2.973s      0.020s      0.027s      1.117
lambdiff                                       NoInstallPlan  NoInstallPlan       3.804s      2.906s      0.024s      0.037s      1.309
language-ninja                                 NoInstallPlan  NoInstallPlan       3.051s      2.711s      0.061s      0.029s      1.125
language-spelling                              NoInstallPlan  NoInstallPlan       3.232s      2.768s      0.025s      0.025s      1.168
layers-game                                    Solution       Solution            3.797s      3.279s      0.027s      0.042s      1.158
leaky                                          NoInstallPlan  NoInstallPlan       3.668s      2.997s      0.030s      0.037s      1.224
leksah                                         NoInstallPlan  NoInstallPlan       4.632s      3.379s      0.036s      0.039s      1.371
lhc                                            NoInstallPlan  NoInstallPlan       3.148s      2.876s      0.063s      0.033s      1.095
list-t-attoparsec                              NoInstallPlan  NoInstallPlan       3.583s      3.129s      0.020s      0.029s      1.145
list-t-html-parser                             NoInstallPlan  NoInstallPlan       3.721s      3.011s      0.025s      0.023s      1.236
liveplot                                       NoInstallPlan  NoInstallPlan       3.542s      2.826s      0.024s      0.036s      1.253
llvm-general                                   NoInstallPlan  NoInstallPlan       3.325s      3.058s      0.028s      0.024s      1.087
log                                            BackjumpLimit  Solution            7.669s      4.420s      0.039s      0.026s      1.735
loli                                           BackjumpLimit  NoInstallPlan       5.683s      2.835s      0.024s      0.028s      2.004
lsystem                                        BackjumpLimit  NoInstallPlan       6.314s      3.683s      0.043s      0.023s      1.714
maid                                           NoInstallPlan  NoInstallPlan       4.421s      2.859s      0.024s      0.027s      1.547
manatee                                        NoInstallPlan  NoInstallPlan       5.418s      3.353s      0.021s      0.035s      1.616
manatee-all                                    NoInstallPlan  NoInstallPlan       3.651s      3.139s      0.022s      0.033s      1.163
manatee-browser                                NoInstallPlan  NoInstallPlan       3.275s      2.855s      0.033s      0.020s      1.147
manatee-curl                                   NoInstallPlan  NoInstallPlan       3.341s      2.826s      0.048s      0.036s      1.182
manatee-editor                                 NoInstallPlan  NoInstallPlan       3.577s      2.843s      0.023s      0.025s      1.258
manatee-filemanager                            NoInstallPlan  NoInstallPlan       3.685s      2.804s      0.021s      0.013s      1.314
manatee-imageviewer                            NoInstallPlan  NoInstallPlan       3.698s      2.835s      0.019s      0.030s      1.304
manatee-mplayer                                NoInstallPlan  NoInstallPlan       3.136s      2.794s      0.021s      0.025s      1.122
manatee-pdfviewer                              NoInstallPlan  NoInstallPlan       3.458s      2.828s      0.036s      0.029s      1.223
manatee-reader                                 NoInstallPlan  NoInstallPlan       3.283s      2.813s      0.026s      0.020s      1.167
manatee-terminal                               NoInstallPlan  NoInstallPlan       3.153s      2.764s      0.023s      0.037s      1.141
mangopay                                       NoInstallPlan  NoInstallPlan       3.226s      2.896s      0.028s      0.029s      1.114
markup-preview                                 NoInstallPlan  NoInstallPlan       4.598s      3.678s      0.024s      0.052s      1.250
matlab                                         NoInstallPlan  NoInstallPlan       3.323s      2.793s      0.023s      0.037s      1.190
matsuri                                        NoInstallPlan  NoInstallPlan       3.537s      2.791s      0.032s      0.030s      1.268
mdcat                                          NoInstallPlan  NoInstallPlan       4.085s      2.954s      0.036s      0.038s      1.383
mediabus-fdk-aac                               BackjumpLimit  NoInstallPlan      10.903s      4.132s      0.049s      0.018s      2.639
mellon-web                                     NoInstallPlan  NoInstallPlan       7.345s      3.736s      0.017s      0.034s      1.966
messente                                       NoInstallPlan  NoInstallPlan       4.698s      3.269s      0.021s      0.035s      1.437
micrologger                                    NoInstallPlan  NoInstallPlan       3.700s      3.296s      0.038s      0.041s      1.123
midimory                                       NoInstallPlan  NoInstallPlan       5.143s      3.483s      0.054s      0.028s      1.476
minesweeper                                    NoInstallPlan  NoInstallPlan       3.414s      2.836s      0.024s      0.018s      1.204
modify-fasta                                   NoInstallPlan  NoInstallPlan       4.678s      2.791s      0.027s      0.017s      1.676
mongodb-queue                                  BackjumpLimit  Solution            7.015s      3.780s      0.044s      0.031s      1.856
monoids                                        NoInstallPlan  NoInstallPlan       3.918s      2.805s      0.029s      0.042s      1.397
music-parts                                    Solution       Solution            3.962s      3.598s      0.028s      0.035s      1.101
music-util                                     NoInstallPlan  NoInstallPlan       4.276s      2.983s      0.023s      0.040s      1.433
mxnet-dataiter                                 NoInstallPlan  NoInstallPlan       3.655s      3.231s      0.041s      0.032s      1.131
netease-fm                                     Solution       Solution            3.526s      3.079s      0.019s      0.031s      1.145
nomyx-language                                 NoInstallPlan  NoInstallPlan       3.482s      3.074s      0.030s      0.045s      1.133
notmuch-web                                    BackjumpLimit  NoInstallPlan      14.552s      5.956s      0.046s      0.047s      2.443
null-canvas                                    NoInstallPlan  NoInstallPlan       4.468s      2.938s      0.031s      0.033s      1.521
nymphaea                                       NoInstallPlan  NoInstallPlan       3.258s      2.794s      0.020s      0.035s      1.166
orchestrate                                    BackjumpLimit  Solution           11.511s      5.146s      0.068s      0.045s      2.237
ot                                             NoInstallPlan  NoInstallPlan       3.152s      2.862s      0.059s      0.038s      1.101
panda                                          BackjumpLimit  Solution           10.148s      5.647s      0.047s      0.039s      1.797
paypal-api                                     NoInstallPlan  NoInstallPlan       3.297s      2.844s      0.014s      0.037s      1.159
pdf-slave-server                               NoInstallPlan  NoInstallPlan       3.578s      3.197s      0.018s      0.048s      1.119
perceptual-hash                                Solution       Solution            5.804s      3.876s      0.043s      0.023s      1.498
persistent-protobuf                            Solution       Solution            4.072s      3.175s      0.027s      0.036s      1.283
pgdl                                           Solution       Solution            4.226s      3.682s      0.023s      0.021s      1.148
phooey                                         BackjumpLimit  NoInstallPlan       8.662s      4.400s      0.046s      0.039s      1.969
pinpon                                         NoInstallPlan  NoInstallPlan       5.546s      4.047s      0.052s      0.018s      1.371
pipes-conduit                                  NoInstallPlan  NoInstallPlan       2.804s      2.671s      0.026s      0.044s      1.050
pipes-transduce                                NoInstallPlan  NoInstallPlan       3.665s      2.876s      0.022s      0.019s      1.274
planet-mitchell                                NoInstallPlan  NoInstallPlan       4.629s      3.785s      0.016s      0.029s      1.223
plot-gtk                                       NoInstallPlan  NoInstallPlan       4.754s      2.916s      0.019s      0.018s      1.630
plot-gtk3                                      NoInstallPlan  NoInstallPlan       3.439s      2.987s      0.026s      0.018s      1.151
pontarius-mediaserver                          NoInstallPlan  NoInstallPlan       3.308s      2.873s      0.064s      0.016s      1.152
pontarius-xpmn                                 NoInstallPlan  NoInstallPlan       3.389s      2.905s      0.028s      0.017s      1.167
poppler                                        NoInstallPlan  NoInstallPlan       3.933s      3.420s      0.036s      0.031s      1.150
portager                                       NoInstallPlan  NoInstallPlan       3.512s      3.100s      0.032s      0.042s      1.133
postgrest-ws                                   BackjumpLimit  NoInstallPlan      11.707s      4.717s      0.089s      0.045s      2.482
primula-bot                                    NoInstallPlan  NoInstallPlan       3.676s      2.886s      0.023s      0.034s      1.274
printcess                                      NoInstallPlan  NoInstallPlan       3.957s      3.137s      0.025s      0.037s      1.261
process-streaming                              NoInstallPlan  NoInstallPlan       4.727s      3.392s      0.040s      0.027s      1.393
proplang                                       NoInstallPlan  NoInstallPlan       3.375s      2.835s      0.043s      0.042s      1.191
purescript-tsd-gen                             Solution       Solution            4.792s      4.273s      0.038s      0.032s      1.121
push-notify                                    BackjumpLimit  NoInstallPlan       9.536s      4.017s      0.046s      0.033s      2.374
pushme                                         Solution       Solution            8.693s      4.317s      0.030s      0.025s      2.014
quickbooks                                     NoInstallPlan  NoInstallPlan       6.061s      3.346s      0.016s      0.034s      1.811
quiver-http                                    NoInstallPlan  NoInstallPlan       3.405s      3.042s      0.030s      0.028s      1.119
rail-compiler-editor                           NoInstallPlan  NoInstallPlan       7.381s      2.987s      0.027s      0.022s      2.471
rasa-ext-slate                                 Solution       Solution            3.755s      3.351s      0.032s      0.026s      1.121
react-haskell                                  NoInstallPlan  NoInstallPlan       5.053s      3.391s      0.023s      0.032s      1.490
reactive                                       Solution       Solution            4.323s      2.926s      0.029s      0.029s      1.477
reactive-banana-wx                             NoInstallPlan  NoInstallPlan       5.913s      3.508s      0.049s      0.022s      1.686
reactive-fieldtrip                             BackjumpLimit  NoInstallPlan       6.739s      3.095s      0.028s      0.045s      2.177
reactive-glut                                  BackjumpLimit  NoInstallPlan       6.486s      2.890s      0.036s      0.026s      2.244
reflex-dom-colonnade                           Solution       Solution            7.034s      6.734s      0.194s      0.190s      1.045
remote-json-server                             NoInstallPlan  NoInstallPlan       3.614s      3.016s      0.043s      0.036s      1.198
rest-client                                    NoInstallPlan  NoInstallPlan       3.268s      2.909s      0.027s      0.025s      1.123
restful-snap                                   NoInstallPlan  NoInstallPlan       3.956s      3.476s      0.035s      0.028s      1.138
rhythm-game-tutorial                           NoInstallPlan  NoInstallPlan       3.855s      3.300s      0.027s      0.016s      1.168
rob                                            Solution       Solution            3.754s      3.389s      0.024s      0.034s      1.108
roguestar-gl                                   NoInstallPlan  NoInstallPlan       3.305s      2.762s      0.027s      0.048s      1.197
route-generator                                NoInstallPlan  NoInstallPlan       3.435s      2.731s      0.040s      0.014s      1.258
rsagl-frp                                      NoInstallPlan  NoInstallPlan       3.306s      2.854s      0.039s      0.010s      1.158
scotty-rest                                    Solution       Solution            4.081s      3.504s      0.031s      0.045s      1.165
semdoc                                         NoInstallPlan  NoInstallPlan       4.163s      3.529s      0.018s      0.033s      1.179
seqloc-datafiles                               NoInstallPlan  NoInstallPlan       4.364s      3.127s      0.054s      0.028s      1.395
servant-auth-cookie                            NoInstallPlan  NoInstallPlan       3.296s      2.934s      0.019s      0.020s      1.123
servant-auth-swagger                           Solution       Solution            3.772s      3.460s      0.025s      0.024s      1.090
servant-auth-token                             NoInstallPlan  NoInstallPlan       4.191s      3.607s      0.029s      0.022s      1.162
servant-auth-token-leveldb                     NoInstallPlan  NoInstallPlan       4.018s      3.612s      0.022s      0.033s      1.112
servant-examples                               BackjumpLimit  NoInstallPlan      12.497s      3.746s      0.059s      0.039s      3.336
serversession-frontend-yesod                   NoInstallPlan  NoInstallPlan       3.050s      2.810s      0.029s      0.037s      1.086
sgrep                                          NoInstallPlan  NoInstallPlan       3.000s      2.716s      0.021s      0.025s      1.104
shuffle                                        NoInstallPlan  NoInstallPlan       3.196s      2.863s      0.019s      0.035s      1.116
simpleprelude                                  NoInstallPlan  NoInstallPlan       2.788s      2.601s      0.030s      0.062s      1.072
slidemews                                      NoInstallPlan  NoInstallPlan       3.108s      2.808s      0.027s      0.037s      1.107
smtps-gmail                                    NoInstallPlan  NoInstallPlan       3.327s      2.962s      0.030s      0.028s      1.123
snap-auth-cli                                  NoInstallPlan  NoInstallPlan       3.978s      3.310s      0.037s      0.029s      1.202
snap-elm                                       BackjumpLimit  NoInstallPlan      12.454s      4.631s      0.052s      0.020s      2.690
snap-web-routes                                NoInstallPlan  NoInstallPlan       3.382s      2.973s      0.028s      0.030s      1.137
snaplet-acid-state                             NoInstallPlan  NoInstallPlan       3.487s      2.913s      0.021s      0.017s      1.197
snaplet-actionlog                              NoInstallPlan  NoInstallPlan       4.142s      3.330s      0.019s      0.031s      1.244
snaplet-coffee                                 NoInstallPlan  NoInstallPlan       4.566s      3.543s      0.036s      0.032s      1.289
snaplet-css-min                                NoInstallPlan  NoInstallPlan       5.301s      2.971s      0.029s      0.020s      1.784
snaplet-customauth                             NoInstallPlan  NoInstallPlan       4.249s      3.591s      0.025s      0.037s      1.183
snaplet-fay                                    NoInstallPlan  NoInstallPlan       3.656s      3.071s      0.033s      0.015s      1.191
snaplet-hasql                                  NoInstallPlan  NoInstallPlan       6.973s      4.184s      0.030s      0.035s      1.666
snaplet-mysql-simple                           NoInstallPlan  NoInstallPlan       3.670s      2.961s      0.024s      0.016s      1.239
snaplet-persistent                             NoInstallPlan  NoInstallPlan       6.576s      4.441s      0.032s      0.032s      1.481
snaplet-redson                                 NoInstallPlan  NoInstallPlan       2.975s      2.701s      0.028s      0.012s      1.101
snaplet-sedna                                  NoInstallPlan  NoInstallPlan       3.784s      4.431s      0.020s      0.035s      0.854
snaplet-sqlite-simple                          NoInstallPlan  NoInstallPlan       3.695s      3.032s      0.046s      0.018s      1.219
socketio                                       NoInstallPlan  NoInstallPlan       3.091s      2.779s      0.032s      0.033s      1.112
soegtk                                         NoInstallPlan  NoInstallPlan       3.315s      3.013s      0.027s      0.019s      1.100
spike                                          NoInstallPlan  NoInstallPlan       3.340s      2.770s      0.028s      0.017s      1.206
ssh-tunnel                                     NoInstallPlan  NoInstallPlan       2.988s      2.749s      0.017s      0.028s      1.087
sssp                                           NoInstallPlan  NoInstallPlan       3.701s      3.209s      0.025s      0.033s      1.153
stack-run-auto                                 NoInstallPlan  NoInstallPlan       5.384s      4.049s      0.025s      0.039s      1.330
stackage                                       BackjumpLimit  Solution            7.417s      4.820s      0.058s      0.044s      1.539
stackage-build-plan                            NoInstallPlan  NoInstallPlan       5.537s      4.026s      0.059s      0.083s      1.375
stackage-types                                 NoInstallPlan  NoInstallPlan       3.482s      2.897s      0.030s      0.029s      1.202
stratux                                        NoInstallPlan  NoInstallPlan      10.506s      4.368s      0.062s      0.038s      2.406
stripe                                         Solution       Solution            3.511s      3.182s      0.044s      0.032s      1.103
sunroof-examples                               NoInstallPlan  NoInstallPlan       3.221s      2.960s      0.025s      0.045s      1.088
t3-client                                      NoInstallPlan  NoInstallPlan       6.026s      3.266s      0.047s      0.022s      1.845
t3-server                                      NoInstallPlan  NoInstallPlan       4.534s      3.273s      0.025s      0.026s      1.385
tamarin-prover-term                            NoInstallPlan  NoInstallPlan       2.810s      2.629s      0.014s      0.053s      1.069
tcache-AWS                                     Solution       Solution            4.669s      3.733s      0.039s      0.037s      1.251
tellbot                                        BackjumpLimit  NoInstallPlan       6.123s      3.330s      0.037s      0.025s      1.839
text-icu-normalized                            Solution       Solution            4.748s      3.629s      0.028s      0.030s      1.308
thumbnail-plus                                 NoInstallPlan  NoInstallPlan       3.221s      2.785s      0.037s      0.017s      1.157
tickle                                         NoInstallPlan  NoInstallPlan       4.934s      3.991s      0.035s      0.019s      1.236
tiger                                          NoInstallPlan  NoInstallPlan       3.066s      2.715s      0.050s      0.034s      1.129
tightrope                                      Solution       Solution            4.995s      4.069s      0.031s      0.032s      1.227
tighttp                                        NoInstallPlan  NoInstallPlan       3.903s      2.739s      0.030s      0.039s      1.425
tkyprof                                        BackjumpLimit  Solution           13.516s      5.429s      0.082s      0.042s      2.490
toktok                                         NoInstallPlan  NoInstallPlan       3.373s      2.883s      0.014s      0.038s      1.170
too-many-cells                                 BackjumpLimit  NoInstallPlan      10.111s      4.412s      0.054s      0.031s      2.292
travis                                         Solution       Solution            3.419s      3.085s      0.026s      0.024s      1.108
traypoweroff                                   NoInstallPlan  NoInstallPlan       2.839s      2.590s      0.024s      0.050s      1.096
twidge                                         NoInstallPlan  NoInstallPlan       3.424s      2.865s      0.026s      0.022s      1.195
typescript-docs                                NoInstallPlan  NoInstallPlan       3.357s      3.012s      0.035s      0.016s      1.114
unitym-yesod                                   NoInstallPlan  NoInstallPlan       4.123s      3.240s      0.031s      0.028s      1.273
unix-process-conduit                           NoInstallPlan  NoInstallPlan       3.027s      2.762s      0.052s      0.023s      1.096
uri-parse                                      NoInstallPlan  NoInstallPlan       4.532s      3.390s      0.031s      0.028s      1.337
uu-cco-examples                                Solution       Solution            3.172s      2.760s      0.058s      0.041s      1.149
uuagc                                          NoInstallPlan  NoInstallPlan       3.287s      2.718s      0.023s      0.018s      1.209
validate-input                                 NoInstallPlan  NoInstallPlan       5.469s      3.165s      0.043s      0.019s      1.728
verify                                         NoInstallPlan  NoInstallPlan       4.204s      3.193s      0.037s      0.047s      1.317
vtegtk3                                        NoInstallPlan  NoInstallPlan       3.202s      2.967s      0.032s      0.049s      1.079
vty-ui                                         NoInstallPlan  NoInstallPlan       3.656s      2.961s      0.024s      0.029s      1.235
wai-handler-devel                              NoInstallPlan  NoInstallPlan       5.897s      3.232s      0.061s      0.038s      1.825
wai-lite                                       NoInstallPlan  NoInstallPlan       3.107s      2.813s      0.039s      0.026s      1.105
wai-middleware-cache-redis                     NoInstallPlan  NoInstallPlan       3.619s      2.734s      0.018s      0.023s      1.324
wai-middleware-route                           Solution       Solution            3.792s      2.902s      0.027s      0.022s      1.307
wai-throttler                                  NoInstallPlan  NoInstallPlan       3.445s      2.922s      0.019s      0.037s      1.179
warp-dynamic                                   NoInstallPlan  NoInstallPlan       3.040s      2.641s      0.021s      0.033s      1.151
warp-static                                    NoInstallPlan  NoInstallPlan       3.395s      2.790s      0.009s      0.030s      1.217
web-browser-in-haskell                         NoInstallPlan  NoInstallPlan       3.749s      2.971s      0.049s      0.028s      1.262
web-encodings                                  NoInstallPlan  NoInstallPlan       3.118s      2.880s      0.056s      0.042s      1.082
webkit                                         NoInstallPlan  NoInstallPlan       3.840s      3.115s      0.028s      0.057s      1.233
webkitgtk3                                     NoInstallPlan  NoInstallPlan       3.718s      3.098s      0.026s      0.060s      1.200
websnap                                        NoInstallPlan  NoInstallPlan       3.730s      2.962s      0.020s      0.040s      1.259
werewolf                                       Solution       Solution            3.692s      3.286s      0.034s      0.038s      1.124
wobsurv                                        NoInstallPlan  NoInstallPlan       3.292s      2.943s      0.028s      0.040s      1.119
wordchoice                                     Solution       Solution            5.822s      4.729s      0.030s      0.020s      1.231
wx                                             BackjumpLimit  Solution            8.170s      5.570s      0.046s      0.041s      1.467
wxAsteroids                                    BackjumpLimit  Solution            7.319s      3.943s      0.035s      0.022s      1.856
wxFruit                                        Solution       Solution            4.706s      3.691s      0.022s      0.036s      1.275
wxc                                            NoInstallPlan  NoInstallPlan       4.619s      3.004s      0.041s      0.035s      1.538
wxcore                                         Solution       Solution            5.077s      3.650s      0.025s      0.023s      1.391
wxdirect                                       NoInstallPlan  NoInstallPlan       3.605s      3.083s      0.054s      0.028s      1.169
wxhnotepad                                     NoInstallPlan  NoInstallPlan       4.686s      3.422s      0.054s      0.019s      1.369
xdcc                                           NoInstallPlan  NoInstallPlan       3.205s      2.873s      0.021s      0.022s      1.116
xml-pipe                                       NoInstallPlan  NoInstallPlan       3.167s      2.674s      0.016s      0.025s      1.184
xmpipe                                         NoInstallPlan  NoInstallPlan       3.579s      2.746s      0.037s      0.023s      1.303
xournal-render                                 NoInstallPlan  NoInstallPlan       3.638s      2.805s      0.027s      0.022s      1.297
xtc                                            Solution       Solution            5.028s      3.634s      0.034s      0.021s      1.384
yesod-auth-account-fork                        BackjumpLimit  NoInstallPlan       7.659s      3.841s      0.040s      0.060s      1.994
yesod-auth-bcrypt                              NoInstallPlan  NoInstallPlan       8.870s      3.970s      0.042s      0.016s      2.234
yesod-auth-deskcom                             NoInstallPlan  NoInstallPlan       4.654s      3.413s      0.027s      0.047s      1.364
yesod-auth-ldap                                NoInstallPlan  NoInstallPlan       2.996s      2.751s      0.020s      0.024s      1.089
yesod-auth-nopassword                          NoInstallPlan  NoInstallPlan       4.579s      3.880s      0.024s      0.027s      1.180
yesod-auth-zendesk                             NoInstallPlan  NoInstallPlan       4.519s      3.111s      0.029s      0.019s      1.452
yesod-comments                                 BackjumpLimit  NoInstallPlan       6.942s      3.679s      0.046s      0.018s      1.887
yesod-crud                                     NoInstallPlan  NoInstallPlan       3.521s      3.189s      0.034s      0.055s      1.104
yesod-form-richtext                            NoInstallPlan  NoInstallPlan       4.928s      3.741s      0.028s      0.020s      1.317
yesod-goodies                                  NoInstallPlan  NoInstallPlan       3.552s      2.733s      0.038s      0.043s      1.299
yesod-job-queue                                Solution       Solution            7.796s      6.027s      0.063s      0.035s      1.293
yesod-links                                    NoInstallPlan  NoInstallPlan       4.181s      3.117s      0.014s      0.029s      1.341
yesod-lucid                                    NoInstallPlan  NoInstallPlan       3.910s      3.414s      0.026s      0.033s      1.145
yesod-mangopay                                 BackjumpLimit  NoInstallPlan       7.016s      3.461s      0.058s      0.026s      2.027
yesod-paypal-rest                              NoInstallPlan  NoInstallPlan       3.867s      3.387s      0.020s      0.016s      1.142
yesod-platform                                 NoInstallPlan  NoInstallPlan       3.551s      3.159s      0.035s      0.059s      1.124
yesod-pure                                     Solution       Solution            4.620s      3.791s      0.038s      0.037s      1.219
yesod-purescript                               NoInstallPlan  NoInstallPlan       5.426s      3.827s      0.074s      0.027s      1.418
yesod-recaptcha                                BackjumpLimit  NoInstallPlan      15.046s      4.573s      0.085s      0.030s      3.290
yesod-sass                                     NoInstallPlan  NoInstallPlan       3.081s      2.820s      0.026s      0.033s      1.092
yesod-session-redis                            NoInstallPlan  NoInstallPlan       5.285s      3.769s      0.066s      0.022s      1.402
yesod-static-angular                           BackjumpLimit  NoInstallPlan       7.646s      3.549s      0.030s      0.026s      2.155
yesod-tls                                      NoInstallPlan  NoInstallPlan       4.109s      3.256s      0.014s      0.057s      1.262
yesod-vend                                     NoInstallPlan  NoInstallPlan       4.952s      3.769s      0.049s      0.039s      1.314
yi-contrib                                     UnbuildableDep UnbuildableDep      3.663s      2.949s      0.028s      0.032s      1.242
yi-frontend-pango                              NoInstallPlan  NoInstallPlan       3.735s      3.175s      0.034s      0.021s      1.176
z85                                            NoInstallPlan  NoInstallPlan       4.004s      2.927s      0.034s      0.027s      1.368
zephyr                                         Solution       Solution            4.482s      4.189s      0.053s      0.053s      1.070
zeroth                                         Solution       Solution            3.383s      2.866s      0.021s      0.023s      1.180
zifter-stack                                   Solution       Solution            3.338s      3.040s      0.042s      0.035s      1.098
ziptastic-client                               BackjumpLimit  NoInstallPlan      18.042s      4.060s      0.110s      0.034s      4.443
zoom-cache-sndfile                             NoInstallPlan  NoInstallPlan       3.622s      2.844s      0.025s      0.022s      1.274

Cabal/doc/nix-local-build.rst

@@ -2115,6 +2115,23 @@ Most users generally won't need these.
     The command line variant of this field is
     ``--(no-)count-conflicts``.
 
+.. cfg-field:: fine-grained-conflicts: boolean
+               --fine-grained-conflicts
+               --no-fine-grained-conflicts
+    :synopsis: Skip a version of a package if it does not resolve any conflicts
+	       encountered in the last version (solver optimization).
+
+    :default: True
+
+    When enabled, the solver will skip a version of a package if it does not
+    resolve any of the conflicts encountered in the last version of that
+    package. For example, if ``foo-1.2`` depended on ``bar``, and the solver
+    couldn't find consistent versions for ``bar``'s dependencies, then the
+    solver would skip ``foo-1.1`` if it also depended on ``bar``.
+
+    The command line variant of this field is
+    ``--(no-)fine-grained-conflicts``.
+
 .. cfg-field:: minimize-conflict-set: boolean
                --minimize-conflict-set
                --no-minimize-conflict-set

cabal-install/Distribution/Client/Config.hs

@@ -312,6 +312,7 @@ instance Semigroup SavedConfig where
         installMaxBackjumps          = combine installMaxBackjumps,
         installReorderGoals          = combine installReorderGoals,
         installCountConflicts        = combine installCountConflicts,
+        installFineGrainedConflicts  = combine installFineGrainedConflicts,
         installMinimizeConflictSet   = combine installMinimizeConflictSet,
         installIndependentGoals      = combine installIndependentGoals,
         installShadowPkgs            = combine installShadowPkgs,

cabal-install/Distribution/Client/Dependency.hs

@@ -47,6 +47,7 @@ module Distribution.Client.Dependency (
     setPreferenceDefault,
     setReorderGoals,
     setCountConflicts,
+    setFineGrainedConflicts,
     setMinimizeConflictSet,
     setIndependentGoals,
     setAvoidReinstalls,
@@ -159,6 +160,7 @@ data DepResolverParams = DepResolverParams {
        depResolverSourcePkgIndex    :: PackageIndex.PackageIndex UnresolvedSourcePackage,
        depResolverReorderGoals      :: ReorderGoals,
        depResolverCountConflicts    :: CountConflicts,
+       depResolverFineGrainedConflicts :: FineGrainedConflicts,
        depResolverMinimizeConflictSet :: MinimizeConflictSet,
        depResolverIndependentGoals  :: IndependentGoals,
        depResolverAvoidReinstalls   :: AvoidReinstalls,
@@ -197,6 +199,7 @@ showDepResolverParams p =
   ++ "\nstrategy: "          ++ show (depResolverPreferenceDefault        p)
   ++ "\nreorder goals: "     ++ show (asBool (depResolverReorderGoals     p))
   ++ "\ncount conflicts: "   ++ show (asBool (depResolverCountConflicts   p))
+  ++ "\nfine grained conflicts: " ++ show (asBool (depResolverFineGrainedConflicts p))
   ++ "\nminimize conflict set: " ++ show (asBool (depResolverMinimizeConflictSet p))
   ++ "\nindependent goals: " ++ show (asBool (depResolverIndependentGoals p))
   ++ "\navoid reinstalls: "  ++ show (asBool (depResolverAvoidReinstalls  p))
@@ -254,6 +257,7 @@ basicDepResolverParams installedPkgIndex sourcePkgIndex =
        depResolverSourcePkgIndex    = sourcePkgIndex,
        depResolverReorderGoals      = ReorderGoals False,
        depResolverCountConflicts    = CountConflicts True,
+       depResolverFineGrainedConflicts = FineGrainedConflicts True,
        depResolverMinimizeConflictSet = MinimizeConflictSet False,
        depResolverIndependentGoals  = IndependentGoals False,
        depResolverAvoidReinstalls   = AvoidReinstalls False,
@@ -310,6 +314,12 @@ setCountConflicts count params =
       depResolverCountConflicts = count
     }
 
+setFineGrainedConflicts :: FineGrainedConflicts -> DepResolverParams -> DepResolverParams
+setFineGrainedConflicts fineGrained params =
+    params {
+      depResolverFineGrainedConflicts = fineGrained
+    }
+
 setMinimizeConflictSet :: MinimizeConflictSet -> DepResolverParams -> DepResolverParams
 setMinimizeConflictSet minimize params =
     params {
@@ -755,7 +765,8 @@ resolveDependencies platform comp pkgConfigDB solver params =
 
     Step (showDepResolverParams finalparams)
   $ fmap (validateSolverResult platform comp indGoals)
-  $ runSolver solver (SolverConfig reordGoals cntConflicts minimize indGoals noReinstalls
+  $ runSolver solver (SolverConfig reordGoals cntConflicts fineGrained minimize
+                      indGoals noReinstalls
                       shadowing strFlags allowBootLibs onlyConstrained_ maxBkjumps enableBj
                       solveExes order verbosity (PruneAfterFirstSuccess False))
                      platform comp installedPkgIndex sourcePkgIndex
@@ -769,6 +780,7 @@ resolveDependencies platform comp pkgConfigDB solver params =
       sourcePkgIndex
       reordGoals
       cntConflicts
+      fineGrained
       minimize
       indGoals
       noReinstalls
@@ -1015,9 +1027,9 @@ resolveWithoutDependencies :: DepResolverParams
                            -> Either [ResolveNoDepsError] [UnresolvedSourcePackage]
 resolveWithoutDependencies (DepResolverParams targets constraints
                               prefs defpref installedPkgIndex sourcePkgIndex
-                              _reorderGoals _countConflicts _minimizeConflictSet
-                              _indGoals _avoidReinstalls _shadowing _strFlags
-                              _maxBjumps _enableBj _solveExes
+                              _reorderGoals _countConflicts _fineGrained
+                              _minimizeConflictSet _indGoals _avoidReinstalls
+                              _shadowing _strFlags _maxBjumps _enableBj _solveExes
                               _allowBootLibInstalls _onlyConstrained _order _verbosity) =
     collectEithers $ map selectPackage (Set.toList targets)
   where

cabal-install/Distribution/Client/Fetch.hs

@@ -162,6 +162,8 @@ planPackages verbosity comp platform fetchFlags
 
       . setCountConflicts countConflicts
 
+      . setFineGrainedConflicts fineGrainedConflicts
+
       . setMinimizeConflictSet minimizeConflictSet
 
       . setShadowPkgs shadowPkgs
@@ -199,6 +201,7 @@ planPackages verbosity comp platform fetchFlags
 
     reorderGoals     = fromFlag (fetchReorderGoals     fetchFlags)
     countConflicts   = fromFlag (fetchCountConflicts   fetchFlags)
+    fineGrainedConflicts = fromFlag (fetchFineGrainedConflicts fetchFlags)
     minimizeConflictSet = fromFlag (fetchMinimizeConflictSet fetchFlags)
     independentGoals = fromFlag (fetchIndependentGoals fetchFlags)
     shadowPkgs       = fromFlag (fetchShadowPkgs       fetchFlags)

cabal-install/Distribution/Client/Freeze.hs

@@ -175,6 +175,8 @@ planPackages verbosity comp platform mSandboxPkgInfo freezeFlags
 
       . setCountConflicts countConflicts
 
+      . setFineGrainedConflicts fineGrainedConflicts
+
       . setMinimizeConflictSet minimizeConflictSet
 
       . setShadowPkgs shadowPkgs
@@ -207,6 +209,7 @@ planPackages verbosity comp platform mSandboxPkgInfo freezeFlags
 
     reorderGoals     = fromFlag (freezeReorderGoals     freezeFlags)
     countConflicts   = fromFlag (freezeCountConflicts   freezeFlags)
+    fineGrainedConflicts = fromFlag (freezeFineGrainedConflicts freezeFlags)
     minimizeConflictSet = fromFlag (freezeMinimizeConflictSet freezeFlags)
     independentGoals = fromFlag (freezeIndependentGoals freezeFlags)
     shadowPkgs       = fromFlag (freezeShadowPkgs       freezeFlags)

cabal-install/Distribution/Client/Install.hs

@@ -395,6 +395,8 @@ planPackages verbosity comp platform mSandboxPkgInfo solver
 
       . setCountConflicts countConflicts
 
+      . setFineGrainedConflicts fineGrainedConflicts
+
       . setMinimizeConflictSet minimizeConflictSet
 
       . setAvoidReinstalls avoidReinstalls
@@ -463,6 +465,7 @@ planPackages verbosity comp platform mSandboxPkgInfo solver
                        fromFlag (installReinstall         installFlags)
     reorderGoals     = fromFlag (installReorderGoals      installFlags)
     countConflicts   = fromFlag (installCountConflicts    installFlags)
+    fineGrainedConflicts = fromFlag (installFineGrainedConflicts installFlags)
     minimizeConflictSet = fromFlag (installMinimizeConflictSet installFlags)
     independentGoals = fromFlag (installIndependentGoals  installFlags)
     avoidReinstalls  = fromFlag (installAvoidReinstalls   installFlags)

cabal-install/Distribution/Client/ProjectConfig.hs

@@ -250,6 +250,7 @@ resolveSolverSettings ProjectConfig{
                                          | otherwise -> Just n
     solverSettingReorderGoals      = fromFlag projectConfigReorderGoals
     solverSettingCountConflicts    = fromFlag projectConfigCountConflicts
+    solverSettingFineGrainedConflicts = fromFlag projectConfigFineGrainedConflicts
     solverSettingMinimizeConflictSet = fromFlag projectConfigMinimizeConflictSet
     solverSettingStrongFlags       = fromFlag projectConfigStrongFlags
     solverSettingAllowBootLibInstalls = fromFlag projectConfigAllowBootLibInstalls
@@ -271,6 +272,7 @@ resolveSolverSettings ProjectConfig{
        projectConfigMaxBackjumps      = Flag defaultMaxBackjumps,
        projectConfigReorderGoals      = Flag (ReorderGoals False),
        projectConfigCountConflicts    = Flag (CountConflicts True),
+       projectConfigFineGrainedConflicts = Flag (FineGrainedConflicts True),
        projectConfigMinimizeConflictSet = Flag (MinimizeConflictSet False),
        projectConfigStrongFlags       = Flag (StrongFlags False),
        projectConfigAllowBootLibInstalls = Flag (AllowBootLibInstalls False),

cabal-install/Distribution/Client/ProjectConfig/Legacy.hs

@@ -374,6 +374,7 @@ convertLegacyAllPackageFlags globalFlags configFlags
     --installUpgradeDeps        = projectConfigUpgradeDeps,
       installReorderGoals       = projectConfigReorderGoals,
       installCountConflicts     = projectConfigCountConflicts,
+      installFineGrainedConflicts = projectConfigFineGrainedConflicts,
       installMinimizeConflictSet = projectConfigMinimizeConflictSet,
       installPerComponent       = projectConfigPerComponent,
       installIndependentGoals   = projectConfigIndependentGoals,
@@ -611,6 +612,7 @@ convertToLegacySharedConfig
       installUpgradeDeps       = mempty, --projectConfigUpgradeDeps,
       installReorderGoals      = projectConfigReorderGoals,
       installCountConflicts    = projectConfigCountConflicts,
+      installFineGrainedConflicts = projectConfigFineGrainedConflicts,
       installMinimizeConflictSet = projectConfigMinimizeConflictSet,
       installIndependentGoals  = projectConfigIndependentGoals,
       installShadowPkgs        = mempty, --projectConfigShadowPkgs,
@@ -1004,8 +1006,9 @@ legacySharedConfigFieldDescrs =
       , "one-shot", "jobs", "keep-going", "offline", "per-component"
         -- solver flags:
       , "max-backjumps", "reorder-goals", "count-conflicts"
-      , "minimize-conflict-set", "independent-goals"
-      , "strong-flags" , "allow-boot-library-installs", "reject-unconstrained-dependencies", "index-state"
+      , "fine-grained-conflicts" , "minimize-conflict-set", "independent-goals"
+      , "strong-flags" , "allow-boot-library-installs"
+      , "reject-unconstrained-dependencies", "index-state"
       ]
   . commandOptionsToFields
   ) (installOptions ParseArgs)

cabal-install/Distribution/Client/ProjectConfig/Types.hs

@@ -195,6 +195,7 @@ data ProjectConfigShared
        projectConfigMaxBackjumps      :: Flag Int,
        projectConfigReorderGoals      :: Flag ReorderGoals,
        projectConfigCountConflicts    :: Flag CountConflicts,
+       projectConfigFineGrainedConflicts :: Flag FineGrainedConflicts,
        projectConfigMinimizeConflictSet :: Flag MinimizeConflictSet,
        projectConfigStrongFlags       :: Flag StrongFlags,
        projectConfigAllowBootLibInstalls :: Flag AllowBootLibInstalls,
@@ -400,6 +401,7 @@ data SolverSettings
        solverSettingMaxBackjumps      :: Maybe Int,
        solverSettingReorderGoals      :: ReorderGoals,
        solverSettingCountConflicts    :: CountConflicts,
+       solverSettingFineGrainedConflicts :: FineGrainedConflicts,
        solverSettingMinimizeConflictSet :: MinimizeConflictSet,
        solverSettingStrongFlags       :: StrongFlags,
        solverSettingAllowBootLibInstalls :: AllowBootLibInstalls,

cabal-install/Distribution/Client/ProjectPlanning.hs

@@ -958,6 +958,8 @@ planPackages verbosity comp platform solver SolverSettings{..}
 
       . setCountConflicts solverSettingCountConflicts
 
+      . setFineGrainedConflicts solverSettingFineGrainedConflicts
+
       . setMinimizeConflictSet solverSettingMinimizeConflictSet
 
         --TODO: [required eventually] should only be configurable for

cabal-install/Distribution/Client/Setup.hs

@@ -1003,6 +1003,7 @@ data FetchFlags = FetchFlags {
       fetchMaxBackjumps     :: Flag Int,
       fetchReorderGoals     :: Flag ReorderGoals,
       fetchCountConflicts   :: Flag CountConflicts,
+      fetchFineGrainedConflicts :: Flag FineGrainedConflicts,
       fetchMinimizeConflictSet :: Flag MinimizeConflictSet,
       fetchIndependentGoals :: Flag IndependentGoals,
       fetchShadowPkgs       :: Flag ShadowPkgs,
@@ -1023,6 +1024,7 @@ defaultFetchFlags = FetchFlags {
     fetchMaxBackjumps     = Flag defaultMaxBackjumps,
     fetchReorderGoals     = Flag (ReorderGoals False),
     fetchCountConflicts   = Flag (CountConflicts True),
+    fetchFineGrainedConflicts = Flag (FineGrainedConflicts True),
     fetchMinimizeConflictSet = Flag (MinimizeConflictSet False),
     fetchIndependentGoals = Flag (IndependentGoals False),
     fetchShadowPkgs       = Flag (ShadowPkgs False),
@@ -1085,6 +1087,7 @@ fetchCommand = CommandUI {
                          fetchMaxBackjumps     (\v flags -> flags { fetchMaxBackjumps     = v })
                          fetchReorderGoals     (\v flags -> flags { fetchReorderGoals     = v })
                          fetchCountConflicts   (\v flags -> flags { fetchCountConflicts   = v })
+                         fetchFineGrainedConflicts (\v flags -> flags { fetchFineGrainedConflicts = v })
                          fetchMinimizeConflictSet (\v flags -> flags { fetchMinimizeConflictSet = v })
                          fetchIndependentGoals (\v flags -> flags { fetchIndependentGoals = v })
                          fetchShadowPkgs       (\v flags -> flags { fetchShadowPkgs       = v })
@@ -1106,6 +1109,7 @@ data FreezeFlags = FreezeFlags {
       freezeMaxBackjumps     :: Flag Int,
       freezeReorderGoals     :: Flag ReorderGoals,
       freezeCountConflicts   :: Flag CountConflicts,
+      freezeFineGrainedConflicts :: Flag FineGrainedConflicts,
       freezeMinimizeConflictSet :: Flag MinimizeConflictSet,
       freezeIndependentGoals :: Flag IndependentGoals,
       freezeShadowPkgs       :: Flag ShadowPkgs,
@@ -1124,6 +1128,7 @@ defaultFreezeFlags = FreezeFlags {
     freezeMaxBackjumps     = Flag defaultMaxBackjumps,
     freezeReorderGoals     = Flag (ReorderGoals False),
     freezeCountConflicts   = Flag (CountConflicts True),
+    freezeFineGrainedConflicts = Flag (FineGrainedConflicts True),
     freezeMinimizeConflictSet = Flag (MinimizeConflictSet False),
     freezeIndependentGoals = Flag (IndependentGoals False),
     freezeShadowPkgs       = Flag (ShadowPkgs False),
@@ -1177,6 +1182,7 @@ freezeCommand = CommandUI {
                          freezeMaxBackjumps     (\v flags -> flags { freezeMaxBackjumps     = v })
                          freezeReorderGoals     (\v flags -> flags { freezeReorderGoals     = v })
                          freezeCountConflicts   (\v flags -> flags { freezeCountConflicts   = v })
+                         freezeFineGrainedConflicts (\v flags -> flags { freezeFineGrainedConflicts = v })
                          freezeMinimizeConflictSet (\v flags -> flags { freezeMinimizeConflictSet = v })
                          freezeIndependentGoals (\v flags -> flags { freezeIndependentGoals = v })
                          freezeShadowPkgs       (\v flags -> flags { freezeShadowPkgs       = v })
@@ -1749,6 +1755,7 @@ data InstallFlags = InstallFlags {
     installMaxBackjumps     :: Flag Int,
     installReorderGoals     :: Flag ReorderGoals,
     installCountConflicts   :: Flag CountConflicts,
+    installFineGrainedConflicts :: Flag FineGrainedConflicts,
     installMinimizeConflictSet :: Flag MinimizeConflictSet,
     installIndependentGoals :: Flag IndependentGoals,
     installShadowPkgs       :: Flag ShadowPkgs,
@@ -1798,6 +1805,7 @@ defaultInstallFlags = InstallFlags {
     installMaxBackjumps    = Flag defaultMaxBackjumps,
     installReorderGoals    = Flag (ReorderGoals False),
     installCountConflicts  = Flag (CountConflicts True),
+    installFineGrainedConflicts = Flag (FineGrainedConflicts True),
     installMinimizeConflictSet = Flag (MinimizeConflictSet False),
     installIndependentGoals= Flag (IndependentGoals False),
     installShadowPkgs      = Flag (ShadowPkgs False),
@@ -2028,6 +2036,7 @@ installOptions showOrParseArgs =
                         installMaxBackjumps     (\v flags -> flags { installMaxBackjumps     = v })
                         installReorderGoals     (\v flags -> flags { installReorderGoals     = v })
                         installCountConflicts   (\v flags -> flags { installCountConflicts   = v })
+                        installFineGrainedConflicts (\v flags -> flags { installFineGrainedConflicts = v })
                         installMinimizeConflictSet (\v flags -> flags { installMinimizeConflictSet = v })
                         installIndependentGoals (\v flags -> flags { installIndependentGoals = v })
                         installShadowPkgs       (\v flags -> flags { installShadowPkgs       = v })
@@ -2860,6 +2869,7 @@ optionSolverFlags :: ShowOrParseArgs
                   -> (flags -> Flag Int   ) -> (Flag Int    -> flags -> flags)
                   -> (flags -> Flag ReorderGoals)     -> (Flag ReorderGoals     -> flags -> flags)
                   -> (flags -> Flag CountConflicts)   -> (Flag CountConflicts   -> flags -> flags)
+                  -> (flags -> Flag FineGrainedConflicts) -> (Flag FineGrainedConflicts -> flags -> flags)
                   -> (flags -> Flag MinimizeConflictSet) -> (Flag MinimizeConflictSet -> flags -> flags)
                   -> (flags -> Flag IndependentGoals) -> (Flag IndependentGoals -> flags -> flags)
                   -> (flags -> Flag ShadowPkgs)       -> (Flag ShadowPkgs       -> flags -> flags)
@@ -2868,8 +2878,8 @@ optionSolverFlags :: ShowOrParseArgs
                   -> (flags -> Flag OnlyConstrained)  -> (Flag OnlyConstrained  -> flags -> flags)
                   -> [OptionField flags]
 optionSolverFlags showOrParseArgs getmbj setmbj getrg setrg getcc setcc
-                  getmc setmc getig setig getsip setsip getstrfl setstrfl
-                  getib setib getoc setoc =
+                  getfgc setfgc getmc setmc getig setig getsip setsip
+                  getstrfl setstrfl getib setib getoc setoc =
   [ option [] ["max-backjumps"]
       ("Maximum number of backjumps allowed while solving (default: " ++ show defaultMaxBackjumps ++ "). Use a negative number to enable unlimited backtracking. Use 0 to disable backtracking completely.")
       getmbj setmbj
@@ -2885,6 +2895,11 @@ optionSolverFlags showOrParseArgs getmbj setmbj getrg setrg getcc setcc
       (fmap asBool . getcc)
       (setcc . fmap CountConflicts)
       (yesNoOpt showOrParseArgs)
+  , option [] ["fine-grained-conflicts"]
+      "Skip a version of a package if it does not resolve the conflicts encountered in the last version, as a solver optimization (default)."
+      (fmap asBool . getfgc)
+      (setfgc . fmap FineGrainedConflicts)
+      (yesNoOpt showOrParseArgs)
   , option [] ["minimize-conflict-set"]
       ("When there is no solution, try to improve the error message by finding "
         ++ "a minimal conflict set (default: false). May increase run time "

cabal-install/Distribution/Solver/Modular/Builder.hs

@@ -145,7 +145,9 @@ addChildren bs@(BS { rdeps = rdm, open = gs, next = Goals })
 -- and then handle each instance in turn.
 addChildren bs@(BS { rdeps = rdm, index = idx, next = OneGoal (PkgGoal qpn@(Q _ pn) gr) }) =
   case M.lookup pn idx of
-    Nothing  -> FailF (varToConflictSet (P qpn) `CS.union` goalReasonToConflictSet gr) UnknownPackage
+    Nothing  -> FailF
+                (varToConflictSet (P qpn) `CS.union` goalReasonToConflictSetWithConflict qpn gr)
+                UnknownPackage
     Just pis -> PChoiceF qpn rdm gr (W.fromList (L.map (\ (i, info) ->
                                                        ([], POption i Nothing, bs { next = Instance qpn info }))
                                                      (M.toList pis)))