From fc5db2cd4fc3030fdc4cad0e6e38e7f80a7aa71b Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Sat, 4 Feb 2023 15:07:41 -0800 Subject: [PATCH] Implement -Zlink-directives=yes/no `-Zlink-directives=no` will ignored `#[link]` directives while compiling a crate, so nothing is emitted into the crate's metadata. The assumption is that the build system already knows about the crate's native dependencies and can provide them at link time without these directives. This is another way to address issue # #70093, which is currently addressed by `-Zlink-native-libraries` (implemented in #70095). The latter is implemented at link time, which has the effect of ignoring `#[link]` in *every* crate. This makes it a very large hammer as it requires all native dependencies to be known to the build system to be at all usable, including those in sysroot libraries. I think this means its effectively unused, and definitely under-used. Being able to control this on a crate-by-crate basis should make it much easier to apply when needed. I'm not sure if we need both mechanisms, but we can decide that later. --- compiler/rustc_interface/src/tests.rs | 1 + compiler/rustc_metadata/src/native_libs.rs | 7 ++++++- compiler/rustc_session/src/options.rs | 2 ++ tests/rustdoc-ui/z-help.stdout | 1 + .../issues/issue-70093/issue-70093-link-directives.rs | 10 ++++++++++ tests/ui/issues/{ => issue-70093}/issue-70093.rs | 0 6 files changed, 20 insertions(+), 1 deletion(-) create mode 100644 tests/ui/issues/issue-70093/issue-70093-link-directives.rs rename tests/ui/issues/{ => issue-70093}/issue-70093.rs (100%) diff --git a/compiler/rustc_interface/src/tests.rs b/compiler/rustc_interface/src/tests.rs index bfb1e822a2697..f9f4c0ec70854 100644 --- a/compiler/rustc_interface/src/tests.rs +++ b/compiler/rustc_interface/src/tests.rs @@ -756,6 +756,7 @@ fn test_unstable_options_tracking_hash() { tracked!(instrument_coverage, Some(InstrumentCoverage::All)); tracked!(instrument_mcount, true); tracked!(instrument_xray, Some(InstrumentXRay::default())); + tracked!(link_directives, false); tracked!(link_only, true); tracked!(llvm_plugins, vec![String::from("plugin_name")]); tracked!(location_detail, LocationDetail { file: true, line: false, column: false }); diff --git a/compiler/rustc_metadata/src/native_libs.rs b/compiler/rustc_metadata/src/native_libs.rs index d823989bb02b8..91cb35f672448 100644 --- a/compiler/rustc_metadata/src/native_libs.rs +++ b/compiler/rustc_metadata/src/native_libs.rs @@ -103,8 +103,13 @@ impl<'tcx> Collector<'tcx> { } // Process all of the #[link(..)]-style arguments - let sess = &self.tcx.sess; + let sess = self.tcx.sess; let features = self.tcx.features(); + + if !sess.opts.unstable_opts.link_directives { + return; + } + for m in self.tcx.hir().attrs(it.hir_id()).iter().filter(|a| a.has_name(sym::link)) { let Some(items) = m.meta_item_list() else { continue; diff --git a/compiler/rustc_session/src/options.rs b/compiler/rustc_session/src/options.rs index 1f3eb8d4832fe..eb8e54fa0bd27 100644 --- a/compiler/rustc_session/src/options.rs +++ b/compiler/rustc_session/src/options.rs @@ -1489,6 +1489,8 @@ options! { "keep hygiene data after analysis (default: no)"), layout_seed: Option = (None, parse_opt_number, [TRACKED], "seed layout randomization"), + link_directives: bool = (true, parse_bool, [TRACKED], + "honour #[link] directives in crates (default: yes)"), link_native_libraries: bool = (true, parse_bool, [UNTRACKED], "link native libraries in the linker invocation (default: yes)"), link_only: bool = (false, parse_bool, [TRACKED], diff --git a/tests/rustdoc-ui/z-help.stdout b/tests/rustdoc-ui/z-help.stdout index 58b2f92d15040..55876326e5eab 100644 --- a/tests/rustdoc-ui/z-help.stdout +++ b/tests/rustdoc-ui/z-help.stdout @@ -81,6 +81,7 @@ Multiple options can be combined with commas. -Z keep-hygiene-data=val -- keep hygiene data after analysis (default: no) -Z layout-seed=val -- seed layout randomization + -Z link-directives=val -- honour #[link] directives in crates (default: yes) -Z link-native-libraries=val -- link native libraries in the linker invocation (default: yes) -Z link-only=val -- link the `.rlink` file generated by `-Z no-link` (default: no) -Z llvm-plugins=val -- a list LLVM plugins to enable (space separated) diff --git a/tests/ui/issues/issue-70093/issue-70093-link-directives.rs b/tests/ui/issues/issue-70093/issue-70093-link-directives.rs new file mode 100644 index 0000000000000..83f9b16c4086a --- /dev/null +++ b/tests/ui/issues/issue-70093/issue-70093-link-directives.rs @@ -0,0 +1,10 @@ +// run-pass +// compile-flags: -Zlink-directives=no +// ignore-windows - this will probably only work on unixish systems +// ignore-fuchsia - missing __libc_start_main for some reason (#84733) +// ignore-cross-compile - default-linker-libraries=yes doesn't play well with cross compiling + +#[link(name = "some-random-non-existent-library", kind = "static")] +extern "C" {} + +fn main() {} diff --git a/tests/ui/issues/issue-70093.rs b/tests/ui/issues/issue-70093/issue-70093.rs similarity index 100% rename from tests/ui/issues/issue-70093.rs rename to tests/ui/issues/issue-70093/issue-70093.rs