Proper boolean options; enable-matcher; imply enable-stack

The options `enable-stack`, `stack-no-global`, `stack-setup-ghc` and `disable-matcher` are now proper booleans only accepting `true` or `false`.
Previously, they were true when set to some non-empty string, even when set to "false" or "off" etc.

`disable-matcher` is deprecated in favour of a new positive form `enable-matcher`.

`enable-stack` is now implied by setting another stack-related option, i.e., one of `stack-version`, `stack-no-global` and `stack-setup-ghc`.
Previously, it was a prerequisite to these options.

Contradictory options now give an error, such as `stack-no-global` with `ghc-version` or `enable-stack: false` with `stack-version`.

Fixes: haskell/actions#142

README.md

@@ -190,23 +190,18 @@ jobs:
 
 ## Inputs
 
-| Name                    | Description                                                                                                                                 | Type      | Default     |
-| ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | --------- | ----------- |
-| `ghc-version`           | GHC version to use, e.g. `9.2` or `9.2.5`.                                                                                                  | `string`  | `latest`    |
-| `cabal-version`         | Cabal version to use, e.g. `3.6`.                                                                                                           | `string`  | `latest`    |
-| `stack-version`         | Stack version to use, e.g. `latest`. Stack will only be installed if `enable-stack` is set.                                                 | `string`  | `latest`    |
-| `enable-stack`          | If set, will setup Stack.                                                                                                                   | "boolean" | false/unset |
-| `stack-no-global`       | If set, `enable-stack` must be set. Prevents installing GHC and Cabal globally.                                                             | "boolean" | false/unset |
-| `stack-setup-ghc`       | If set, `enable-stack` must be set. Runs stack setup to install the specified GHC. (Note: setting this does _not_ imply `stack-no-global`.) | "boolean" | false/unset |
-| `disable-matcher`       | If set, disables match messages from GHC as GitHub CI annotations.                                                                          | "boolean" | false/unset |
-| `cabal-update`          | If set to `false`, skip `cabal update` step.                                                                                                | `boolean` | `true`      |
-| `ghcup-release-channel` | If set, add a [release channel](https://www.haskell.org/ghcup/guide/#pre-release-channels) to ghcup.                                        | `URL`     | none        |
-
-Note: "boolean" types are set/unset, not true/false.
-That is, setting any "boolean" to a value other than the empty string (`""`) will be considered true/set.
-However, to avoid confusion and for forward compatibility, it is still recommended to **only use value `true` to set a "boolean" flag.**
-
-In contrast, a proper `boolean` input like `cabal-update` only accepts values `true` and `false`.
+| Name                    | Description                                                                                                                     | Type      | Default  |
+| ----------------------- | ------------------------------------------------------------------------------------------------------------------------------- | --------- | -------- |
+| `ghc-version`           | GHC version to use, e.g. `9.2` or `9.2.5`.                                                                                      | `string`  | `latest` |
+| `cabal-version`         | Cabal version to use, e.g. `3.6`.                                                                                               | `string`  | `latest` |
+| `stack-version`         | Stack version to use, e.g. `latest`. Implies `enable-stack`.                                                                    | `string`  | `latest` |
+| `enable-stack`          | Setup Stack. Implied by `stack-version`, `stack-no-global`, `stack-setup-ghc`.                                                  | `boolean` | `false`  |
+| `stack-no-global`       | Implies `enable-stack`. Prevents installing GHC and Cabal globally.                                                             | `boolean` | `false`  |
+| `stack-setup-ghc`       | Implies `enable-stack`. Runs stack setup to install the specified GHC. (Note: setting this does _not_ imply `stack-no-global`.) | `boolean` | `false`  |
+| `enable-matcher`        | Enable match messages from GHC as GitHub CI annotations.                                                                        | `boolean` | `true`   |
+| `disable-matcher`       | Disable match messages from GHC as GitHub CI annotations. (Legacy option, deprecated in favour of `enable-matcher`.)            | `boolean` | `false`  |
+| `cabal-update`          | Perform `cabal update` step. (Default if Cabal is enabled.)                                                                     | `boolean` | `true`   |
+| `ghcup-release-channel` | If set, add a [release channel](https://www.haskell.org/ghcup/guide/#pre-release-channels) to ghcup.                            | `URL`     | none     |
 
 ## Outputs
 

__tests__/find-haskell.test.ts

@@ -43,6 +43,14 @@ describe('haskell-actions/setup', () => {
       forAllTools(t => expect(def(os)[t].supported).toBe(supported_versions[t]))
     ));
 
+  it('Setting enable-matcher to false disables matcher', () => {
+    forAllOS(os => {
+      const options = getOpts(def(os), os, {
+        'enable-matcher': 'false'
+      });
+      expect(options.general.matcher.enable).toBe(false);
+    });
+  });
   it('Setting disable-matcher to true disables matcher', () => {
     forAllOS(os => {
       const options = getOpts(def(os), os, {
@@ -51,6 +59,25 @@ describe('haskell-actions/setup', () => {
       expect(options.general.matcher.enable).toBe(false);
     });
   });
+  it('Setting both enable-matcher to false and disable-matcher to true disables matcher', () => {
+    forAllOS(os => {
+      const options = getOpts(def(os), os, {
+        'enable-matcher': 'false',
+        'disable-matcher': 'true'
+      });
+      expect(options.general.matcher.enable).toBe(false);
+    });
+  });
+  it('Setting both enable-matcher and disable-matcher to true errors', () => {
+    forAllOS(os =>
+      expect(() =>
+        getOpts(def(os), os, {
+          'enable-matcher': 'true',
+          'disable-matcher': 'true'
+        })
+      ).toThrow()
+    );
+  });
 
   it('getOpts grabs default general settings correctly from environment', () => {
     forAllOS(os => {
@@ -148,15 +175,35 @@ describe('haskell-actions/setup', () => {
     });
   });
 
-  it('Enabling stack-no-global without setting enable-stack errors', () => {
+  it('Enabling stack-no-global but disabling enable-stack errors', () => {
     forAllOS(os =>
-      expect(() => getOpts(def(os), os, {'stack-no-global': 'true'})).toThrow()
+      expect(() =>
+        getOpts(def(os), os, {
+          'stack-no-global': 'true',
+          'enable-stack': 'false'
+        })
+      ).toThrow()
     );
   });
 
-  it('Enabling stack-setup-ghc without setting enable-stack errors', () => {
+  it('Enabling stack-no-global but setting ghc-version errors', () => {
+    forAllOS(os =>
+      expect(() =>
+        getOpts(def(os), os, {
+          'stack-no-global': 'true',
+          'ghc-version': 'latest'
+        })
+      ).toThrow()
+    );
+  });
+  it('Enabling stack-no-global but setting cabal-version errors', () => {
     forAllOS(os =>
-      expect(() => getOpts(def(os), os, {'stack-setup-ghc': 'true'})).toThrow()
+      expect(() =>
+        getOpts(def(os), os, {
+          'stack-no-global': 'true',
+          'cabal-version': 'latest'
+        })
+      ).toThrow()
     );
   });
 });

action.yml

@@ -1,6 +1,6 @@
 name: 'Setup Haskell'
 description: 'Set up a specific version of GHC and Cabal and add the command-line tools to the PATH'
-author: 'GitHub'
+author: 'Haskell community'
 inputs:
   ghc-version:
     required: false
@@ -16,13 +16,16 @@ inputs:
     default: 'latest'
   enable-stack:
     required: false
-    description: 'If specified, will setup Stack.'
+    default: false
+    description: 'If set to `true`, will setup default Stack.  Implied by any of `stack-version`, `stack-no-global`, `stack-setup-ghc`.'
   stack-no-global:
     required: false
-    description: 'If specified, enable-stack must be set. Prevents installing GHC and Cabal globally.'
+    default: false
+    description: 'If set to `true`, will setup Stack but will not install GHC and Cabal globally.'
   stack-setup-ghc:
     required: false
-    description: 'If specified, enable-stack must be set. Will run stack setup to install the specified GHC.'
+    default: false
+    description: 'If set to `true`, will setup Stack. Will run `stack setup` to install the specified GHC.'
   cabal-update:
     required: false
     default: true
@@ -33,9 +36,14 @@ inputs:
   ghcup-release-channel:
     required: false
     description: "A release channel URL to add to ghcup via `ghcup config add-release-channel`."
+  enable-matcher:
+    required: false
+    default: true
+    description: 'Enable match messages from GHC as GitHub CI annotations.'
   disable-matcher:
     required: false
-    description: 'If specified, disables match messages from GHC as GitHub CI annotations.'
+    default: false
+    description: 'Legacy input, use `enable-matcher` instead.'
 outputs:
   ghc-version:
     description: 'The resolved version of ghc'