Merge pull request #210762 from sternenseemann/nix-ghc-docdir

ghc.withPackages: install documentation to -with-packages output

nixos/doc/manual/from_md/release-notes/rl-2305.section.xml

@@ -371,6 +371,17 @@
           <literal>nixos/modules/profiles/minimal.nix</literal> profile.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          The <literal>ghcWithPackages</literal> and
+          <literal>ghcWithHoogle</literal> wrappers will now also
+          symlink GHC’s and all included libraries’ documentation to
+          <literal>$out/share/doc</literal> for convenience. If
+          undesired, the old behavior can be restored by overriding the
+          builders with
+          <literal>{ installDocumentation = false; }</literal>.
+        </para>
+      </listitem>
       <listitem>
         <para>
           <literal>mastodon</literal> now supports connection to a

nixos/doc/manual/release-notes/rl-2305.section.md

@@ -100,6 +100,11 @@ In addition to numerous new and upgraded packages, this release has the followin
 
 - The minimal ISO image now uses the `nixos/modules/profiles/minimal.nix` profile.
 
+- The `ghcWithPackages` and `ghcWithHoogle` wrappers will now also symlink GHC's
+  and all included libraries' documentation to `$out/share/doc` for convenience.
+  If undesired, the old behavior can be restored by overriding the builders with
+  `{ installDocumentation = false; }`.
+
 - `mastodon` now supports connection to a remote `PostgreSQL` database.
 
 - `services.peertube` now requires you to specify the secret file `secrets.secretsFile`. It can be generated by running `openssl rand -hex 32`.

pkgs/development/haskell-modules/with-packages-wrapper.nix

@@ -4,6 +4,8 @@
 # platform that has NCG support
 , useLLVM ? false
 , withHoogle ? false
+# Whether to install `doc` outputs for GHC and all included libraries.
+, installDocumentation ? true
 , hoogleWithPackages
 , postBuild ? ""
 , ghcLibdir ? null # only used by ghcjs, when resolving plugins
@@ -54,7 +56,11 @@ let
                   else "$out/lib/${ghc.targetPrefix}${ghc.haskellCompilerName}";
   docDir        = "$out/share/doc/ghc/html";
   packageCfgDir = "${libDir}/package.conf.d";
-  paths         = lib.filter (x: x ? isHaskellLibrary) (lib.closePropagation packages);
+  paths         = lib.concatLists (
+                    builtins.map
+                      (pkg: [ pkg ] ++ lib.optionals installDocumentation [ (lib.getOutput "doc" pkg) ])
+                      (lib.filter (x: x ? isHaskellLibrary) (lib.closePropagation packages))
+                  );
   hasLibraries  = lib.any (x: x.isHaskellLibrary) paths;
   # CLang is needed on Darwin for -fllvm to work:
   # https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/codegens.html#llvm-code-generator-fllvm
@@ -71,7 +77,9 @@ symlinkJoin {
   # if such a feature is needed, the real compiler name should be saved
   # as a dedicated drv attribute, like `compiler-name`
   name = ghc.name + "-with-packages";
-  paths = paths ++ [ghc];
+  paths = paths
+          ++ [ ghc ]
+          ++ lib.optionals installDocumentation [ ghc.doc ];
   nativeBuildInputs = [ makeWrapper ];
   postBuild = ''
     # wrap compiler executables with correct env variables