Merge branch 'hkm/use-cabal-3.8' into hkm/combined-derivations

# Conflicts:
#	lib/call-cabal-project-to-nix.nix
#	overlays/default.nix

Author: hamishmack

builder/comp-builder.nix

@@ -239,7 +239,7 @@ let
     (lib.concatMap (c: if c.isHaskell or false
       then builtins.attrValues (c.components.exes or {})
       else [c]) build-tools) ++
-    lib.optional (pkgconfig != []) buildPackages.pkgconfig;
+    lib.optional (pkgconfig != []) buildPackages.cabalPkgConfigWrapper;
 
   # Unfortunately, we need to wrap ghc commands for cabal builds to
   # work in the nix-shell. See ../doc/removing-with-package-wrapper.md.

builder/default.nix

@@ -17,7 +17,7 @@ let
     # in the native case, it would be the same in the cross case however
     # we *really* want to build the Setup.hs on the build machine and not
     # have the stdenv confuse it with the target/host env.
-    inherit (buildPackages) stdenv pkgconfig;
+    inherit (buildPackages) stdenv;
     inherit buildPackages;
     inherit haskellLib nonReinstallablePkgs makeSetupConfigFiles;
   };

builder/setup-builder.nix

@@ -1,4 +1,4 @@
-{ pkgs, stdenv, lib, buildPackages, haskellLib, ghc, nonReinstallablePkgs, hsPkgs, makeSetupConfigFiles, pkgconfig }@defaults:
+{ pkgs, stdenv, lib, buildPackages, haskellLib, ghc, nonReinstallablePkgs, hsPkgs, makeSetupConfigFiles }@defaults:
 
 let self =
 { component, package, name, src, enableDWARF ? false, flags ? {}, revision ? null, patches ? [], defaultSetupSrc
@@ -36,7 +36,7 @@ let
     (lib.concatMap (c: if c.isHaskell or false
       then builtins.attrValues (c.components.exes or {})
       else [c]) component.build-tools) ++
-    lib.optional (component.pkgconfig != []) pkgconfig;
+    lib.optional (component.pkgconfig != []) buildPackages.cabalPkgConfigWrapper;
 
   drv =
     stdenv.mkDerivation ({

changelog.md

@@ -1,6 +1,36 @@
 This file contains a summary of changes to Haskell.nix and `nix-tools`
 that will impact users.
 
+## Sep 6, 2022
+* A `pkgconfigSelector` must now be passed to cabal projects that have
+  `pkgconfig-depends`.  Use the pkg-config names.  For instance if the
+  project uses `gi-gtk` pass:
+  ```
+  pkgconfigSelector = p: [ p."gtk+-3.0" p."gobject-introspection-1.0" ];
+  ```
+  The dependencies of gtk will be included automatically.
+
+  Why?
+
+  Cabal 3.8 fixes a bug https://github.com/haskell/cabal/issues/6771
+  that haskell.nix relied on (probably wrongly), to create a plan
+  for a haskell project without knowing the pkg-config versions
+  available ahead of time.
+
+  This was probably a bad idea.
+
+  We could try to provide every pkg-config derivation in nixpkgs to
+  the derivation that generates the cabal plan. Unfortunately:
+  * That would introduce a massive dependency tree to the plan-nix
+    dervaition.
+  * Some of those packages may not build.
+
+  The `pkgconfigSelector` allows haskell.nix to filter out only the
+  packages we need from the available map (`lib/pkgconf-nixpkgs-map.nix`).
+
+  It should be thought of as the haskell.nix equivalent of installing
+  your pkg-config dependencies before running `cabal build`.
+
 ## Jul 27, 2022
 * Removed reliance on `builtins.currentSystem`.  It was used it to provide
   `pkgs.evalPackages` via an overlay that it used to run derivations

lib/call-cabal-project-to-nix.nix

@@ -66,7 +66,7 @@ in
                             # any plutus-apps input being used for a
                             # package.
 , evalPackages
-, pkgconfSelector ? (_: [])
+, pkgconfigSelector ? (_: [])
 , supportHpack ? false      # Run hpack on package.yaml files with no .cabal file
 , ...
 }@args:
@@ -471,7 +471,9 @@ let
       nix-tools.exes.plan-to-nix
       dummy-ghc dummy-ghc-pkg cabal-install evalPackages.rsync evalPackages.gitMinimal evalPackages.pkgconfig ]
       ++ pkgs.lib.optional supportHpack nix-tools.exes.hpack;
-    buildInputs = pkgconfSelector pkgconfPkgs;
+    # We only need the `.dev` derivation (if there is one), since it will have
+    # the pkgconfig files needed by cabal.
+    buildInputs = map pkgs.lib.getDev (builtins.concatLists (pkgconfigSelector pkgconfPkgs));
     # Needed or stack-to-nix will die on unicode inputs
     LOCALE_ARCHIVE = pkgs.lib.optionalString (evalPackages.stdenv.buildPlatform.libc == "glibc") "${evalPackages.glibcLocales}/lib/locale/locale-archive";
     LANG = "en_US.UTF-8";

lib/pkgconf-nixpkgs-map.nix

@@ -143,8 +143,7 @@ pkgs:
     "sctp"                               = [ pkgs."lksctp-tools" ]; # This is linux-specific, we should create a common attribute if we ever add sctp support for other systems.
     "sdl2"                               = [ pkgs."SDL2" ];
     "sndfile"                            = [ pkgs."libsndfile" ];
-    "sodium"                             = [ pkgs."libsodium".dev ];
-    "libsodium"                          = [ pkgs."libsodium".dev ];
+    "sodium"                             = [ pkgs."libsodium" ];
     "sqlite3"                            = [ pkgs."sqlite" ];
     "ssh2"                               = [ pkgs."libssh2" ];
     "statgrab"                           = [ pkgs."libstatgrab" ];

modules/cabal-project.nix

@@ -134,9 +134,18 @@ in {
       type = nullOr (listOf unspecified);
       default = [];
     };
-    pkgconfSelector = mkOption {
+    pkgconfigSelector = mkOption {
       type = unspecified;
       default = (_: []);
+      description = ''
+        Choose the pkg-config packages that should be made available to
+        cabal configure.  Use the pkg-config names.  For instance if the
+        project uses `gi-gtk` pass:
+        ```
+        pkgconfigSelector = p: [ p."gtk+-3.0" p."gobject-introspection-1.0" ];
+        ```
+        The dependencies of gtk will be included automatically.
+      '';
     };
   };
 }

overlays/cabal-pkg-config.nix

@@ -0,0 +1,38 @@
+final: prev:
+{
+  # cabal 3.8 asks pkg-config for linker options for both
+  # dynamic and static linking.
+  # For some derivations (glib for instance) pkg-config can
+  # fail when `--static` is passed.  This might be because
+  # the library only has dynamic libraries. 
+  #
+  # To work around this problem this wrapper makes cabal lazy
+  # by return a single command line option when it fails.
+  # That option should never be used and if it is hopefully
+  # the name of the option itself will be helpful.
+  #
+  # See https://github.com/input-output-hk/haskell.nix/issues/1642
+  #
+  cabalPkgConfigWrapper = prev.pkgconfig.overrideAttrs (attrs: {
+    installPhase = attrs.installPhase + ''
+      mv $out/bin/${attrs.targetPrefix}${attrs.baseBinName} \
+        $out/bin/${attrs.targetPrefix}${attrs.baseBinName}-wrapped
+
+      cat <<EOF >$out/bin/${attrs.targetPrefix}${attrs.baseBinName}      
+      #!${final.stdenv.shell}
+      if [[ "\$1" == "--libs" && "\$2" == "--static" ]]; then
+        OUTPUT=\$(mktemp)
+        ERROR=\$(mktemp)
+        if $out/bin/${attrs.targetPrefix}${attrs.baseBinName}-wrapped "\$@" >output 2>\$ERROR; then
+          cat \$OUTPUT
+        else
+          echo "--error-pkg-config-static-failed=\$ERROR"
+        fi
+      else
+        $out/bin/${attrs.targetPrefix}${attrs.baseBinName}-wrapped "\$@"
+      fi
+      EOF
+      chmod +x $out/bin/${attrs.targetPrefix}${attrs.baseBinName}
+    '';
+  });
+}

overlays/default.nix

@@ -21,6 +21,7 @@ let
     gobject-introspection = import ./gobject-introspection.nix;
     hix = import ./hix.nix;
     ghcjs = import ./ghcjs.nix;
+    cabalPkgConfig = import ./cabal-pkg-config.nix;
     default-setup = import ./default-setup.nix;
   };
 
@@ -52,6 +53,7 @@ let
     emscripten
     nix-prefetch-git-minimal
     ghcjs
+    cabalPkgConfig
     gobject-introspection
     hix
     hydra

test/exe-dlls/default.nix

@@ -7,7 +7,7 @@ let
   project = project' {
     inherit compiler-nix-name evalPackages;
     src = testSrc "exe-dlls";
-    pkgconfSelector = p: [p.libsodium];
+    pkgconfigSelector = p: [p.libsodium];
   };
 
   packages = project.hsPkgs;