Include all pre-existing ghc pkgs in shell, unless exactDeps (#2375)

Fixes #2168

Author: hamishmack

builder/default.nix

@@ -79,7 +79,7 @@ let
 
   # Same as haskellPackages.shellFor in nixpkgs.
   shellFor = haskellLib.weakCallPackage pkgs ./shell-for.nix {
-    inherit hsPkgs ghcForComponent makeConfigFiles hoogleLocal haskellLib pkgsBuildBuild evalPackages compiler;
+    inherit hsPkgs ghcForComponent makeConfigFiles hoogleLocal haskellLib pkgsBuildBuild evalPackages compiler ghc;
     inherit (buildPackages) glibcLocales;
   };
 

builder/shell-for.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, mkShell, glibcLocales, ghcForComponent, makeConfigFiles, hsPkgs, hoogleLocal, haskellLib, pkgsBuildBuild, evalPackages, compiler }:
+{ lib, stdenv, mkShell, glibcLocales, ghcForComponent, makeConfigFiles, hsPkgs, hoogleLocal, haskellLib, pkgsBuildBuild, evalPackages, compiler, haskell-nix, ghc }:
 
 { # `packages` function selects packages that will be worked on in the shell itself.
   # These packages will not be built by `shellFor`, but their
@@ -120,7 +120,10 @@ let
   # Set up a "dummy" component to use with ghcForComponent.
   component = {
     depends = packageInputs;
-    pre-existing = lib.unique (lib.concatMap (x: (haskellLib.dependToLib x).pre-existing or []) allConfigs);
+    pre-existing =
+      if exactDeps
+        then lib.unique (lib.concatMap (x: (haskellLib.dependToLib x).pre-existing or []) allConfigs)
+        else haskell-nix.ghc-pre-existing ghc;
     libs         = haskellLib.uniqueWithName (lib.concatMap (x: (haskellLib.dependToLib x).libs or []) allConfigs);
     pkgconfig    = haskellLib.uniqueWithName (lib.concatMap (x: (haskellLib.dependToLib x).pkgconfig or []) allConfigs);
     frameworks   = haskellLib.uniqueWithName (lib.concatMap (x: (haskellLib.dependToLib x).frameworks or []) allConfigs);

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

@@ -366,57 +366,6 @@ let
     '';
   };
 
-  ghc-pkgs = [
-    "Cabal"
-    "array"
-    "base"
-    "binary"
-    "bytestring"
-    "containers"
-    "deepseq"
-    "directory"
-    "filepath"
-    "ghc-boot"
-    "ghc-boot-th"
-    "ghc-compact"
-    "ghc-heap"
-    "ghc-prim"
-    "ghci"
-    "integer-gmp"
-    "mtl"
-    "parsec"
-    "pretty"
-    "process"
-    "rts"
-    "template-haskell"
-    "text"
-    "time"
-    "transformers"
-  ] ++ pkgs.lib.optionals (!pkgs.stdenv.targetPlatform.isGhcjs || builtins.compareVersions ghc.version "9.0" > 0) [
-    # GHCJS 8.10 does not have these
-    "Cabal-syntax"
-    "exceptions"
-    "file-io"
-    "ghc"
-    "ghc-bignum"
-    "ghc-experimental"
-    "ghc-internal"
-    "ghc-platform"
-    "ghc-toolchain"
-    "haskeline"
-    "hpc"
-    "libiserv"
-    "os-string"
-    "semaphore-compat"
-    "stm"
-    "xhtml"
-  ] ++ pkgs.lib.optionals (!pkgs.stdenv.targetPlatform.isGhcjs) [
-    "terminfo"
-  ] ++ (if pkgs.stdenv.targetPlatform.isWindows
-    then [ "Win32" ]
-    else [ "unix" ]
-  );
-
   dummy-ghc-pkg-dump = evalPackages.runCommand "dummy-ghc-pkg-dump" {
       nativeBuildInputs = [
         evalPackages.haskell-nix.nix-tools-unchecked.exes.cabal2json
@@ -557,7 +506,7 @@ let
                 PKGS+=" ${name}"
                 LAST_PKG="${name}"
               fi
-            '') ghc-pkgs)
+            '') (pkgs.haskell-nix.ghc-pre-existing ghc))
           }
           ${ # There is no .cabal file for system-cxx-std-lib
             pkgs.lib.optionalString (builtins.compareVersions ghc.version "9.2" >= 0) (

overlays/haskell.nix

@@ -1074,6 +1074,60 @@ final: prev: {
               };
             }) final.haskell-nix.compiler;
 
+          ghc-pre-existing = ghc: [
+            "Cabal"
+            "array"
+            "base"
+            "binary"
+            "bytestring"
+            "containers"
+            "deepseq"
+            "directory"
+            "filepath"
+            "ghc-boot"
+            "ghc-boot-th"
+            "ghc-compact"
+            "ghc-heap"
+            "ghc-prim"
+            "ghci"
+            "integer-gmp"
+            "mtl"
+            "parsec"
+            "pretty"
+            "process"
+            "rts"
+            "template-haskell"
+            "text"
+            "time"
+            "transformers"
+          ] ++ final.lib.optionals (!final.stdenv.targetPlatform.isGhcjs || builtins.compareVersions ghc.version "9.0" > 0) [
+            # GHCJS 8.10 does not have these
+            "Cabal-syntax"
+            "exceptions"
+            "file-io"
+            "ghc"
+            "ghc-bignum"
+            "ghc-experimental"
+            "ghc-internal"
+            "ghc-platform"
+            "ghc-toolchain"
+            "haskeline"
+            "hpc"
+            "libiserv"
+            "os-string"
+            "semaphore-compat"
+            "stm"
+            "xhtml"
+          ] ++ final.lib.optionals (
+                  !final.stdenv.targetPlatform.isGhcjs
+               && !final.stdenv.targetPlatform.isWindows
+               && ghc.enableTerminfo or true) [
+            "terminfo"
+          ] ++ (if final.stdenv.targetPlatform.isWindows
+            then [ "Win32" ]
+            else [ "unix" ]
+          );
+
         # Add this to your tests to make all the dependencies of haskell.nix
         # are tested and cached. Consider using `p.roots` where `p` is a
         # project as it will automatically match the `compiler-nix-name`