Build nonReinstallablePkgs from pre-existing packages in plan.json (#2207)

Haskell.nix now respects the `pre-existing` packages selected
by the cabal planner.  The selection made by the planner
is used to set `nonReinstallablePkgs`.

Instead setting `nonReinstallablePkgs` and `reinstallableLibGhc`
haskell.nix projects should add `constraints` to the cabal project.

For instance to force the use of the `pre-exising` `text`
package add:

```
  constraints: text installed
```

To make sure `text` is reinstalled use:

```
  constraints: text source
```

The `pre-existing` `ghc` will now be used by default as
that is what `cabal` will choose (haskell.nix used to choose
`reinstallableLibGhc=true` by default).

To allow cabal to choose reinstalling `ghc` add:

```
  allow-boot-library-installs: True
```

To force cabal to choose reinstalling:

```
  constraints: ghc source
  allow-boot-library-installs: True
```

It may also need `allow-newer: ghc:Cabal`

Author: hamishmack

builder/make-config-files.nix

@@ -160,7 +160,7 @@ let
         fi
       ''}
     done
-    for p in ${lib.concatStringsSep " " (lib.remove "ghc" nonReinstallablePkgs')}; do
+    for p in ${lib.concatStringsSep " " nonReinstallablePkgs'}; do
       if [ -e $ghcDeps/envDeps/$p ]; then
         cat $ghcDeps/envDeps/$p >> $configFiles/ghc-environment
       fi

changelog.md

@@ -1,6 +1,47 @@
 This file contains a summary of changes to Haskell.nix and `nix-tools`
 that will impact users.
 
+## Jun 5, 2024
+
+Haskell.nix now respects the `pre-existing` packages selected
+by the cabal planner.  The selection made by the planner
+is used to set `nonReinstallablePkgs`.
+
+Instead setting `nonReinstallablePkgs` and `reinstallableLibGhc`
+haskell.nix projects should add `constraints` to the cabal project.
+
+For instance to force the use of the `pre-exising` `text`
+package add:
+
+```
+  constraints: text installed
+```
+
+To make sure `text` is reinstalled use:
+
+```
+  constraints: text source
+```
+
+The `pre-existing` `ghc` will now be used by default as
+that is what `cabal` will choose (haskell.nix used to choose
+`reinstallableLibGhc=true` by default).
+
+To allow cabal to choose reinstalling `ghc` add:
+
+```
+  allow-boot-library-installs: True
+```
+
+To force cabal to choose reinstalling:
+
+```
+  constraints: ghc source
+  allow-boot-library-installs: True
+```
+
+It may also need `allow-newer: ghc:Cabal`
+
 ## Mar 27, 2023
 
 Haskell.nix will no longer parse the `cabal.project` file to

compiler/ghc/default.nix

@@ -260,10 +260,16 @@ let
       materialized =
         if builtins.compareVersions ghc-version "9.4" < 0
           then ../../materialized/${compiler-nix-name}/hadrian-ghc92
+        else if builtins.compareVersions ghc-version "9.4.8" < 0
+          then ../../materialized/${compiler-nix-name}/hadrian-ghc947
         else if builtins.compareVersions ghc-version "9.6" < 0
           then ../../materialized/${compiler-nix-name}/hadrian-ghc94
+        else if builtins.compareVersions ghc-version "9.6.5" < 0
+          then ../../materialized/${compiler-nix-name}/hadrian-ghc964
         else if builtins.compareVersions ghc-version "9.8" < 0
           then ../../materialized/${compiler-nix-name}/hadrian-ghc96
+        else if builtins.compareVersions ghc-version "9.8.2" < 0
+          then ../../materialized/${compiler-nix-name}/hadrian-ghc981
         else if builtins.compareVersions ghc-version "9.9" < 0
           then ../../materialized/${compiler-nix-name}/hadrian-ghc98
         else ../../materialized/${compiler-nix-name}/hadrian-ghc99;

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

@@ -363,46 +363,49 @@ let
 
   ghc-pkgs = [
     "Cabal"
-    "Cabal-syntax"
     "array"
     "base"
     "binary"
     "bytestring"
     "containers"
     "deepseq"
     "directory"
-    "exceptions"
     "filepath"
-    "ghc"
-    "ghc-bignum"
     "ghc-boot"
     "ghc-boot-th"
     "ghc-compact"
-    "ghc-experimental"
     "ghc-heap"
-    "ghc-internal"
-    "ghc-platform"
     "ghc-prim"
-    "ghc-toolchain"
     "ghci"
-    "haskeline"
-    "hpc"
     "integer-gmp"
-    "libiserv"
     "mtl"
-    "os-string"
     "parsec"
     "pretty"
     "process"
     "rts"
-    "semaphore-compat"
-    "stm"
     "template-haskell"
-    "terminfo"
     "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"
+    "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" ]

lib/default.nix

@@ -340,7 +340,19 @@ in {
 
   # Converts from a `compoent.depends` value to a library derivation.
   # In the case of sublibs the `depends` value should already be the derivation.
-  dependToLib = d: d.components.library or d;
+  dependToLib = d:
+    # Do simplify this to `d.components.library or d`, as that
+    # will not give a good error message if the `.library`
+    # is missing (happens if the package is unplanned,
+    # but has overrides).
+    # It would be nice to put an `assert` here, but there is
+    # currently no good way to get the name of the dependency
+    # when it is not in the plan.  The attribute path of
+    # `d` in the `nix` error should include the name
+    # eg. `packages.Cabal.components.library`.
+    if d ? components
+      then d.components.library
+      else d;
 
   projectOverlays = import ./project-overlays.nix {
     inherit lib haskellLib;