From bf388d55142f320b67accf14ff7103c370397515 Mon Sep 17 00:00:00 2001
From: sternenseemann <sternenseemann@systemli.org>
Date: Wed, 2 Aug 2023 12:30:10 +0200
Subject: [PATCH] haskell.compiler.ghc*Binary: make sure meta can always be
 evaluated

The `meta` set of the binary GHCs is mostly independent of the used
bindist (except for `pname` which includes `variantSuffix`). Thus we
should make sure it can be evaluated even if no bindist is available for
the platform, i.e. evaluating `outPath` may cause an evaluation failure,
but `meta.platforms` not. Use case at present is to make
`lib.meta.availableOn` work everywhere for any GHC (the normal GHCs
inherit their platforms list from their respective boot compiler, at
least for now).

To fix this we need to make sure that shallowly evaluating `passthru`
doesn't force `binDistUsed`, since `mkDerivation` needs to merge
`passthru` into the resulting derivation attribute set, thus forcing the
attribute names of `passthru`. We can easily do this by accessing what
we want to learn from `ghcBinDists` manually and using `or` to fall back
to a sensible default.
---
 pkgs/development/compilers/ghc/8.10.2-binary.nix | 5 ++++-
 pkgs/development/compilers/ghc/8.10.7-binary.nix | 5 ++++-
 pkgs/development/compilers/ghc/9.2.4-binary.nix  | 5 ++++-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/pkgs/development/compilers/ghc/8.10.2-binary.nix b/pkgs/development/compilers/ghc/8.10.2-binary.nix
index 41461a26d425..368bc76bf0e2 100644
--- a/pkgs/development/compilers/ghc/8.10.2-binary.nix
+++ b/pkgs/development/compilers/ghc/8.10.2-binary.nix
@@ -421,7 +421,10 @@ stdenv.mkDerivation rec {
 
     # Our Cabal compiler name
     haskellCompilerName = "ghc-${version}";
-  } // lib.optionalAttrs (binDistUsed.isHadrian or false) {
+  }
+  # We duplicate binDistUsed here since we have a sensible default even if no bindist is avaible,
+  # this makes sure that getting the `meta` attribute doesn't throw even on unsupported platforms.
+  // lib.optionalAttrs (ghcBinDists.${distSetName}.${stdenv.hostPlatform.system}.isHadrian or false) {
     # Normal GHC derivations expose the hadrian derivation used to build them
     # here. In the case of bindists we just make sure that the attribute exists,
     # as it is used for checking if a GHC derivation has been built with hadrian.
diff --git a/pkgs/development/compilers/ghc/8.10.7-binary.nix b/pkgs/development/compilers/ghc/8.10.7-binary.nix
index 22552fa67fb2..73ce0c918574 100644
--- a/pkgs/development/compilers/ghc/8.10.7-binary.nix
+++ b/pkgs/development/compilers/ghc/8.10.7-binary.nix
@@ -417,7 +417,10 @@ stdenv.mkDerivation rec {
 
     # Our Cabal compiler name
     haskellCompilerName = "ghc-${version}";
-  } // lib.optionalAttrs (binDistUsed.isHadrian or false) {
+  }
+  # We duplicate binDistUsed here since we have a sensible default even if no bindist is avaible,
+  # this makes sure that getting the `meta` attribute doesn't throw even on unsupported platforms.
+  // lib.optionalAttrs (ghcBinDists.${distSetName}.${stdenv.hostPlatform.system}.isHadrian or false) {
     # Normal GHC derivations expose the hadrian derivation used to build them
     # here. In the case of bindists we just make sure that the attribute exists,
     # as it is used for checking if a GHC derivation has been built with hadrian.
diff --git a/pkgs/development/compilers/ghc/9.2.4-binary.nix b/pkgs/development/compilers/ghc/9.2.4-binary.nix
index 79b006ce5537..93380fd14519 100644
--- a/pkgs/development/compilers/ghc/9.2.4-binary.nix
+++ b/pkgs/development/compilers/ghc/9.2.4-binary.nix
@@ -403,7 +403,10 @@ stdenv.mkDerivation rec {
 
     # Our Cabal compiler name
     haskellCompilerName = "ghc-${version}";
-  } // lib.optionalAttrs (binDistUsed.isHadrian or false) {
+  }
+  # We duplicate binDistUsed here since we have a sensible default even if no bindist is avaible,
+  # this makes sure that getting the `meta` attribute doesn't throw even on unsupported platforms.
+  // lib.optionalAttrs (ghcBinDists.${distSetName}.${stdenv.hostPlatform.system}.isHadrian or false) {
     # Normal GHC derivations expose the hadrian derivation used to build them
     # here. In the case of bindists we just make sure that the attribute exists,
     # as it is used for checking if a GHC derivation has been built with hadrian.