Merge pull request #52257 from shlevy/haskell-allow-inconsistent-dependencies

haskell generic builder: Add flag to allow inconsistent dependencies.

pkgs/development/haskell-modules/generic-builder.nix

@@ -74,6 +74,10 @@ in
 , hardeningDisable ? stdenv.lib.optional (ghc.isHaLVM or false) "all"
 , enableSeparateDataOutput ? false
 , enableSeparateDocOutput ? doHaddock
+, # Don't fail at configure time if there are multiple versions of the
+  # same package in the (recursive) dependencies of the package being
+  # built. Will delay failures, if any, to compile time.
+  allowInconsistentDependencies ? false
 } @ args:
 
 assert editedCabalFile != null -> revision != null;
@@ -336,11 +340,12 @@ stdenv.mkDerivation ({
 
     echo configureFlags: $configureFlags
     ${setupCommand} configure $configureFlags 2>&1 | ${coreutils}/bin/tee "$NIX_BUILD_TOP/cabal-configure.log"
+    ${stdenv.lib.optionalString (!allowInconsistentDependencies) ''
       if ${gnugrep}/bin/egrep -q -z 'Warning:.*depends on multiple versions' "$NIX_BUILD_TOP/cabal-configure.log"; then
         echo >&2 "*** abort because of serious configure-time warning from Cabal"
         exit 1
       fi
-
+    ''}
     export GHC_PACKAGE_PATH="$packageConfDir:"
 
     runHook postConfigure

pkgs/development/haskell-modules/lib.nix

@@ -408,4 +408,11 @@ rec {
   */
   generateOptparseApplicativeCompletions = commands: pkg:
     pkgs.lib.foldr generateOptparseApplicativeCompletion pkg commands;
+
+  # Don't fail at configure time if there are multiple versions of the
+  # same package in the (recursive) dependencies of the package being
+  # built. Will delay failures, if any, to compile time.
+  allowInconsistentDependencies = drv: overrideCabal drv (drv: {
+    allowInconsistentDependencies = true;
+  });
 }