Fix "Multiple versions for Win32"

Author: hamishmack

lib/default.nix

@@ -103,7 +103,7 @@ in {
   # if it's a project package it has a src attribute set with an origSubDir attribute.
   # project packages are a subset of localPackages
   isProjectPackage = p: p.isProject or false;
-  selectProjectPackages = lib.filterAttrs (_n: p: p != null && isLocalPackage p && isProjectPackage p);
+  selectProjectPackages = lib.filterAttrs (n: p: p != null && !(p.isRedirect or false) && isLocalPackage p && isProjectPackage p);
 
   # Format a componentId as it should appear as a target on the
   # command line of the setup script.

overlays/haskell.nix

@@ -825,40 +825,47 @@ final: prev: {
                             byVersion = builtins.groupBy (x: x.pkg-version) packageTargets;
                             versions = builtins.attrNames byVersion;
                           in if builtins.length versions != 1
-                            then throw "Multiple versions for ${packageName} ${builtins.toJSON versions}"
+                            then let
+                                err = throw "Multiple versions for ${packageName} ${builtins.toJSON versions}";
+                              in {
+                                isRedirect = true;
+                                identifier = { name = packageName; version = err; };
+                                components = err;
+                                checks = err;
+                              }
                             else let
-                              componentsByName = builtins.listToAttrs (map (x: { name = x.component-name; value = x.available; }) packageTargets);
-                              lookupComponent = collectionName: name: available:
-                                let attrPath =
-                                  if collectionName == ""
-                                    then "${packageName}.components.library"
-                                    else "${packageName}.components.${collectionName}.${name}";
-                                in if builtins.length available != 1
-                                  then throw "Multiple avaialble targets for ${attrPath}"
-                                else if builtins.isString (builtins.head available)
-                                  then throw "${builtins.head available} looking for ${attrPath}"
-                                else if collectionName == ""
-                                  then config.hsPkgs.${(builtins.head available).id}.components.library
-                                else config.hsPkgs.${(builtins.head available).id}.components.${collectionName}.${name};
-                              componentsWithPrefix = collectionName: prefix:
-                                final.lib.listToAttrs (final.lib.concatLists (final.lib.mapAttrsToList (n: available:
-                                  final.lib.optional (final.lib.hasPrefix "${prefix}:" n && (builtins.length available != 1 || !builtins.elem (builtins.head available) ["TargetNotBuildable" "TargetNotLocal"])) (
-                                    let
-                                      name = final.lib.removePrefix "${prefix}:" n;
-                                      value = lookupComponent collectionName name available;
-                                    in { inherit name value; }
-                                  )) componentsByName));
-                            in rec {
-                                identifier = { name = packageName; version = builtins.head versions; };
-                                components =
-                                  final.lib.mapAttrs componentsWithPrefix haskellLib.componentPrefix
-                                  // final.lib.optionalAttrs (componentsByName ? lib) {
-                                    library = lookupComponent "" "" componentsByName.lib;
-                                  };
-                                checks = final.recurseIntoAttrs (builtins.mapAttrs
-                                  (_: d: haskellLib.check d)
-                                    (final.lib.filterAttrs (_: d: d.config.doCheck) components.tests));
-                              })
+                                componentsByName = builtins.listToAttrs (map (x: { name = x.component-name; value = x.available; }) packageTargets);
+                                lookupComponent = collectionName: name: available:
+                                  let attrPath =
+                                    if collectionName == ""
+                                      then "${packageName}.components.library"
+                                      else "${packageName}.components.${collectionName}.${name}";
+                                  in if builtins.length available != 1
+                                    then throw "Multiple avaialble targets for ${attrPath}"
+                                  else if builtins.isString (builtins.head available)
+                                    then throw "${builtins.head available} looking for ${attrPath}"
+                                  else if collectionName == ""
+                                    then config.hsPkgs.${(builtins.head available).id}.components.library
+                                  else config.hsPkgs.${(builtins.head available).id}.components.${collectionName}.${name};
+                                componentsWithPrefix = collectionName: prefix:
+                                  final.lib.listToAttrs (final.lib.concatLists (final.lib.mapAttrsToList (n: available:
+                                    final.lib.optional (final.lib.hasPrefix "${prefix}:" n && (builtins.length available != 1 || !builtins.elem (builtins.head available) ["TargetNotBuildable" "TargetNotLocal"])) (
+                                      let
+                                        name = final.lib.removePrefix "${prefix}:" n;
+                                        value = lookupComponent collectionName name available;
+                                      in { inherit name value; }
+                                    )) componentsByName));
+                              in rec {
+                                  identifier = { name = packageName; version = builtins.head versions; };
+                                  components =
+                                    final.lib.mapAttrs componentsWithPrefix haskellLib.componentPrefix
+                                    // final.lib.optionalAttrs (componentsByName ? lib) {
+                                      library = lookupComponent "" "" componentsByName.lib;
+                                    };
+                                  checks = final.recurseIntoAttrs (builtins.mapAttrs
+                                    (_: d: haskellLib.check d)
+                                      (final.lib.filterAttrs (_: d: d.config.doCheck) components.tests));
+                                })
                               (builtins.groupBy (x: x.pkg-name) plan-json.targets)) config.preExistingPkgs;
                     })
                   ];