buildGoModule: fix overrideAttrs overriding

Fix overriding of vendorHash and various attributes via the fixed point
attribute support of stdenv.mkDerivation.

Pass as derivation attributes
goModules, modRoot, vendorHash, deleteVendor, and proxyVendor.

Move goModules and vendorHash out of passthru.

Co-authored-by: Doron Behar <doron.behar@gmail.com>

doc/languages-frameworks/go.section.md

@@ -62,6 +62,65 @@ The following is an example expression using `buildGoModule`:
 }
 ```
 
+### Obtaining and overriding `vendorHash` for `buildGoModule` {#buildGoModule-vendorHash}
+
+We can use `nix-prefetch` to obtain the actual hash. The following command gets the value of `vendorHash` for package `pet`:
+
+```sh
+cd path/to/nixpkgs
+nix-prefetch -E "{ sha256 }: ((import ./. { }).my-package.overrideAttrs { vendorHash = sha256; }).goModules"
+```
+
+To obtain the hash without external tools, set `vendorHash = lib.fakeHash;` and run the build. ([more details here](#sec-source-hashes)).
+
+`vendorHash` can be overridden with `overrideAttrs`. Override the above example like this:
+
+```nix
+{
+  pet_0_4_0 = pet.overrideAttrs (
+    finalAttrs: previousAttrs: {
+      version = "0.4.0";
+      src = fetchFromGitHub {
+        inherit (previousAttrs.src) owner repo;
+        rev = "v${finalAttrs.version}";
+        hash = "sha256-gVTpzmXekQxGMucDKskGi+e+34nJwwsXwvQTjRO6Gdg=";
+      };
+      vendorHash = "sha256-dUvp7FEW09V0xMuhewPGw3TuAic/sD7xyXEYviZ2Ivs=";
+    }
+  );
+}
+```
+
+### Overriding `goModules` (#buildGoModule-goModules-override)
+
+Overriding `<pkg>.goModules` by calling `goModules.overrideAttrs` is unsupported. Still, it is possible to override the `vendorHash` (`goModules`'s `outputHash`) and the `pre`/`post` hooks for both the build and patch phases of the primary and `goModules` derivation. Alternatively, the primary derivation provides an overridable `passthru.overrideModAttrs` function to store the attribute overlay implicitly taken by `goModules.overrideAttrs`. Here's an example usage of `overrideModAttrs`:
+
+```nix
+{
+  pet-overridden = pet.overrideAttrs (
+    finalAttrs: previousAttrs: {
+      passthru = previousAttrs.passthru // {
+        # If the original package has an `overrideModAttrs` attribute set, you'd
+        # want to extend it, and not replace it. Hence we use
+        # `lib.composeExtensions`. If you are sure the `overrideModAttrs` of the
+        # original package trivially does nothing, you can safely replace it
+        # with your own by not using `lib.composeExtensions`.
+        overrideModAttrs = lib.composeExtensions previousAttrs.passthru.overrideModAttrs (
+          finalModAttrs: previousModAttrs: {
+            # goModules-specific overriding goes here
+            postBuild = ''
+              # Here you have access to the `vendor` directory.
+              substituteInPlace vendor/github.com/example/repo/file.go \
+                --replace-fail "panic(err)" ""
+            '';
+          }
+        );
+      };
+    }
+  );
+}
+```
+
 ## `buildGoPackage` (legacy) {#ssec-go-legacy}
 
 The function `buildGoPackage` builds legacy Go programs, not supporting Go modules.

nixos/doc/manual/release-notes/rl-2411.section.md

@@ -272,6 +272,10 @@
   [buildRustPackage: Compiling Rust applications with Cargo](https://nixos.org/manual/nixpkgs/unstable/#compiling-rust-applications-with-cargo)
   for more information.
 
+- The `vendorHash` of Go packages built with `buildGoModule` can now be overridden with `overrideAttrs`.
+  `goModules`, `modRoot`, `vendorHash`, `deleteVendor`, and `proxyVendor` are now passed as derivation attributes.
+  `goModules` and `vendorHash` are no longer placed t under `passthru`.
+
 - `hareHook` has been added as the language framework for Hare. From now on, it,
   not the `hare` package, should be added to `nativeBuildInputs` when building
   Hare programs.

pkgs/build-support/go/module.nix

@@ -7,7 +7,7 @@
 , patches ? [ ]
 
   # A function to override the goModules derivation
-, overrideModAttrs ? (_oldAttrs: { })
+, overrideModAttrs ? (finalAttrs: previousAttrs: { })
 
   # path to go.mod and go.sum directory
 , modRoot ? "./"
@@ -58,18 +58,38 @@
 assert goPackagePath != "" -> throw "`goPackagePath` is not needed with `buildGoModule`";
 
 let
-  args = removeAttrs args' [ "overrideModAttrs" "vendorSha256" "vendorHash" ];
+  args = removeAttrs args' [ "overrideModAttrs" "vendorSha256" ];
 
   GO111MODULE = "on";
   GOTOOLCHAIN = "local";
 
-  goModules = if (vendorHash == null) then "" else
+  toExtension =
+    overlay0:
+    if lib.isFunction overlay0 then
+      final: prev:
+      if lib.isFunction (overlay0 prev) then
+        # `overlay0` is `final: prev: { ... }`
+        overlay0 final prev
+      else
+        # `overlay0` is `prev: { ... }`
+        overlay0 prev
+    else
+      # `overlay0` is `{ ... }`
+      final: prev: overlay0;
+
+in
+(stdenv.mkDerivation (finalAttrs:
+  args
+  // {
+
+  inherit modRoot vendorHash deleteVendor proxyVendor;
+  goModules = if (finalAttrs.vendorHash == null) then "" else
   (stdenv.mkDerivation {
-    name = "${name}-go-modules";
+    name = "${finalAttrs.name or "${finalAttrs.pname}-${finalAttrs.version}"}-go-modules";
 
-    nativeBuildInputs = (args.nativeBuildInputs or [ ]) ++ [ go git cacert ];
+    nativeBuildInputs = (finalAttrs.nativeBuildInputs or [ ]) ++ [ go git cacert ];
 
-    inherit (args) src;
+    inherit (finalAttrs) src modRoot;
     inherit (go) GOOS GOARCH;
     inherit GO111MODULE GOTOOLCHAIN;
 
@@ -77,15 +97,15 @@ let
     # argue it's not ideal. Changing it may break vendor hashes in Nixpkgs and
     # out in the wild. In anycase, it's documented in:
     # doc/languages-frameworks/go.section.md
-    prePatch = args.prePatch or "";
-    patches = args.patches or [ ];
-    patchFlags = args.patchFlags or [ ];
-    postPatch = args.postPatch or "";
-    preBuild = args.preBuild or "";
-    postBuild = args.modPostBuild or "";
-    sourceRoot = args.sourceRoot or "";
-    setSourceRoot = args.setSourceRoot or "";
-    env = args.env or { };
+    prePatch = finalAttrs.prePatch or "";
+    patches = finalAttrs.patches or [ ];
+    patchFlags = finalAttrs.patchFlags or [ ];
+    postPatch = finalAttrs.postPatch or "";
+    preBuild = finalAttrs.preBuild or "";
+    postBuild = finalAttrs.modPostBuild or "";
+    sourceRoot = finalAttrs.sourceRoot or "";
+    setSourceRoot = finalAttrs.setSourceRoot or "";
+    env = finalAttrs.env or { };
 
     impureEnvVars = lib.fetchers.proxyImpureEnvVars ++ [
       "GIT_PROXY_COMMAND"
@@ -97,13 +117,13 @@ let
       runHook preConfigure
       export GOCACHE=$TMPDIR/go-cache
       export GOPATH="$TMPDIR/go"
-      cd "${modRoot}"
+      cd "$modRoot"
       runHook postConfigure
     '';
 
     buildPhase = args.modBuildPhase or (''
       runHook preBuild
-    '' + lib.optionalString deleteVendor ''
+    '' + lib.optionalString finalAttrs.deleteVendor ''
       if [ ! -d vendor ]; then
         echo "vendor folder does not exist, 'deleteVendor' is not needed"
         exit 10
@@ -116,7 +136,7 @@ let
         exit 10
       fi
 
-      ${if proxyVendor then ''
+      ${if finalAttrs.proxyVendor then ''
         mkdir -p "''${GOPATH}/pkg/mod/cache/download"
         go mod download
       '' else ''
@@ -134,7 +154,7 @@ let
     installPhase = args.modInstallPhase or ''
       runHook preInstall
 
-      ${if proxyVendor then ''
+      ${if finalAttrs.proxyVendor then ''
         rm -rf "''${GOPATH}/pkg/mod/cache/download/sumdb"
         cp -r --reflink=auto "''${GOPATH}/pkg/mod/cache/download" $out
       '' else ''
@@ -152,20 +172,19 @@ let
     dontFixup = true;
 
     outputHashMode = "recursive";
-    outputHash = vendorHash;
+    outputHash = finalAttrs.vendorHash;
     # Handle empty vendorHash; avoid
     # error: empty hash requires explicit hash algorithm
-    outputHashAlgo = if vendorHash == "" then "sha256" else null;
-  }).overrideAttrs overrideModAttrs;
+    outputHashAlgo = if finalAttrs.vendorHash == "" then "sha256" else null;
+  }).overrideAttrs finalAttrs.passthru.overrideModAttrs;
 
-  package = stdenv.mkDerivation (args // {
     nativeBuildInputs = [ go ] ++ nativeBuildInputs;
 
     inherit (go) GOOS GOARCH;
 
     GOFLAGS = GOFLAGS
       ++ lib.warnIf (lib.any (lib.hasPrefix "-mod=") GOFLAGS) "use `proxyVendor` to control Go module/vendor behavior instead of setting `-mod=` in GOFLAGS"
-        (lib.optional (!proxyVendor) "-mod=vendor")
+        (lib.optional (!finalAttrs.proxyVendor) "-mod=vendor")
       ++ lib.warnIf (builtins.elem "-trimpath" GOFLAGS) "`-trimpath` is added by default to GOFLAGS by buildGoModule when allowGoReference isn't set to true"
         (lib.optional (!allowGoReference) "-trimpath");
     inherit CGO_ENABLED enableParallelBuilding GO111MODULE GOTOOLCHAIN;
@@ -181,12 +200,12 @@ let
       export GOPROXY=off
       export GOSUMDB=off
       cd "$modRoot"
-    '' + lib.optionalString (vendorHash != null) ''
-      ${if proxyVendor then ''
-        export GOPROXY=file://${goModules}
+    '' + lib.optionalString (finalAttrs.vendorHash != null) ''
+      ${if finalAttrs.proxyVendor then ''
+        export GOPROXY="file://$goModules"
       '' else ''
         rm -rf vendor
-        cp -r --reflink=auto ${goModules} vendor
+        cp -r --reflink=auto "$goModules" vendor
       ''}
     '' + ''
 
@@ -307,12 +326,17 @@ let
 
     disallowedReferences = lib.optional (!allowGoReference) go;
 
-    passthru = { inherit go goModules vendorHash; } // passthru;
+    passthru = {
+      inherit go;
+      # Canonicallize `overrideModAttrs` as an attribute overlay.
+      # `passthru.overrideModAttrs` will be overridden
+      # when users want to override `goModules`.
+      overrideModAttrs = toExtension overrideModAttrs;
+    } // passthru;
 
     meta = {
       # Add default meta information
       platforms = go.meta.platforms or lib.platforms.all;
     } // meta;
-  });
-in
-package
+  }
+))

pkgs/test/overriding.nix

@@ -27,6 +27,38 @@ let
         expr = ((stdenvNoCC.mkDerivation { pname = "hello-no-final-attrs"; }).overrideAttrs { pname = "hello-no-final-attrs-overridden"; }).pname == "hello-no-final-attrs-overridden";
         expected = true;
       };
+      buildGoModule-overrideAttrs = {
+        expr = lib.all (
+          attrPath:
+          let
+            attrPathPretty = lib.concatStringsSep "." attrPath;
+            valueNative = lib.getAttrFromPath attrPath pet_0_4_0;
+            valueOverridden = lib.getAttrFromPath attrPath pet_0_4_0-overridden;
+          in
+          lib.warnIfNot
+            (valueNative == valueOverridden)
+            "pet_0_4_0.${attrPathPretty} (${valueNative}) does not equal pet_0_4_0-overridden.${attrPathPretty} (${valueOverridden})"
+            true
+        ) [
+          [ "drvPath" ]
+          [ "name" ]
+          [ "pname" ]
+          [ "version" ]
+          [ "vendorHash" ]
+          [ "goModules" "drvPath" ]
+          [ "goModules" "name" ]
+          [ "goModules" "outputHash" ]
+        ];
+        expected = true;
+      };
+      buildGoModule-goModules-overrideAttrs = {
+        expr = pet-foo.goModules.FOO == "foo";
+        expected = true;
+      };
+      buildGoModule-goModules-overrideAttrs-vendored = {
+        expr = lib.isString pet-vendored.drvPath;
+        expected = true;
+      };
     };
 
   addEntangled = origOverrideAttrs: f:
@@ -51,6 +83,74 @@ let
   overrides1 = example.overrideAttrs (_: super: { pname = "a-better-${super.pname}"; });
 
   repeatedOverrides = overrides1.overrideAttrs (_: super: { pname = "${super.pname}-with-blackjack"; });
+
+  pet_0_3_4 = pkgs.buildGoModule rec {
+    pname = "pet";
+    version = "0.3.4";
+
+    src = pkgs.fetchFromGitHub {
+      owner = "knqyf263";
+      repo = "pet";
+      rev = "v${version}";
+      hash = "sha256-Gjw1dRrgM8D3G7v6WIM2+50r4HmTXvx0Xxme2fH9TlQ=";
+    };
+
+    vendorHash = "sha256-ciBIR+a1oaYH+H1PcC8cD8ncfJczk1IiJ8iYNM+R6aA=";
+
+    meta = {
+      description = "Simple command-line snippet manager, written in Go";
+      homepage = "https://github.com/knqyf263/pet";
+      license = lib.licenses.mit;
+      maintainers = with lib.maintainers; [ kalbasit ];
+    };
+  };
+
+  pet_0_4_0 = pkgs.buildGoModule rec {
+    pname = "pet";
+    version = "0.4.0";
+
+    src = pkgs.fetchFromGitHub {
+      owner = "knqyf263";
+      repo = "pet";
+      rev = "v${version}";
+      hash = "sha256-gVTpzmXekQxGMucDKskGi+e+34nJwwsXwvQTjRO6Gdg=";
+    };
+
+    vendorHash = "sha256-dUvp7FEW09V0xMuhewPGw3TuAic/sD7xyXEYviZ2Ivs=";
+
+    meta = {
+      description = "Simple command-line snippet manager, written in Go";
+      homepage = "https://github.com/knqyf263/pet";
+      license = lib.licenses.mit;
+      maintainers = with lib.maintainers; [ kalbasit ];
+    };
+  };
+
+  pet_0_4_0-overridden = pet_0_3_4.overrideAttrs (finalAttrs: previousAttrs: {
+  version = "0.4.0";
+
+  src = pkgs.fetchFromGitHub {
+    inherit (previousAttrs.src) owner repo;
+    rev = "v${finalAttrs.version}";
+    hash = "sha256-gVTpzmXekQxGMucDKskGi+e+34nJwwsXwvQTjRO6Gdg=";
+  };
+
+  vendorHash = "sha256-dUvp7FEW09V0xMuhewPGw3TuAic/sD7xyXEYviZ2Ivs=";
+  });
+
+  pet-foo = pet_0_3_4.overrideAttrs (
+    finalAttrs: previousAttrs: {
+      passthru = previousAttrs.passthru // {
+        overrideModAttrs = lib.composeExtensions previousAttrs.passthru.overrideModAttrs (
+          finalModAttrs: previousModAttrs: {
+            FOO = "foo";
+          }
+        );
+      };
+    }
+  );
+
+  pet-vendored = pet-foo.overrideAttrs { vendorHash = null; };
 in
 
 stdenvNoCC.mkDerivation {