[go_sdk download] allow patches to standard library

go/private/BUILD.bazel

@@ -107,6 +107,7 @@ bzl_library(
         "//go/private:nogo",
         "//go/private:platforms",
         "//go/private/skylib/lib:versions",
+        "@bazel_tools//tools/build_defs/repo:utils.bzl",
     ],
 )
 

go/private/extensions.bzl

@@ -31,6 +31,13 @@ _download_tag = tag_class(
         ),
         "urls": attr.string_list(default = ["https://dl.google.com/go/{}"]),
         "version": attr.string(),
+        "patches": attr.label_list(
+            doc = "A list of patches to apply to the SDK after downloading it",
+        ),
+        "patch_strip": attr.int(
+            default = 0,
+            doc = "The number of leading path segments to be stripped from the file name in the patches.",
+        ),
         "strip_prefix": attr.string(default = "go"),
     },
 )
@@ -93,6 +100,8 @@ def _go_sdk_impl(ctx):
                 goarch = download_tag.goarch,
                 sdks = download_tag.sdks,
                 experiments = download_tag.experiments,
+                patches = download_tag.patches,
+                patch_args = _get_patch_args(download_tag.patch_strip),
                 urls = download_tag.urls,
                 version = download_tag.version,
                 strip_prefix = download_tag.strip_prefix,
@@ -184,6 +193,11 @@ def _left_pad_zero(index, length):
         fail("index must be non-negative")
     return ("0" * length + str(index))[-length:]
 
+def _get_patch_args(patch_strip):
+    if patch_strip:
+        return ["-p{}".format(patch_strip)]
+    return []
+
 go_sdk = module_extension(
     implementation = _go_sdk_impl,
     tag_classes = {

go/private/sdk.bzl

@@ -12,18 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-load(
-    "//go/private:common.bzl",
-    "executable_path",
-)
-load(
-    "//go/private:nogo.bzl",
-    "go_register_nogo",
-)
-load(
-    "//go/private/skylib/lib:versions.bzl",
-    "versions",
-)
+load("//go/private:common.bzl", "executable_path")
+load("//go/private:nogo.bzl", "go_register_nogo")
+load("//go/private/skylib/lib:versions.bzl", "versions")
+load("@bazel_tools//tools/build_defs/repo:utils.bzl", "patch")
 
 MIN_SUPPORTED_VERSION = (1, 14, 0)
 
@@ -97,6 +89,8 @@ def _go_download_sdk_impl(ctx):
         sdks_by_version = _parse_versions_json(data)
 
         if not version:
+            if ctx.attr.patches:
+                fail("version must be specified when patches are specified")
             highest_version = None
             for v in sdks_by_version.keys():
                 pv = parse_version(v)
@@ -115,7 +109,9 @@ def _go_download_sdk_impl(ctx):
     if platform not in sdks:
         fail("unsupported platform {}".format(platform))
     filename, sha256 = sdks[platform]
+
     _remote_sdk(ctx, [url.format(filename) for url in ctx.attr.urls], ctx.attr.strip_prefix, sha256)
+    patch(ctx)
 
     detected_version = _detect_sdk_version(ctx, ".")
     _sdk_build_file(ctx, platform, detected_version, experiments = ctx.attr.experiments)
@@ -146,6 +142,13 @@ go_download_sdk_rule = repository_rule(
         "urls": attr.string_list(default = ["https://dl.google.com/go/{}"]),
         "version": attr.string(),
         "strip_prefix": attr.string(default = "go"),
+        "patches": attr.label_list(
+            doc = "A list of patches to apply to the SDK after downloading it",
+        ),
+        "patch_args": attr.string_list(
+            default = ["-p0"],
+            doc = "Arguments passed to the patch tool when applying patches.",
+        ),
         "_sdk_build_file": attr.label(
             default = Label("//go/private:BUILD.sdk.bazel"),
         ),

tests/bcr/BUILD.bazel

@@ -19,6 +19,11 @@ go_test(
     embed = [":lib"],
 )
 
+go_test(
+    name = "sdk_patch_test",
+    srcs = ["sdk_patch_test.go"],
+)
+
 go_library(
     name = "mockable",
     srcs = [

tests/bcr/MODULE.bazel

@@ -22,7 +22,13 @@ bazel_dep(name = "gazelle", version = "0.32.0")
 bazel_dep(name = "protobuf", version = "3.19.6")
 
 go_sdk = use_extension("@my_rules_go//go:extensions.bzl", "go_sdk")
-go_sdk.download(version = "1.19.5")
+go_sdk.download(
+    version = "1.21.1",
+    patch_strip = 1,
+    patches = [
+        "//:test_go_sdk.patch",
+    ],
+)
 
 # Request an invalid SDK to verify that it isn't fetched since the first tag takes precedence.
 go_sdk.host(version = "3.0.0")

tests/bcr/sdk_patch_test.go

@@ -0,0 +1,13 @@
+package lib
+
+import (
+	"os"
+
+	"testing"
+)
+
+func TestName(t *testing.T) {
+	if os.SayHello != "Hello" {
+		t.Fail()
+	}
+}

tests/bcr/test_go_sdk.patch

@@ -0,0 +1,13 @@
+diff --git a/src/os/dir.go b/src/os/dir.go
+index 5306bcb..d110a19 100644
+--- a/src/os/dir.go
++++ b/src/os/dir.go
+@@ -17,6 +17,8 @@ const (
+ 	readdirFileInfo
+ )
+
++const SayHello = "Hello"
++
+ // Readdir reads the contents of the directory associated with file and
+ // returns a slice of up to n FileInfo values, as would be returned
+ // by Lstat, in directory order. Subsequent calls on the same file will yield

tests/core/go_download_sdk/go_download_sdk_test.go

@@ -58,6 +58,7 @@ func Test(t *testing.T) {
 		desc, rule       string
 		optToWantVersion map[string]string
 		fetchOnly        string
+		patchContent string
 	}{
 		{
 			desc: "version",
@@ -89,6 +90,44 @@ go_download_sdk(
 `,
 			optToWantVersion: map[string]string{"": "go1.16"},
 		},
+		{
+			desc: "custom_archives_with_patch",
+			rule: `
+load("@io_bazel_rules_go//go:deps.bzl", "go_download_sdk")
+
+go_download_sdk(
+    name = "go_sdk",
+    sdks = {
+        "darwin_amd64": ("go1.16.darwin-amd64.tar.gz", "6000a9522975d116bf76044967d7e69e04e982e9625330d9a539a8b45395f9a8"),
+        "darwin_arm64": ("go1.16.darwin-arm64.tar.gz", "4dac57c00168d30bbd02d95131d5de9ca88e04f2c5a29a404576f30ae9b54810"),
+        "linux_amd64": ("go1.16.linux-amd64.tar.gz", "013a489ebb3e24ef3d915abe5b94c3286c070dfe0818d5bca8108f1d6e8440d2"),
+        "windows_amd64": ("go1.16.windows-amd64.zip", "5cc88fa506b3d5c453c54c3ea218fc8dd05d7362ae1de15bb67986b72089ce93"),
+    },
+    patch_args = ["-p1"],
+    patches = [
+        "//:test.patch",
+    ],
+)
+`,
+			optToWantVersion: map[string]string{"": "go-test"},
+			patchContent: `diff --git a/src/runtime/extern.go b/src/runtime/extern.go
+index dacdf4f..1b53d0d 100644
+--- a/src/runtime/extern.go
++++ b/src/runtime/extern.go
+@@ -244,7 +244,7 @@ func GOROOT() string {
+ // Version returns the Go tree's version string.
+ // It is either the commit hash and date at the time of the build or,
+ // when possible, a release tag like "go1.3".
+ func Version() string {
+-	return sys.TheVersion
++	return "go-test"
+ }
+
+ // GOOS is the running program's operating system target:
+ // one of darwin, freebsd, linux, and so on.
+ // To view possible combinations of GOOS and GOARCH, run "go tool dist list".
+ `,
+		},
 		{
 			desc: "multiple_sdks",
 			rule: `
@@ -154,6 +193,11 @@ go_register_toolchains()
 			if err := ioutil.WriteFile("WORKSPACE", buf.Bytes(), 0666); err != nil {
 				t.Fatal(err)
 			}
+			if test.patchContent != "" {
+				if err := ioutil.WriteFile("test.patch", []byte(test.patchContent), 0666); err != nil {
+					t.Fatal(err)
+				}
+			}
 			defer func() {
 				if err := ioutil.WriteFile("WORKSPACE", origWorkspaceData, 0666); err != nil {
 					t.Errorf("error restoring WORKSPACE: %v", err)