go_download_sdk: allow patching to stdlib

go/private/sdk.bzl

@@ -24,6 +24,61 @@ load(
     "//go/private/skylib/lib:versions.bzl",
     "versions",
 )
+load(
+    "@bazel_tools//tools/build_defs/repo:utils.bzl",
+    "patch",
+)
+
+patch_attrs = {
+    "patches": attr.label_list(
+        default = [],
+        doc =
+            "A list of files that are to be applied as patches after " +
+            "extracting the archive. By default, it uses the Bazel-native patch implementation " +
+            "which doesn't support fuzz match and binary patch, but Bazel will fall back to use " +
+            "patch command line tool if `patch_tool` attribute is specified or there are " +
+            "arguments other than `-p` in `patch_args` attribute.",
+    ),
+    "remote_patches": attr.string_dict(
+        default = {},
+        doc =
+            "A map of patch file URL to its integrity value, they are applied after extracting " +
+            "the archive and before applying patch files from the `patches` attribute. " +
+            "It uses the Bazel-native patch implementation, you can specify the patch strip " +
+            "number with `remote_patch_strip`",
+    ),
+    "remote_patch_strip": attr.int(
+        default = 0,
+        doc =
+            "The number of leading slashes to be stripped from the file name in the remote patches.",
+    ),
+    "patch_tool": attr.string(
+        default = "",
+        doc = "The patch(1) utility to use. If this is specified, Bazel will use the specified " +
+              "patch tool instead of the Bazel-native patch implementation.",
+    ),
+    "patch_args": attr.string_list(
+        default = ["-p0"],
+        doc =
+            "The arguments given to the patch tool. Defaults to -p0, " +
+            "however -p1 will usually be needed for patches generated by " +
+            "git. If multiple -p arguments are specified, the last one will take effect." +
+            "If arguments other than -p are specified, Bazel will fall back to use patch " +
+            "command line tool instead of the Bazel-native patch implementation. When falling " +
+            "back to patch command line tool and patch_tool attribute is not specified, " +
+            "`patch` will be used. This only affects patch files in the `patches` attribute.",
+    ),
+    "patch_cmds": attr.string_list(
+        default = [],
+        doc = "Sequence of Bash commands to be applied on Linux/Macos after patches are applied.",
+    ),
+    "patch_cmds_win": attr.string_list(
+        default = [],
+        doc = "Sequence of Powershell commands to be applied on Windows after patches are " +
+              "applied. If this attribute is not set, patch_cmds will be executed on Windows, " +
+              "which requires Bash binary to exist.",
+    ),
+}
 
 MIN_SUPPORTED_VERSION = (1, 14, 0)
 
@@ -37,15 +92,15 @@ def _go_host_sdk_impl(ctx):
 go_host_sdk_rule = repository_rule(
     implementation = _go_host_sdk_impl,
     environ = ["GOROOT"],
-    attrs = {
+    attrs = dict({
         "version": attr.string(),
         "experiments": attr.string_list(
             doc = "Go experiments to enable via GOEXPERIMENT",
         ),
         "_sdk_build_file": attr.label(
             default = Label("//go/private:BUILD.sdk.bazel"),
         ),
-    },
+    }, **patch_attrs),
 )
 
 def go_host_sdk(name, register_toolchains = True, **kwargs):
@@ -136,7 +191,7 @@ def _go_download_sdk_impl(ctx):
 
 go_download_sdk_rule = repository_rule(
     implementation = _go_download_sdk_impl,
-    attrs = {
+    attrs = dict({
         "goos": attr.string(),
         "goarch": attr.string(),
         "sdks": attr.string_list_dict(),
@@ -149,7 +204,7 @@ go_download_sdk_rule = repository_rule(
         "_sdk_build_file": attr.label(
             default = Label("//go/private:BUILD.sdk.bazel"),
         ),
-    },
+    }, **patch_attrs),
 )
 
 def _define_version_constants(version, prefix = ""):
@@ -325,7 +380,7 @@ def _go_local_sdk_impl(ctx):
 
 _go_local_sdk = repository_rule(
     implementation = _go_local_sdk_impl,
-    attrs = {
+    attrs = dict({
         "path": attr.string(),
         "version": attr.string(),
         "experiments": attr.string_list(
@@ -334,7 +389,7 @@ _go_local_sdk = repository_rule(
         "_sdk_build_file": attr.label(
             default = Label("//go/private:BUILD.sdk.bazel"),
         ),
-    },
+    }, **patch_attrs),
 )
 
 def go_local_sdk(name, register_toolchains = True, **kwargs):
@@ -371,7 +426,7 @@ def _go_wrap_sdk_impl(ctx):
 
 _go_wrap_sdk = repository_rule(
     implementation = _go_wrap_sdk_impl,
-    attrs = {
+    attrs = dict({
         "root_file": attr.label(
             mandatory = False,
             doc = "A file in the SDK root direcotry. Used to determine GOROOT.",
@@ -387,7 +442,7 @@ _go_wrap_sdk = repository_rule(
         "_sdk_build_file": attr.label(
             default = Label("//go/private:BUILD.sdk.bazel"),
         ),
-    },
+    }, **patch_attrs),
 )
 
 def go_wrap_sdk(name, register_toolchains = True, **kwargs):
@@ -478,6 +533,8 @@ def _sdk_build_file(ctx, platform, version, experiments):
         if not "nocoverageredesign" in experiments and not "coverageredesign" in experiments:
             experiments = experiments + ["nocoverageredesign"]
 
+    patch(ctx)
+
     ctx.template(
         "BUILD.bazel",
         ctx.path(ctx.attr._sdk_build_file),