add DEVELOPER_DIR and SDKROOT

pkg/rbeconfigsgen/rbeconfigsgen.go

@@ -296,6 +296,68 @@ func genCppConfigs(r runner.Runner, o *options.Options, bazeliskPath string) (st
 	if err != nil {
 		return "", fmt.Errorf("unable to determine the build output directory where Bazel produced C++ configs in the runner: %w", err)
 	}
+
+	// extract DEVELOPER_DIR for MacOS runner
+	developerDir := ""
+	if o.ExecOS == options.OSMacos {
+		out, err := r.ExecCmd(bazeliskPath, "query", "@local_config_xcode//:host_xcodes", "--output", "build")
+		if err != nil {
+			return "", fmt.Errorf("`bazel query @local_config_xcode//:host_xcodes` fails in the runner: %w", err)
+		}
+		versionLabel := ""
+		for _, line := range strings.Split(out, "\n") {
+			// We're looking for a line that looks like `default = "@local_config_xcode//:<version>",` and we want to
+			// extract @local_config_xcode//:<version>.
+			split := strings.SplitN(line, "=", 2)
+			if len(split) != 2 {
+				continue
+			}
+			key := strings.TrimSpace(split[0])
+			val := strings.Trim(strings.TrimSpace(split[1]),"\",")
+			if key == "default" {
+				versionLabel = val
+			}
+		}
+		if len(versionLabel) == 0 {
+			return "", fmt.Errorf("target @local_config_xcode//:host_xcodes has no default version")
+		}
+
+		out, err = r.ExecCmd(bazeliskPath, "query", versionLabel, "--output", "build")
+		if err != nil {
+			return "", fmt.Errorf("`bazel query %s` fails in the runner: %w", versionLabel, err)
+		}
+		xcodeVersion := ""
+		for _, line := range strings.Split(out, "\n") {
+			// We're looking for a line that looks like `version = "<version>",` and we want to
+			// extract <version>.
+			split := strings.SplitN(line, "=", 2)
+			if len(split) != 2 {
+				continue
+			}
+			key := strings.TrimSpace(split[0])
+			val := strings.Trim(strings.TrimSpace(split[1]),"\",")
+			if key == "version" {
+				xcodeVersion = val
+			}
+		}
+		if len(xcodeVersion) == 0 {
+			return "", fmt.Errorf("target %s has no version attr", versionLabel)
+		}
+
+		xcodeLocatorPath := path.Join(bazelOutputRoot, "external", "local_config_xcode", "xcode-locator-bin")
+		out, err = r.ExecCmd(xcodeLocatorPath, xcodeVersion)
+		if err != nil {
+			return "", fmt.Errorf("`%s %s` fails in the runner: %w", xcodeLocatorPath, xcodeVersion, err)
+		}
+		// developerDir will be the last line
+		outLines := strings.Split(out, "\n")
+		developerDir = outLines[len(outLines)-1]
+		if developerDir == "" {
+			return "", fmt.Errorf("failed to find DEVELOPER_DIR")
+		}
+		log.Printf("DEVELOPER_DIR: '%s'.", developerDir)
+	}
+
 	cppConfigDir := path.Join(bazelOutputRoot, "external", o.CPPConfigRepo)
 	log.Printf("Extracting C++ config files generated by Bazel at %q from the runner.", cppConfigDir)
 
@@ -339,6 +401,40 @@ func genCppConfigs(r runner.Runner, o *options.Options, bazeliskPath string) (st
 		}
 	}
 
+	if o.ExecOS == options.OSMacos {
+		// w/a for the issue described here: https://github.com/bazelbuild/bazel/pull/13529
+		sedArgs := []string{
+			"-I",
+			"",
+			"-e",
+			"s|@local_config_cc_toolchains//:osx_archs.bzl|@bazel_tools//tools/osx/crosstool:osx_archs.bzl|",
+			path.Join(cppConfigDir, "BUILD"),
+		}
+		if _, err := r.ExecCmd("sed", sedArgs...); err != nil {
+			return "", fmt.Errorf("failed to replace osx_archs.bzl label in BUILD")
+		}
+		sdkRoot := path.Join(developerDir, "Platforms",
+			"%{apple_sdk_platform_value}.platform",
+			"Developer",
+			"SDKs",
+			"%{apple_sdk_platform_value}%{apple_sdk_version_override_value}.sdk",
+		)
+		sedArgs = []string{
+			"-I",
+			"",
+			"-e",
+			"/cc_toolchain_config(/ a\\\n" +
+				"        extra_env = { \\\n" +
+				"            \"DEVELOPER_DIR\": \"" + developerDir + "\",\\\n" +
+				"            \"SDKROOT\": \"" + sdkRoot + "\",\\\n" +
+			    "        },",
+			path.Join(cppConfigDir, "BUILD"),
+		}
+		if _, err := r.ExecCmd("sed", sedArgs...); err != nil {
+			return "", fmt.Errorf("failed to add extra_env to cc_toolchain_config in BUILD")
+		}
+	}
+
 	outputTarball := "cpp_configs.tar"
 	// Explicitly use absolute paths to avoid confusion on what's the working directory.
 	outputTarballPath := path.Join(o.TempWorkDir, outputTarball)