cc_binary: support .dSYM generation

benjivos · benjivos · commit b800f3787ddf · 2025-04-22T17:00:45.000+02:00
Add support for generating a .dSYM file if this is requested using `--apple_generate_dsym`. This change contains the following patches: * Add `-fdebug-prefix-map` and `-oso_prefix` compiler and linker flags as in more recent Xcode versions (16E140) it would cause sandbox paths leaking into the linked binaries. * Add `DSYM_HINT` flags to be picked up by `wrapped_clang` to generate .dSYM bundles on request. * In `wrapped_clang.cc` make sure the linked binary is stripped after generating the .dSYM bundle first to make the .dSYM bundle contain useful information. Adopts recent changes in bazel to support .dSYM files (as part of fixing bazelbuild/bazel#16893).
diff --git a/crosstool/cc_toolchain_config.bzl b/crosstool/cc_toolchain_config.bzl
@@ -861,7 +861,7 @@ please file an issue at https://github.com/bazelbuild/apple_support/issues/new
                 actions = _DYNAMIC_LINK_ACTIONS,
                 flag_groups = [
                     flag_group(
-                        flags = ["-Wl,-S"],
+                        flags = ["STRIP_DEBUG_SYMBOLS"],
                         expand_if_available = "strip_debug_symbols",
                     ),
                 ],
@@ -2059,13 +2059,14 @@ please file an issue at https://github.com/bazelbuild/apple_support/issues/new
                 flag_groups = [flag_group(flags = ["-g"])],
             ),
             flag_set(
-                actions = ["objc-executable"],
+                actions = _DYNAMIC_LINK_ACTIONS,
                 flag_groups = [
                     flag_group(
                         flags = [
-                            "DSYM_HINT_LINKED_BINARY=%{linked_binary}",
+                            "DSYM_HINT_LINKED_BINARY=%{output_execpath}",
                             "DSYM_HINT_DSYM_PATH=%{dsym_path}",
                         ],
+                        expand_if_available = "output_execpath",
                     ),
                 ],
             ),
diff --git a/crosstool/wrapped_clang.cc b/crosstool/wrapped_clang.cc
@@ -261,14 +261,15 @@ void ProcessArgument(const std::string arg, const std::string developer_dir,
                      const std::string sdk_root, const std::string cwd,
                      const std::string nosandbox_root, bool relative_ast_path,
                      std::string &linked_binary, std::string &dsym_path,
-                     std::string toolchain_path,
+                     bool &strip_debug_symbols, std::string toolchain_path,
                      std::function<void(const std::string &)> consumer);
 
 bool ProcessResponseFile(const std::string arg, const std::string developer_dir,
                          const std::string sdk_root, const std::string cwd,
                          const std::string nosandbox_root,
                          bool relative_ast_path, std::string &linked_binary,
-                         std::string &dsym_path, std::string toolchain_path,
+                         std::string &dsym_path, bool &strip_debug_symbols,
+                         std::string toolchain_path,
                          std::function<void(const std::string &)> consumer) {
   auto path = arg.substr(1);
   std::ifstream original_file(path);
@@ -283,7 +284,7 @@ bool ProcessResponseFile(const std::string arg, const std::string developer_dir,
     // unescape them ourselves.
     ProcessArgument(Unescape(arg_from_file), developer_dir, sdk_root, cwd,
                     nosandbox_root, relative_ast_path, linked_binary, dsym_path,
-                    toolchain_path, consumer);
+                    strip_debug_symbols, toolchain_path, consumer);
   }
 
   return true;
@@ -341,13 +342,13 @@ void ProcessArgument(const std::string arg, const std::string developer_dir,
                      const std::string sdk_root, const std::string cwd,
                      const std::string nosandbox_root, bool relative_ast_path,
                      std::string &linked_binary, std::string &dsym_path,
-                     std::string toolchain_path,
+                     bool &strip_debug_symbols, std::string toolchain_path,
                      std::function<void(const std::string &)> consumer) {
   auto new_arg = arg;
   if (arg[0] == '@') {
     if (ProcessResponseFile(arg, developer_dir, sdk_root, cwd, nosandbox_root,
                             relative_ast_path, linked_binary, dsym_path,
-                            toolchain_path, consumer)) {
+                            strip_debug_symbols, toolchain_path, consumer)) {
       return;
     }
   }
@@ -358,6 +359,10 @@ void ProcessArgument(const std::string arg, const std::string developer_dir,
   if (SetArgIfFlagPresent(arg, "DSYM_HINT_DSYM_PATH", &dsym_path)) {
     return;
   }
+  if (arg == "STRIP_DEBUG_SYMBOLS") {
+    strip_debug_symbols = true;
+    return;
+  }
 
   FindAndReplace("__BAZEL_EXECUTION_ROOT__", cwd, &new_arg);
   FindAndReplace("__BAZEL_EXECUTION_ROOT_NO_SANDBOX__", nosandbox_root,
@@ -427,6 +432,7 @@ int main(int argc, char *argv[]) {
   std::string developer_dir = GetMandatoryEnvVar("DEVELOPER_DIR");
   std::string sdk_root = GetMandatoryEnvVar("SDKROOT");
   std::string linked_binary, dsym_path;
+  bool strip_debug_symbols = false;
 
   const std::string cwd = GetCurrentDirectory();
   std::vector<std::string> invocation_args = {"/usr/bin/xcrun", tool_name};
@@ -453,8 +459,8 @@ int main(int argc, char *argv[]) {
     std::string arg(argv[i]);
 
     ProcessArgument(arg, developer_dir, sdk_root, cwd, nosandbox_root,
-                    relative_ast_path, linked_binary, dsym_path, toolchain_path,
-                    consumer);
+                    relative_ast_path, linked_binary, dsym_path,
+                    strip_debug_symbols, toolchain_path, consumer);
   }
 
   char *modulemap = getenv("APPLE_SUPPORT_MODULEMAP");
@@ -509,16 +515,32 @@ int main(int argc, char *argv[]) {
     return 0;
   }
 
-  std::vector<std::string> dsymutil_args = {"/usr/bin/xcrun",
-                                            "dsymutil",
-                                            linked_binary,
-                                            "-o",
-                                            dsym_path,
-                                            "--flat",
-                                            "--no-swiftmodule-timestamp"};
+  const std::string bundle_suffix = ".dSYM";
+  bool is_bundle = dsym_path.rfind(bundle_suffix) ==
+                   dsym_path.length() - bundle_suffix.length();
+
+  std::vector<std::string> dsymutil_args = {
+      "/usr/bin/xcrun", "dsymutil",
+      linked_binary,    "-o",
+      dsym_path,        "--no-swiftmodule-timestamp"};
+  if (!is_bundle) {
+    // We should generate a .dSYM bundle only when a path is passed to a .dSYM
+    // directory for backwards compatibility
+    dsymutil_args.push_back("--flat");
+  }
   if (!RunSubProcess(dsymutil_args)) {
     return 1;
   }
 
+  // When stripping is requested, we should still strip the binary
+  // before returning
+  if (strip_debug_symbols) {
+    std::vector<std::string> strip_args = {"/usr/bin/xcrun", "strip", "-S",
+                                           linked_binary};
+    if (!RunSubProcess(strip_args)) {
+      return 2;
+    }
+  }
+
   return 0;
 }
diff --git a/test/linking_tests.bzl b/test/linking_tests.bzl
@@ -187,3 +187,16 @@ def linking_test_suite(name):
         mnemonic = "ObjcLink",
         target_under_test = "//test/test_data:macos_binary",
     )
+
+    dsym_test(
+        name = "{}_generate_cpp_dsym_test".format(name),
+        tags = [name] +
+               # Can't be enabled until https://github.com/bazelbuild/bazel/pull/25881 lands
+               ["manual"],
+        expected_argv = [
+            "DSYM_HINT_LINKED_BINARY",
+            "DSYM_HINT_DSYM_PATH",
+        ],
+        mnemonic = "CppLink",
+        target_under_test = "//test/test_data:cc_test_binary",
+    )
