[clang] use relative paths for builtin headers during module compilation (#68023)

When including builtin headers as part of a system module, ensure we use
relative paths to those headers. Otherwise the module will fail to compile 
when specifying relative resource directories without extra search paths.

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index eb7cab5..e4f3cdd 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -348,8 +348,8 @@ bool ModuleMap::resolveAsBuiltinHeader(
   if (!File)
     return false;
 
+  Module::Header H = {Header.FileName, Header.FileName, *File};
   auto Role = headerKindToRole(Header.Kind);
-  Module::Header H = {Header.FileName, std::string(Path.str()), *File};
   addHeader(Mod, H, Role);
   return true;
 }
@@ -417,6 +417,13 @@ bool ModuleMap::isBuiltinHeader(FileEntryRef File) {
          isBuiltinHeaderName(llvm::sys::path::filename(File.getName()));
 }
 
+bool ModuleMap::shouldImportRelativeToBuiltinIncludeDir(StringRef FileName,
+                                                        Module *Module) const {
+  return LangOpts.BuiltinHeadersInSystemModules && BuiltinIncludeDir &&
+         Module->IsSystem && !Module->isPartOfFramework() &&
+         isBuiltinHeaderName(FileName);
+}
+
 ModuleMap::HeadersMap::iterator ModuleMap::findKnownHeader(FileEntryRef File) {
   resolveHeaderDirectives(File);
   HeadersMap::iterator Known = Headers.find(File);