Support '-fmodule-file-home-is-cwd' for C++ modules. (#135147)

1 files changed, 36 insertions, 33 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index a48c050..95b5718 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1493,42 +1493,45 @@ void ASTWriter::WriteControlBlock(Preprocessor &PP, StringRef isysroot) {
     unsigned AbbrevCode = Stream.EmitAbbrev(std::move(Abbrev));
     RecordData::value_type Record[] = {MODULE_NAME};
     Stream.EmitRecordWithBlob(AbbrevCode, Record, WritingModule->Name);
-  }
 
-  if (WritingModule && WritingModule->Directory) {
-    SmallString<128> BaseDir;
-    if (PP.getHeaderSearchInfo().getHeaderSearchOpts().ModuleFileHomeIsCwd) {
-      // Use the current working directory as the base path for all inputs.
-      auto CWD = FileMgr.getOptionalDirectoryRef(".");
-      BaseDir.assign(CWD->getName());
-    } else {
-      BaseDir.assign(WritingModule->Directory->getName());
-    }
-    cleanPathForOutput(FileMgr, BaseDir);
-
-    // If the home of the module is the current working directory, then we
-    // want to pick up the cwd of the build process loading the module, not
-    // our cwd, when we load this module.
-    if (!PP.getHeaderSearchInfo().getHeaderSearchOpts().ModuleFileHomeIsCwd &&
-        (!PP.getHeaderSearchInfo()
-              .getHeaderSearchOpts()
-              .ModuleMapFileHomeIsCwd ||
-         WritingModule->Directory->getName() != ".")) {
-      // Module directory.
-      auto Abbrev = std::make_shared<BitCodeAbbrev>();
-      Abbrev->Add(BitCodeAbbrevOp(MODULE_DIRECTORY));
-      Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Directory
-      unsigned AbbrevCode = Stream.EmitAbbrev(std::move(Abbrev));
+    auto BaseDir = [&]() -> std::optional<SmallString<128>> {
+      if (PP.getHeaderSearchInfo().getHeaderSearchOpts().ModuleFileHomeIsCwd) {
+        // Use the current working directory as the base path for all inputs.
+        auto CWD = FileMgr.getOptionalDirectoryRef(".");
+        return CWD->getName();
+      }
+      if (WritingModule->Directory) {
+        return WritingModule->Directory->getName();
+      }
+      return std::nullopt;
+    }();
+    if (BaseDir) {
+      cleanPathForOutput(FileMgr, *BaseDir);
+
+      // If the home of the module is the current working directory, then we
+      // want to pick up the cwd of the build process loading the module, not
+      // our cwd, when we load this module.
+      if (!PP.getHeaderSearchInfo().getHeaderSearchOpts().ModuleFileHomeIsCwd &&
+          (!PP.getHeaderSearchInfo()
+                .getHeaderSearchOpts()
+                .ModuleMapFileHomeIsCwd ||
+           WritingModule->Directory->getName() != ".")) {
+        // Module directory.
+        auto Abbrev = std::make_shared<BitCodeAbbrev>();
+        Abbrev->Add(BitCodeAbbrevOp(MODULE_DIRECTORY));
+        Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Directory
+        unsigned AbbrevCode = Stream.EmitAbbrev(std::move(Abbrev));
+
+        RecordData::value_type Record[] = {MODULE_DIRECTORY};
+        Stream.EmitRecordWithBlob(AbbrevCode, Record, *BaseDir);
+      }
 
-      RecordData::value_type Record[] = {MODULE_DIRECTORY};
-      Stream.EmitRecordWithBlob(AbbrevCode, Record, BaseDir);
+      // Write out all other paths relative to the base directory if possible.
+      BaseDirectory.assign(BaseDir->begin(), BaseDir->end());
+    } else if (!isysroot.empty()) {
+      // Write out paths relative to the sysroot if possible.
+      BaseDirectory = std::string(isysroot);
     }
-
-    // Write out all other paths relative to the base directory if possible.
-    BaseDirectory.assign(BaseDir.begin(), BaseDir.end());
-  } else if (!isysroot.empty()) {
-    // Write out paths relative to the sysroot if possible.
-    BaseDirectory = std::string(isysroot);
   }
 
   // Module map file