[clang][Frontend] Use move semantics when translating standalone diagnostics (NFC)

[naveen-seth]

This optimizes translateStandaloneDiag to avoid copying strings in multiple places and cleans up a hard-to-read transform.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Naveen Seth Hanig (naveen-seth)

Changes

This optimizes translateStandaloneDiag to avoid copying strings in multiple places and cleans up a hard-to-read transform.

---

Full diff: https://github.com/llvm/llvm-project/pull/172746.diff

3 Files Affected:

• (modified) clang/include/clang/Frontend/StandaloneDiagnostic.h (+1-1)
• (modified) clang/lib/Frontend/ASTUnit.cpp (+5-7)
• (modified) clang/lib/Frontend/StandaloneDiagnostic.cpp (+6-6)

diff --git a/clang/include/clang/Frontend/StandaloneDiagnostic.h b/clang/include/clang/Frontend/StandaloneDiagnostic.h
index c23d5f95e0c2f..d92d58c218c71 100644
--- a/clang/include/clang/Frontend/StandaloneDiagnostic.h
+++ b/clang/include/clang/Frontend/StandaloneDiagnostic.h
@@ -74,7 +74,7 @@ struct StandaloneDiagnostic {
 /// StandaloneDiagnostics themselfs cannot be emitted directly.
 StoredDiagnostic
 translateStandaloneDiag(FileManager &FileMgr, SourceManager &SrcMgr,
-                        const StandaloneDiagnostic &StandaloneDiag,
+                        StandaloneDiagnostic StandaloneDiag,
                         llvm::StringMap<SourceLocation> &SrcLocCache);
 
 } // namespace clang
diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index e72317da64596..89c4a9edc1051 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -1225,13 +1225,11 @@ bool ASTUnit::Parse(std::shared_ptr<PCHContainerOperations> PCHContainerOps,
   if (SavedMainFileBuffer) {
     StoredDiagnostics.clear();
     StoredDiagnostics.reserve(PreambleDiagnostics.size());
-    llvm::transform(std::move(PreambleDiagnostics),
-                    std::back_inserter(StoredDiagnostics),
-                    [&](auto &&StandaloneDiag) {
-                      return translateStandaloneDiag(
-                          getFileManager(), getSourceManager(),
-                          std::move(StandaloneDiag), PreambleSrcLocCache);
-                    });
+    for (auto &PreambleDiag : PreambleDiagnostics) {
+      StoredDiagnostics.push_back(translateStandaloneDiag(
+          getFileManager(), getSourceManager(), std::move(PreambleDiag),
+          PreambleSrcLocCache));
+    }
   } else
     PreambleSrcLocCache.clear();
 
diff --git a/clang/lib/Frontend/StandaloneDiagnostic.cpp b/clang/lib/Frontend/StandaloneDiagnostic.cpp
index 4f19c91b7d266..d5776a5377bcf 100644
--- a/clang/lib/Frontend/StandaloneDiagnostic.cpp
+++ b/clang/lib/Frontend/StandaloneDiagnostic.cpp
@@ -55,7 +55,7 @@ StandaloneDiagnostic::StandaloneDiagnostic(const LangOptions &LangOpts,
 
 StoredDiagnostic
 translateStandaloneDiag(FileManager &FileMgr, SourceManager &SrcMgr,
-                        const StandaloneDiagnostic &StandaloneDiag,
+                        StandaloneDiagnostic StandaloneDiag,
                         llvm::StringMap<SourceLocation> &SrcLocCache) {
   const auto FileRef = FileMgr.getOptionalFileRef(StandaloneDiag.Filename);
   if (!FileRef)
@@ -77,7 +77,7 @@ translateStandaloneDiag(FileManager &FileMgr, SourceManager &SrcMgr,
 
     if (FileLoc.isInvalid())
       return StoredDiagnostic(StandaloneDiag.Level, StandaloneDiag.ID,
-                              StandaloneDiag.Message);
+                              std::move(StandaloneDiag.Message));
 
     SrcLocCache[StandaloneDiag.Filename] = FileLoc;
   }
@@ -100,9 +100,9 @@ translateStandaloneDiag(FileManager &FileMgr, SourceManager &SrcMgr,
 
   SmallVector<FixItHint, 2> TranslatedFixIts;
   TranslatedFixIts.reserve(StandaloneDiag.FixIts.size());
-  for (const auto &FixIt : StandaloneDiag.FixIts) {
+  for (auto &FixIt : StandaloneDiag.FixIts) {
     FixItHint TranslatedFixIt;
-    TranslatedFixIt.CodeToInsert = FixIt.CodeToInsert;
+    TranslatedFixIt.CodeToInsert = std::move(FixIt.CodeToInsert);
     TranslatedFixIt.RemoveRange = ConvertOffsetRange(FixIt.RemoveRange);
     TranslatedFixIt.InsertFromRange = ConvertOffsetRange(FixIt.InsertFromRange);
     TranslatedFixIt.BeforePreviousInsertions = FixIt.BeforePreviousInsertions;
@@ -110,8 +110,8 @@ translateStandaloneDiag(FileManager &FileMgr, SourceManager &SrcMgr,
   }
 
   return StoredDiagnostic(StandaloneDiag.Level, StandaloneDiag.ID,
-                          StandaloneDiag.Message, Loc, TranslatedRanges,
-                          TranslatedFixIts);
+                          std::move(StandaloneDiag.Message), Loc,
+                          TranslatedRanges, TranslatedFixIts);
 }
 
 } // namespace clang

[naveen-seth]

For additional context:

PR #152770 (WIP) previously used a separate, slightly different implementation of StandaloneDiagnostic and related code from the one in ASTUnit.

After PR #169599 resolved the linkage issues and extracted StandaloneDiagnostic from the ASTUnit implementation, the implementation could be shared.

This change applies the optimizations from PR #152770’s translateStandaloneDiag implementation to the now-shared implementation.