[clang-tools-extra] 0ec8120 - [clang-tidy] performance-unnecessary-copy-initialization: Do not remove comments on new lines.

[Felix Berger via cfe-commits]

Author: Felix Berger
Date: 2021-07-12T16:23:04-04:00
New Revision: 0ec812023b43992810499b04222348fdbdb41ef2

URL: https://github.com/llvm/llvm-project/commit/0ec812023b43992810499b04222348fdbdb41ef2
DIFF: https://github.com/llvm/llvm-project/commit/0ec812023b43992810499b04222348fdbdb41ef2.diff

LOG: [clang-tidy] performance-unnecessary-copy-initialization: Do not remove comments on new lines.

When deleting the copy assignment statement because copied variable is not used
only remove trailing comments on the same line.

Differential Revision: https://reviews.llvm.org/D105734

Reviewed-by: ymandel

Added: 
    

Modified: 
    clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
    clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp

Removed: 
    


################################################################################
diff  --git a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
index f69a2079e4ba1..f6b8e44785b5f 100644
--- a/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
+++ b/clang-tools-extra/clang-tidy/performance/UnnecessaryCopyInitialization.cpp
@@ -39,14 +39,35 @@ void recordFixes(const VarDecl &Var, ASTContext &Context,
   }
 }
 
+llvm::Optional<SourceLocation> firstLocAfterNewLine(SourceLocation Loc,
+                                                    SourceManager &SM) {
+  bool Invalid;
+  const char *TextAfter = SM.getCharacterData(Loc, &Invalid);
+  if (Invalid) {
+    return llvm::None;
+  }
+  size_t Offset = std::strcspn(TextAfter, "\n");
+  return Loc.getLocWithOffset(TextAfter[Offset] == '\0' ? Offset : Offset + 1);
+}
+
 void recordRemoval(const DeclStmt &Stmt, ASTContext &Context,
                    DiagnosticBuilder &Diagnostic) {
-  // Attempt to remove the whole line until the next non-comment token.
-  auto Tok = utils::lexer::findNextTokenSkippingComments(
-      Stmt.getEndLoc(), Context.getSourceManager(), Context.getLangOpts());
-  if (Tok) {
-    Diagnostic << FixItHint::CreateRemoval(SourceRange(
-        Stmt.getBeginLoc(), Tok->getLocation().getLocWithOffset(-1)));
+  auto &SM = Context.getSourceManager();
+  // Attempt to remove trailing comments as well.
+  auto Tok = utils::lexer::findNextTokenSkippingComments(Stmt.getEndLoc(), SM,
+                                                         Context.getLangOpts());
+  llvm::Optional<SourceLocation> PastNewLine =
+      firstLocAfterNewLine(Stmt.getEndLoc(), SM);
+  if (Tok && PastNewLine) {
+    auto BeforeFirstTokenAfterComment = Tok->getLocation().getLocWithOffset(-1);
+    // Remove until the end of the line or the end of a trailing comment which
+    // ever comes first.
+    auto End =
+        SM.isBeforeInTranslationUnit(*PastNewLine, BeforeFirstTokenAfterComment)
+            ? *PastNewLine
+            : BeforeFirstTokenAfterComment;
+    Diagnostic << FixItHint::CreateRemoval(
+        SourceRange(Stmt.getBeginLoc(), End));
   } else {
     Diagnostic << FixItHint::CreateRemoval(Stmt.getSourceRange());
   }

diff  --git a/clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp b/clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
index b66a88e5cf81f..3ce151035d5be 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/performance-unnecessary-copy-initialization.cpp
@@ -596,8 +596,15 @@ void positiveUnusedReferenceIsRemoved() {
   // CHECK-FIXES: int i = 0; // Foo bar.
   auto TrailingCommentRemoved = ExpensiveTypeReference(); // Trailing comment.
   // CHECK-MESSAGES: [[@LINE-1]]:8: warning: the variable 'TrailingCommentRemoved' is copy-constructed from a const reference but is never used;
-  // CHECK-FIXES-NOT: auto TrailingCommentRemoved = ExpensiveTypeReference(); // Trailing comment.
+  // CHECK-FIXES-NOT: auto TrailingCommentRemoved = ExpensiveTypeReference();
+  // CHECK-FIXES-NOT: // Trailing comment.
   // clang-format on
+
+  auto UnusedAndUnnecessary = ExpensiveTypeReference();
+  // Comments on a new line should not be deleted.
+  // CHECK-MESSAGES: [[@LINE-2]]:8: warning: the variable 'UnusedAndUnnecessary' is copy-constructed
+  // CHECK-FIXES-NOT: auto UnusedAndUnnecessary = ExpensiveTypeReference();
+  // CHECK-FIXES: // Comments on a new line should not be deleted.
 }
 
 void negativeloopedOverObjectIsModified() {