[clang-tidy] Make readability-redundant-control-flow not suggest deleting unrelated lines

[localspook]

Closes #171200.

[llvmbot]

@llvm/pr-subscribers-clang-tidy

@llvm/pr-subscribers-clang-tools-extra

Author: Victor Chernyakin (localspook)

Changes

Closes #171200.

---

Full diff: https://github.com/llvm/llvm-project/pull/171287.diff

3 Files Affected:

• (modified) clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp (+5-13)
• (modified) clang-tools-extra/docs/ReleaseNotes.rst (+5)
• (modified) clang-tools-extra/test/clang-tidy/checkers/readability/redundant-control-flow.cpp (+30)

diff --git a/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp b/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
index 132b7ddc4311b..b77108c49f53c 100644
--- a/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
+++ b/clang-tools-extra/clang-tidy/readability/RedundantControlFlowCheck.cpp
@@ -71,19 +71,11 @@ void RedundantControlFlowCheck::issueDiagnostic(
   if (isLocationInMacroExpansion(SM, StmtRange.getBegin()))
     return;
 
-  const CompoundStmt::const_reverse_body_iterator Previous =
-      ++Block->body_rbegin();
-  SourceLocation Start;
-  if (Previous != Block->body_rend())
-    Start = Lexer::findLocationAfterToken(
-        cast<Stmt>(*Previous)->getEndLoc(), tok::semi, SM, getLangOpts(),
-        /*SkipTrailingWhitespaceAndNewLine=*/true);
-  if (!Start.isValid())
-    Start = StmtRange.getBegin();
-  auto RemovedRange = CharSourceRange::getCharRange(
-      Start, Lexer::findLocationAfterToken(
-                 StmtRange.getEnd(), tok::semi, SM, getLangOpts(),
-                 /*SkipTrailingWhitespaceAndNewLine=*/true));
+  const auto RemovedRange = CharSourceRange::getCharRange(
+      StmtRange.getBegin(),
+      Lexer::findLocationAfterToken(StmtRange.getEnd(), tok::semi, SM,
+                                    getLangOpts(),
+                                    /*SkipTrailingWhitespaceAndNewLine=*/true));
 
   diag(StmtRange.getBegin(), Diag) << FixItHint::CreateRemoval(RemovedRange);
 }
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
index d1fb1cba3e45a..9f72f31b3cfa9 100644
--- a/clang-tools-extra/docs/ReleaseNotes.rst
+++ b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -581,6 +581,11 @@ Changes in existing checks
   <clang-tidy/checks/readability/redundant-casting>` check by fixing false
   negatives when explicitly cast from function pointer.
 
+- Improved :doc:`readability-redundant-control-flow
+  <clang-tidy/checks/readability/redundant-control-flow>` by fixing an issue
+  where the check would sometimes suggest deleting not only a redundant
+  ``return`` or ``continue``, but also unrelated lines preceding it.
+
 - Improved :doc:`readability-uppercase-literal-suffix
   <clang-tidy/checks/readability/uppercase-literal-suffix>` check to recognize
   literal suffixes added in C++23 and C23.
diff --git a/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-control-flow.cpp b/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-control-flow.cpp
index 77644902e7772..0083b5e921bc9 100644
--- a/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-control-flow.cpp
+++ b/clang-tools-extra/test/clang-tidy/checkers/readability/redundant-control-flow.cpp
@@ -222,3 +222,33 @@ void call_templates() {
   template_loop(10L);
   template_loop(10U);
 }
+
+void dont_delete_lines_before_return_statement() {
+	do {} while (0);
+#ifdef FOO
+#endif
+  return;
+}
+// CHECK-MESSAGES: :[[@LINE-2]]:3: warning: redundant return statement
+// CHECK-FIXES:      void dont_delete_lines_before_return_statement() {
+// CHECK-FIXES-NEXT: 	 do {} while (0);
+// CHECK-FIXES-NEXT: #ifdef FOO
+// CHECK-FIXES-NEXT: #endif
+// CHECK-FIXES-NEXT: }
+
+void dont_delete_lines_before_continue_statement() {
+  for (;;) {
+	  do {} while (0);
+#ifdef BAR
+#endif
+    continue;
+  }
+}
+// CHECK-MESSAGES: :[[@LINE-3]]:5: warning: redundant continue statement
+// CHECK-FIXES:      void dont_delete_lines_before_continue_statement() {
+// CHECK-FIXES-NEXT:   for (;;) {
+// CHECK-FIXES-NEXT: 	   do {} while (0);
+// CHECK-FIXES-NEXT: #ifdef BAR
+// CHECK-FIXES-NEXT: #endif
+// CHECK-FIXES-NEXT:   }
+// CHECK-FIXES-NEXT: }