[PATCH] D158480: [clang-tidy][readability-braces-around-statements] ignore false-positive for constexpr if statement in lambda expression

[Congcong Cai via Phabricator via cfe-commits]

HerrCai0907 created this revision.
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Fixed: #64545

When TreeTransform, Stmt in constexpr IfStmt will be transform to NullStmt.
This NullStmt has the different beginning token.
This patch add addtional check in checkStmt to handle this case.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D158480

Files:
  clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
  clang-tools-extra/docs/ReleaseNotes.rst
  clang-tools-extra/test/clang-tidy/checkers/readability/braces-around-statements.cpp


Index: clang-tools-extra/test/clang-tidy/checkers/readability/braces-around-statements.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/readability/braces-around-statements.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/readability/braces-around-statements.cpp
@@ -457,3 +457,25 @@
   // CHECK-FIXES-NEXT: }
 
 }
+
+template <bool A>
+auto constexpr_lambda_1 = [] {
+  if constexpr (A) {
+    1;
+  }
+};
+
+template <bool A>
+auto constexpr_lambda_2 = [] {
+  // CHECK-MESSAGES: :[[@LINE+1]]:19: warning: statement should be inside braces
+  if constexpr (A)
+    1;
+  // CHECK-FIXES:if constexpr (A) {
+  // CHECK-FIXES-NEXT:1;
+  // CHECK-FIXES-NEXT:}
+};
+
+void test_constexpr() {
+  constexpr_lambda_1<false>();
+  constexpr_lambda_2<false>();
+}
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -228,6 +228,10 @@
   <clang-tidy/checks/performance/noexcept-swap>` check to enforce a stricter
   match with the swap function signature, eliminating false-positives.
 
+- Improved :doc:`readability-braces-around-statements
+  <clang-tidy/checks/readability/braces-around-statements>` check to
+  ignore false-positive for constexpr if statement in lambda expression.
+
 - Improved :doc:`readability-container-size-empty
   <clang-tidy/checks/readability/container-size-empty>` check to
   detect comparison between string and empty string literals.
Index: clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
+++ clang-tools-extra/clang-tidy/readability/BracesAroundStatementsCheck.cpp
@@ -192,6 +192,9 @@
   while (const auto *AS = dyn_cast<AttributedStmt>(S))
     S = AS->getSubStmt();
 
+  const SourceManager &SM = *Result.SourceManager;
+  const ASTContext *Context = Result.Context;
+
   // 1) If there's a corresponding "else" or "while", the check inserts "} "
   // right before that token.
   // 2) If there's a multi-line block comment starting on the same line after
@@ -204,10 +207,15 @@
     return false;
   }
 
+  // When TreeTransform, Stmt in constexpr IfStmt will be transform to NullStmt.
+  // This NullStmt can be detected according to beginning token.
+  const SourceLocation StmtBeginLoc = S->getBeginLoc();
+  if (isa<NullStmt>(S) && StmtBeginLoc.isValid() &&
+      getTokenKind(StmtBeginLoc, SM, Context) == tok::l_brace)
+    return false;
+
   if (!InitialLoc.isValid())
     return false;
-  const SourceManager &SM = *Result.SourceManager;
-  const ASTContext *Context = Result.Context;
 
   // Convert InitialLoc to file location, if it's on the same macro expansion
   // level as the start of the statement. We also need file locations for


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