Warn when jumping out of a __finally block via continue, break, return, __leave.

Since continue, break, return are much more common than __finally, this tries
to keep the work for continue, break, return O(1).  Sema keeps a stack of active
__finally scopes (to do this, ActOnSEHFinally() is split into
ActOnStartSEHFinally() and ActOnFinishSEHFinally()), and the various jump
statements then check if the current __finally scope (if present) is deeper
than then destination scope of the jump.

The same warning for goto statements is still missing.

This is the moral equivalent of MSVC's C4532.

llvm-svn: 231623

1 files changed, 20 insertions, 4 deletions

diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index aaf29db702c..11ec4f5321e 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -2428,6 +2428,14 @@ Sema::ActOnIndirectGotoStmt(SourceLocation GotoLoc, SourceLocation StarLoc,
   return new (Context) IndirectGotoStmt(GotoLoc, StarLoc, E);
 }
 
+static void CheckJumpOutOfSEHFinally(Sema &S, SourceLocation Loc,
+                                     const Scope &DestScope) {
+  if (!S.CurrentSEHFinally.empty() &&
+      DestScope.Contains(*S.CurrentSEHFinally.back())) {
+    S.Diag(Loc, diag::warn_jump_out_of_seh_finally);
+  }
+}
+
 StmtResult
 Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
   Scope *S = CurScope->getContinueParent();
@@ -2435,6 +2443,7 @@ Sema::ActOnContinueStmt(SourceLocation ContinueLoc, Scope *CurScope) {
     // C99 6.8.6.2p1: A break shall appear only in or as a loop body.
     return StmtError(Diag(ContinueLoc, diag::err_continue_not_in_loop));
   }
+  CheckJumpOutOfSEHFinally(*this, ContinueLoc, *S);
 
   return new (Context) ContinueStmt(ContinueLoc);
 }
@@ -2449,6 +2458,7 @@ Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
   if (S->isOpenMPLoopScope())
     return StmtError(Diag(BreakLoc, diag::err_omp_loop_cannot_use_stmt)
                      << "break");
+  CheckJumpOutOfSEHFinally(*this, BreakLoc, *S);
 
   return new (Context) BreakStmt(BreakLoc);
 }
@@ -2908,6 +2918,8 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
     CurScope->setNoNRVO();
   }
 
+  CheckJumpOutOfSEHFinally(*this, ReturnLoc, *CurScope->getFnParent());
+
   return R;
 }
 
@@ -3406,11 +3418,14 @@ Sema::ActOnSEHExceptBlock(SourceLocation Loc,
   return SEHExceptStmt::Create(Context,Loc,FilterExpr,Block);
 }
 
-StmtResult
-Sema::ActOnSEHFinallyBlock(SourceLocation Loc,
-                           Stmt *Block) {
+void Sema::ActOnStartSEHFinallyBlock() {
+  CurrentSEHFinally.push_back(CurScope);
+}
+
+StmtResult Sema::ActOnFinishSEHFinallyBlock(SourceLocation Loc, Stmt *Block) {
   assert(Block);
-  return SEHFinallyStmt::Create(Context,Loc,Block);
+  CurrentSEHFinally.pop_back();
+  return SEHFinallyStmt::Create(Context, Loc, Block);
 }
 
 StmtResult
@@ -3420,6 +3435,7 @@ Sema::ActOnSEHLeaveStmt(SourceLocation Loc, Scope *CurScope) {
     SEHTryParent = SEHTryParent->getParent();
   if (!SEHTryParent)
     return StmtError(Diag(Loc, diag::err_ms___leave_not_in___try));
+  CheckJumpOutOfSEHFinally(*this, Loc, *SEHTryParent);
 
   return new (Context) SEHLeaveStmt(Loc);
 }