From 5d068499a7b43a5c9a4375f7a4cdbfc238e0b683 Mon Sep 17 00:00:00 2001
From: Ted Kremenek <kremenek@apple.com>
Date: Wed, 26 Jan 2011 04:49:52 +0000
Subject: [PATCH] Teach -Wreturn-type that destructors can appear after a
 'return' in a CFGBlock.  This accidentally was working before, but the false
 assumption that 'return' always appeared at the end of the block was
 uncovered by a recent change.

llvm-svn: 124280
---
 clang/lib/Sema/AnalysisBasedWarnings.cpp     | 25 +++++++++++---------
 clang/test/SemaCXX/warn-missing-noreturn.cpp | 10 ++++++++
 2 files changed, 24 insertions(+), 11 deletions(-)

diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index 2f02e158cbd7..99f19fca7847 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -121,26 +121,29 @@ static ControlFlowKind CheckFallThrough(AnalysisContext &AC) {
     const CFGBlock& B = **I;
     if (!live[B.getBlockID()])
       continue;
-    if (B.size() == 0) {
+
+    // Destructors can appear after the 'return' in the CFG.  This is
+    // normal.  We need to look pass the destructors for the return
+    // statement (if it exists).
+    CFGBlock::const_reverse_iterator ri = B.rbegin(), re = B.rend();
+    for ( ; ri != re ; ++ri) {
+      CFGElement CE = *ri;
+      if (isa<CFGStmt>(CE))
+        break;
+    }
+    
+    // No more CFGElements in the block?
+    if (ri == re) {
       if (B.getTerminator() && isa<CXXTryStmt>(B.getTerminator())) {
         HasAbnormalEdge = true;
         continue;
       }
-
       // A labeled empty statement, or the entry block...
       HasPlainEdge = true;
       continue;
     }
-    CFGElement CE = B[B.size()-1];
-    
-    if (!isa<CFGStmt>(CE)) {
-      HasPlainEdge = true;
-      continue;
-    }
 
-    CFGStmt CS = CE.getAs<CFGStmt>();
-    if (!CS.isValid())
-      continue;
+    CFGStmt CS = cast<CFGStmt>(*ri);
     Stmt *S = CS.getStmt();
     if (isa<ReturnStmt>(S)) {
       HasLiveReturn = true;
diff --git a/clang/test/SemaCXX/warn-missing-noreturn.cpp b/clang/test/SemaCXX/warn-missing-noreturn.cpp
index 08a20b627c54..4caff66af703 100644
--- a/clang/test/SemaCXX/warn-missing-noreturn.cpp
+++ b/clang/test/SemaCXX/warn-missing-noreturn.cpp
@@ -93,3 +93,13 @@ int rdar8875247_test() {
   rdar8875247 f;
 } // expected-warning{{control reaches end of non-void function}}
 
+struct rdar8875247_B {
+  rdar8875247_B();
+  ~rdar8875247_B();
+};
+
+rdar8875247_B test_rdar8875247_B() {
+  rdar8875247_B f;
+  return f;
+} // no-warning
+