From: Alexander Kornienko <alexfh@google.com>
Date: Fri, 25 Jan 2013 15:49:34 +0000 (+0000)
Subject: Don't suggest to insert [[clang::fallthrough]] before empty cases. Fix for multiple... 
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e992ed1a065d857947b3969e6b779c41cc35c234;p=clang

Don't suggest to insert [[clang::fallthrough]] before empty cases. Fix for multiple case labels.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173458 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index d5fa959bf4..78864ec285 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -846,13 +846,13 @@ static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
   int AnnotatedCnt;
 
   for (CFG::reverse_iterator I = Cfg->rbegin(), E = Cfg->rend(); I != E; ++I) {
-    const CFGBlock &B = **I;
-    const Stmt *Label = B.getLabel();
+    const CFGBlock *B = *I;
+    const Stmt *Label = B->getLabel();
 
     if (!Label || !isa<SwitchCase>(Label))
       continue;
 
-    if (!FM.checkFallThroughIntoBlock(B, AnnotatedCnt))
+    if (!FM.checkFallThroughIntoBlock(*B, AnnotatedCnt))
       continue;
 
     S.Diag(Label->getLocStart(),
@@ -864,8 +864,13 @@ static void DiagnoseSwitchLabelsFallthrough(Sema &S, AnalysisDeclContext &AC,
       if (L.isMacroID())
         continue;
       if (S.getLangOpts().CPlusPlus11) {
-        const Stmt *Term = B.getTerminator();
-        if (!(B.empty() && Term && isa<BreakStmt>(Term))) {
+        const Stmt *Term = B->getTerminator();
+        // Skip empty cases.
+        while (B->empty() && !Term && B->succ_size() == 1) {
+          B = *B->succ_begin();
+          Term = B->getTerminator();
+        }
+        if (!(B->empty() && Term && isa<BreakStmt>(Term))) {
           Preprocessor &PP = S.getPreprocessor();
           TokenValue Tokens[] = {
             tok::l_square, tok::l_square, PP.getIdentifierInfo("clang"),
diff --git a/test/SemaCXX/switch-implicit-fallthrough.cpp b/test/SemaCXX/switch-implicit-fallthrough.cpp
index cfc29c237c..75dda8a961 100644
--- a/test/SemaCXX/switch-implicit-fallthrough.cpp
+++ b/test/SemaCXX/switch-implicit-fallthrough.cpp
@@ -34,6 +34,8 @@ int fallthrough(int n) {
     case 6:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert '[[clang::fallthrough]];' to silence this warning}} expected-note{{insert 'break;' to avoid fall-through}}
       n += 300;
     case 66:  // expected-warning{{unannotated fall-through between switch labels}} expected-note{{insert 'break;' to avoid fall-through}}
+    case 67:
+    case 68:
       break;
   }
   switch (n / 20) {