Avoid snowballing errors into additional warnings. To do better, we'd

need an error term for the CFG.  I suspect we'll always have to cope
with getCFG returning 0, though, I'd love to see even that possibility
removed.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@93411 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 948418b42a..40c3e754ad 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1329,11 +1329,14 @@ static void MarkLive(CFGBlock *e, llvm::BitVector &live) {
 
 /// CheckUnreachable - Check for unreachable code.
 void Sema::CheckUnreachable(AnalysisContext &AC) {
+  // We avoid checking when there are errors, as the CFG won't faithfully match
+  // the users code.
+  if (getDiagnostics().hasErrorOccurred())
+    return;
   if (Diags.getDiagnosticLevel(diag::warn_unreachable) == Diagnostic::Ignored)
     return;
 
   CFG *cfg = AC.getCFG();
-  // FIXME: They should never return 0, fix that, delete this code.
   if (cfg == 0)
     return;
   
@@ -1363,7 +1366,6 @@ void Sema::CheckUnreachable(AnalysisContext &AC) {
 /// will return.
 Sema::ControlFlowKind Sema::CheckFallThrough(AnalysisContext &AC) {
   CFG *cfg = AC.getCFG();
-  // FIXME: They should never return 0, fix that, delete this code.
   if (cfg == 0)
     // FIXME: This should be NeverFallThrough
     return NeverFallThroughOrReturn;