Don't run -Wunreachable-code on template instantiations. Different instantiations may produce different unreachable code results, and it is very difficult for us to prove that ALL instantiations of a template have specific unreachable code. If we come up with a better solution, then we can revisit this, but this approach will at least greatly reduce the noise of this warning for code that makes use of templates.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145520 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/Sema/AnalysisBasedWarnings.cpp b/lib/Sema/AnalysisBasedWarnings.cpp
index 8b2e269708..54a26b3253 100644
--- a/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/lib/Sema/AnalysisBasedWarnings.cpp
@@ -914,8 +914,14 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
   }
 
   // Warning: check for unreachable code
-  if (P.enableCheckUnreachable)
-    CheckUnreachable(S, AC);
+  if (P.enableCheckUnreachable) {
+    // Only check for unreachable code on non-template instantiations.
+    // Different template instantiations can effectively change the control-flow
+    // and it is very difficult to prove that a snippet of code in a template
+    // is unreachable for all instantiations.
+    if (S.ActiveTemplateInstantiations.empty())
+      CheckUnreachable(S, AC);
+  }
 
   // Check for thread safety violations
   if (P.enableThreadSafetyAnalysis) {