Suppress warning on unreachable [[clang::fallthrough]] within a template instantiation.

We don't know whether some other instantiation of the template might be able to
reach the annotation, so warning on it has a high chance of false positives.

Patch by Ahmed Asadi!

Differential Revision: https://reviews.llvm.org/D31069


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@298477 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 0 deletions

diff --git a/test/SemaCXX/P30636.cpp b/test/SemaCXX/P30636.cpp
new file mode 100644
index 0000000000..2e2affb0cf
--- /dev/null
+++ b/test/SemaCXX/P30636.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wimplicit-fallthrough %s
+// expected-no-diagnostics
+
+template<bool param>
+int fallthrough_template(int i)
+{
+  switch (i) {
+    case 1:
+      if (param)
+        return 3;
+      [[clang::fallthrough]]; // no warning here, for an unreachable annotation (in the fallthrough_template<true> case) in a template function
+    case 2:
+      return 4;
+    default:
+      return 5;
+  }
+}
+                                      
+template int fallthrough_template<true>(int);
+