If a switch condition is constant, don't warn about missing enum cases.

If a switch condition is constant, warn if there's no case for it.

Constant switch conditions do come up in reasonable template code.

llvm-svn: 104010

1 files changed, 18 insertions, 1 deletions

diff --git a/clang/test/SemaCXX/switch.cpp b/clang/test/SemaCXX/switch.cpp
index c256960af1d..fc13630bbf1 100644
--- a/clang/test/SemaCXX/switch.cpp
+++ b/clang/test/SemaCXX/switch.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wswitch-enum %s
 
 void test() {
   bool x = true;
@@ -40,3 +40,20 @@ void x3(C &c) {
   switch (c) { // expected-error{{incomplete class type}}
   }
 }
+
+namespace test3 {
+  enum En { A, B, C };
+  template <En how> void foo() {
+    int x = 0, y = 5;
+
+    switch (how) { //expected-warning {{no case matching constant switch condition '2'}}
+    case A: x *= y; break;
+    case B: x += y; break;
+    // No case for C, but it's okay because we have a constant condition.
+    }
+  }
+
+  template void foo<A>();
+  template void foo<B>();
+  template void foo<C>(); //expected-note {{in instantiation}}
+}