Warn if function or variable cannot be implicitly instantiated

With this patch compiler emits warning if it tries to make implicit instantiation
of a template but cannot find the template definition. The warning can be suppressed
by explicit instantiation declaration or by command line options
-Wundefined-var-template and -Wundefined-func-template. The implementation follows
the discussion of http://reviews.llvm.org/D12326.

Differential Revision: http://reviews.llvm.org/D16396

llvm-svn: 266719

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/undefined-internal.cpp b/clang/test/SemaCXX/undefined-internal.cpp
index 29ca5de6d41..59e6fdf9af0 100644
--- a/clang/test/SemaCXX/undefined-internal.cpp
+++ b/clang/test/SemaCXX/undefined-internal.cpp
@@ -82,6 +82,7 @@ namespace test5 {
     static int var; // expected-warning {{variable 'test5::B<test5::(anonymous namespace)::A>::var' has internal linkage but is not defined}}
     static void foo(); // expected-warning {{function 'test5::B<test5::(anonymous namespace)::A>::foo' has internal linkage but is not defined}}
   };
+  extern template int B<A>::var;
 
   void test() {
     B<A>::var = 0; // expected-note {{used here}}