Suppress -Wunused-variable for variables declared in headers, which may in

fact be defined and used in another TU.

Reshuffle some test cases because we suppress -Wunused-variable after we've
emitted an error.

This fixes PR15558.

llvm-svn: 179138

1 files changed, 6 insertions, 2 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 6bab9e80cbf..e271f78ed0c 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -751,9 +751,13 @@ void Sema::ActOnEndOfTranslationUnit() {
         if (DiagD->isReferenced()) {
           Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
                 << /*variable*/1 << DiagD->getDeclName();
-        } else {
+        } else if (getSourceManager().isFromMainFile(DiagD->getLocation())) {
+          // If the declaration is in a header which is included into multiple
+          // TUs, it will declare one variable per TU, and one of the other
+          // variables may be used. So, only warn if the declaration is in the
+          // main file.
           Diag(DiagD->getLocation(), diag::warn_unused_variable)
-                << DiagD->getDeclName();
+              << DiagD->getDeclName();
         }
       }
     }