Sema: do not warn about unused const vars if main file is a header

If we pass a header to libclang, e.g. because it's open in an editor in
an IDE, warnings about unused const vars are not useful: other files
that include the header might use those constants. So when -x *-header
is passed as command-line option, suppress this warning.

llvm-svn: 285386

1 files changed, 5 insertions, 2 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 2a3be84263c..c2622ecab4b 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -865,8 +865,11 @@ void Sema::ActOnEndOfTranslationUnit() {
           Diag(DiagD->getLocation(), diag::warn_unneeded_internal_decl)
                 << /*variable*/1 << DiagD->getDeclName();
         } else if (DiagD->getType().isConstQualified()) {
-          Diag(DiagD->getLocation(), diag::warn_unused_const_variable)
-              << DiagD->getDeclName();
+          const SourceManager &SM = SourceMgr;
+          if (SM.getMainFileID() != SM.getFileID(DiagD->getLocation()) ||
+              !PP.getLangOpts().IsHeaderFile)
+            Diag(DiagD->getLocation(), diag::warn_unused_const_variable)
+                << DiagD->getDeclName();
         } else {
           Diag(DiagD->getLocation(), diag::warn_unused_variable)
               << DiagD->getDeclName();