Improve our handling of the -Wunused-variable warning in templates. In

particular, don't complain about unused variables that have dependent
type until instantiation time, so that we can look at the type of the
variable. Moreover, only complain about unused variables that have
neither a user-declared constructor nor a non-trivial destructor.

llvm-svn: 103362

1 files changed, 6 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index a32c0e1ac32..d3d6c2209f5 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -351,7 +351,8 @@ Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
     Var->setLexicalDeclContext(D->getLexicalDeclContext());
 
   Var->setAccess(D->getAccess());
-
+  Var->setUsed(D->isUsed());
+  
   // FIXME: In theory, we could have a previous declaration for variables that
   // are not static data members.
   bool Redeclaration = false;
@@ -419,6 +420,10 @@ Decl *TemplateDeclInstantiator::VisitVarDecl(VarDecl *D) {
   } else if (!Var->isStaticDataMember() || Var->isOutOfLine())
     SemaRef.ActOnUninitializedDecl(Sema::DeclPtrTy::make(Var), false);
 
+  // Diagnose unused local variables.
+  if (!Var->isInvalidDecl() && Owner->isFunctionOrMethod() && !Var->isUsed())
+    SemaRef.DiagnoseUnusedDecl(Var);
+  
   return Var;
 }