From: John McCall <rjmccall@apple.com>
Date: Wed, 31 Mar 2010 02:47:45 +0000 (+0000)
Subject: Support __attribute__((unused)) on types.  This suddenly started firing
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=aec586056d8670c99ba7c4833be13e4eb123cddb;p=clang

Support __attribute__((unused)) on types.  This suddenly started firing
a lot for me on selfhosts, I dunno why.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@99981 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 51514e77a2..b8158bb7a0 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -511,14 +511,30 @@ static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
 
   // Types of valid local variables should be complete, so this should succeed.
   if (const ValueDecl *VD = dyn_cast<ValueDecl>(D)) {
-    if (const RecordType *RT = VD->getType()->getAs<RecordType>()) {
-      if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
+
+    // White-list anything with an __attribute__((unused)) type.
+    QualType Ty = VD->getType();
+
+    // Only look at the outermost level of typedef.
+    if (const TypedefType *TT = dyn_cast<TypedefType>(Ty)) {
+      if (TT->getDecl()->hasAttr<UnusedAttr>())
+        return false;
+    }
+
+    if (const TagType *TT = Ty->getAs<TagType>()) {
+      const TagDecl *Tag = TT->getDecl();
+      if (Tag->hasAttr<UnusedAttr>())
+        return false;
+
+      if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
         if (!RD->hasTrivialConstructor())
           return false;
         if (!RD->hasTrivialDestructor())
           return false;
       }
     }
+
+    // TODO: __attribute__((unused)) templates?
   }
   
   return true;
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index d12dec4561..cc24735c4a 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -524,7 +524,8 @@ static void HandleUnusedAttr(Decl *d, const AttributeList &Attr, Sema &S) {
     return;
   }
 
-  if (!isa<VarDecl>(d) && !isa<ObjCIvarDecl>(d) && !isFunctionOrMethod(d)) {
+  if (!isa<VarDecl>(d) && !isa<ObjCIvarDecl>(d) && !isFunctionOrMethod(d) &&
+      !isa<TypeDecl>(d)) {
     S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
       << Attr.getName() << 2 /*variable and function*/;
     return;
diff --git a/test/Sema/attr-unused.c b/test/Sema/attr-unused.c
index e45ec434f5..28715141b9 100644
--- a/test/Sema/attr-unused.c
+++ b/test/Sema/attr-unused.c
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -verify -fsyntax-only %s
+// RUN: %clang_cc1 -verify -Wunused-variable -fsyntax-only %s
 
 static void (*fp0)(void) __attribute__((unused));
 
@@ -10,3 +10,18 @@ int f1() __attribute__((unused));
 int g0 __attribute__((unused));
 
 int f2() __attribute__((unused(1, 2))); // expected-error {{attribute requires 0 argument(s)}}
+
+struct Test0_unused {} __attribute__((unused));
+struct Test0_not_unused {};
+typedef int Int_unused __attribute__((unused));
+typedef int Int_not_unused;
+
+void test0() {
+  int x; // expected-warning {{unused variable}}
+
+  Int_not_unused i0; // expected-warning {{unused variable}}
+  Int_unused i1;
+
+  struct Test0_not_unused s0; // expected-warning {{unused variable}}
+  struct Test0_unused s1;
+}