Enhance the unused ivar checker to not consider an ivar to be accidentally unused

when it is explicitly marked as unused via __attribute__((unused)).

llvm-svn: 97104

clang/lib/Checker/CMakeLists.txt

@@ -18,7 +18,6 @@ add_clang_library(clangChecker
   CheckDeadStores.cpp
   CheckObjCDealloc.cpp
   CheckObjCInstMethSignature.cpp
-  CheckObjCUnusedIVars.cpp
   CheckSecuritySyntaxOnly.cpp
   CheckSizeofPointer.cpp
   Checker.cpp
@@ -42,6 +41,7 @@ add_clang_library(clangChecker
   NSErrorChecker.cpp
   NoReturnFunctionChecker.cpp
   OSAtomicChecker.cpp
+  ObjCUnusedIVarsChecker.cpp
   PathDiagnostic.cpp
   PointerArithChecker.cpp
   PointerSubChecker.cpp

clang/lib/Checker/ObjCUnusedIVarsChecker.cpp

@@ -1,4 +1,4 @@
-//==- CheckObjCUnusedIVars.cpp - Check for unused ivars ----------*- C++ -*-==//
+//==- ObjCUnusedIVarsChecker.cpp - Check for unused ivars --------*- C++ -*-==//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -109,12 +109,12 @@ void clang::CheckObjCUnusedIvar(const ObjCImplementationDecl *D,
 
     const ObjCIvarDecl* ID = *I;
 
-    // Ignore ivars that aren't private.
-    if (ID->getAccessControl() != ObjCIvarDecl::Private)
-      continue;
-
-    // Skip IB Outlets.
-    if (ID->getAttr<IBOutletAttr>())
+    // Ignore ivars that...
+    // (a) aren't private
+    // (b) explicitly marked unused
+    // (c) are iboutlets
+    if (ID->getAccessControl() != ObjCIvarDecl::Private ||
+        ID->getAttr<UnusedAttr>() || ID->getAttr<IBOutletAttr>())
       continue;
 
     M[ID] = Unused;
@@ -126,7 +126,6 @@ void clang::CheckObjCUnusedIvar(const ObjCImplementationDecl *D,
   // Now scan the implementation declaration.
   Scan(M, D);
 
-  
   // Any potentially unused ivars?
   bool hasUnused = false;
   for (IvarUsageMap::iterator I = M.begin(), E = M.end(); I!=E; ++I)

clang/test/Analysis/unused-ivars.m

@@ -81,3 +81,18 @@ int radar_7254495(RDar7254495 *a) {
   return a->x;
 }
 @end
+
+//===----------------------------------------------------------------------===//
+// <rdar://problem/7353683> - consult attribute((unused)) to silence warnings
+// about unused instance variables
+//===----------------------------------------------------------------------===//
+
+@interface RDar7353683 {
+@private
+  id x __attribute__((unused));
+}
+@end
+
+@implementation RDar7353683
+@end
+