Add prototype implementation of unused ivar check.

llvm-svn: 53942

1 files changed, 87 insertions, 0 deletions

diff --git a/clang/lib/Analysis/CheckObjCUnusedIVars.cpp b/clang/lib/Analysis/CheckObjCUnusedIVars.cpp
new file mode 100644
index 00000000000..4eb273314d5
--- /dev/null
+++ b/clang/lib/Analysis/CheckObjCUnusedIVars.cpp
@@ -0,0 +1,87 @@
+//==- CheckObjCUnusedIVars.cpp - Check for unused ivars ----------*- C++ -*-==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines a CheckObjCUnusedIvars, a checker that
+//  analyzes an Objective-C class's interface/implementation to determine if it
+//  has any ivars that are never accessed.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/LocalCheckers.h"
+#include "clang/Analysis/PathDiagnostic.h"
+#include "clang/Analysis/PathSensitive/BugReporter.h"
+#include "clang/AST/ExprObjC.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/Basic/LangOptions.h"
+#include <sstream>
+
+using namespace clang;
+
+enum IVarState { Unused, Used };
+typedef llvm::DenseMap<ObjCIvarDecl*,IVarState> IvarUsageMap;
+
+static void Scan(IvarUsageMap& M, Stmt* S) {
+  if (!S)
+    return;
+  
+  if (ObjCIvarRefExpr* Ex = dyn_cast<ObjCIvarRefExpr>(S)) {
+    ObjCIvarDecl* D = Ex->getDecl();
+    IvarUsageMap::iterator I = M.find(D);
+    if (I != M.end()) I->second = Used;
+  }
+  else
+    for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E;++I)
+      Scan(M, *I);
+}
+
+void clang::CheckObjCUnusedIvar(ObjCImplementationDecl* D, BugReporter& BR) {
+
+  ObjCInterfaceDecl* ID = D->getClassInterface();
+  IvarUsageMap M;
+
+
+  
+  // Iterate over the ivars.
+  for (ObjCInterfaceDecl::ivar_iterator I=ID->ivar_begin(), E=ID->ivar_end();
+       I!=E; ++I) {
+    
+    ObjCIvarDecl* ID = *I;
+    
+    // Ignore ivars that aren't private.
+    ObjCIvarDecl::AccessControl ac = ID->getAccessControl();
+    if (!(ac == ObjCIvarDecl::None || ac == ObjCIvarDecl::Private))
+      continue;
+    
+    if (ID->getAttr<IBOutletAttr>() == 0)
+      continue;
+    
+    M[ID] = Unused;
+  }
+
+  if (M.empty())
+    return;
+  
+  // Now scan the methods for accesses.
+  for (ObjCImplementationDecl::instmeth_iterator I = D->instmeth_begin(),
+       E = D->instmeth_end(); I!=E; ++I)
+    Scan(M, (*I)->getBody());
+  
+  // Find ivars that are unused.
+  for (IvarUsageMap::iterator I = M.begin(), E = M.end(); I!=E; ++I)
+    if (I->second == Unused) {
+      
+      std::ostringstream os;
+      os << "Private ivar '" << I->first->getName() << "' is never used.";
+      
+      BR.EmitBasicReport("unused ivar",
+                         os.str().c_str(), I->first->getLocation());
+    }
+}
+