clang-1/lib/Analysis/CheckObjCUnusedIVars.cpp

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C++

//==- 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;
return;
}
for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E;++I)
Scan(M, *I);
}
static void Scan(IvarUsageMap& M, ObjCPropertyImplDecl* D) {
if (!D)
return;
ObjCIvarDecl* ID = D->getPropertyIvarDecl();
if (!ID)
return;
IvarUsageMap::iterator I = M.find(ID);
if (I != M.end()) I->second = Used;
}
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.
if (ID->getAccessControl() != ObjCIvarDecl::Private)
continue;
// Skip IB Outlets.
if (ID->getAttr<IBOutletAttr>())
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());
// Scan for @synthesized property methods that act as setters/getters
// to an ivar.
for (ObjCImplementationDecl::propimpl_iterator I = D->propimpl_begin(),
E = D->propimpl_end(); I!=E; ++I)
Scan(M, *I);
// 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 << "Instance variable '" << I->first->getName()
<< "' in class '" << ID->getName()
<< "' is never used by the methods in its @implementation "
"(although it may be used by category methods).";
BR.EmitBasicReport("unused ivar",
os.str().c_str(), I->first->getLocation());
}
}