Add new check: -check-objc-methodsigs. This check scans methods in

ObjCImplementationDecls and sees if a ancestor class defines a method with the
same selector but with a different type signature. Right now it just compares
return types, and mainly looks at differences in primitive values. The checking
will be expanded in the future.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@53482 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 125 insertions, 0 deletions

diff --git a/lib/Analysis/CheckObjCInstMethSignature.cpp b/lib/Analysis/CheckObjCInstMethSignature.cpp
new file mode 100644
index 0000000000..2572edbc12
--- /dev/null
+++ b/lib/Analysis/CheckObjCInstMethSignature.cpp
@@ -0,0 +1,125 @@
+//=- CheckObjCInstMethodRetTy.cpp - Check ObjC method signatures -*- 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 CheckObjCInstMethSignature, a flow-insenstive check
+//  that determines if an Objective-C class interface incorrectly redefines
+//  the method signature in a subclass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/LocalCheckers.h"
+#include "clang/Analysis/PathDiagnostic.h"
+#include "clang/Analysis/PathSensitive/BugReporter.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/ASTContext.h"
+
+#include "llvm/ADT/DenseMap.h"
+#include <sstream>
+
+using namespace clang;
+
+static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
+                               ASTContext& C) {
+
+  // Right now don't compare the compatibility of pointers.  That involves
+  // looking at subtyping relationships.  FIXME: Future patch.
+  if ((Derived->isPointerType() || Derived->isObjCQualifiedIdType())  && 
+      (Ancestor->isPointerType() || Ancestor->isObjCQualifiedIdType()))
+    return true;
+
+  return C.typesAreCompatible(Derived, Ancestor);
+}
+
+static void CompareReturnTypes(ObjCMethodDecl* MethDerived,
+                               ObjCMethodDecl* MethAncestor,
+                               BugReporter& BR, ASTContext& Ctx,
+                               ObjCImplementationDecl* ID) {
+    
+  QualType ResDerived  = MethDerived->getResultType();
+  QualType ResAncestor = MethAncestor->getResultType(); 
+  
+  if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
+    std::ostringstream os;
+    
+    os << "The Objective-C class '"
+       << MethDerived->getClassInterface()->getName()
+       << "', which is derived from class '"
+       << MethAncestor->getClassInterface()->getName()
+       << "', defines the instance method '"
+       << MethDerived->getSelector().getName()
+       << "' whose return type is '"
+       << ResDerived.getAsString()
+       << "'.  The same method (same selector) is defined in class 'B' and has "
+          "a return type of '"
+       << ResAncestor.getAsString()
+       << "'.  These two types are incompatible, and may result in undefined "
+          "behavior for clients of these classes.";
+    
+    // Refactor.
+    SimpleBugType BT("incompatible instance method return type");
+    DiagCollector C(BT);
+    Diagnostic& Diag = BR.getDiagnostic();    
+    Diag.Report(&C, Ctx.getFullLoc(MethDerived->getLocStart()),
+                Diag.getCustomDiagID(Diagnostic::Warning, os.str().c_str()),
+                NULL, 0, NULL, 0);
+    
+    for (DiagCollector::iterator I = C.begin(), E = C.end(); I != E; ++I)
+      BR.EmitWarning(*I);
+  }
+}
+
+void clang::CheckObjCInstMethSignature(ObjCImplementationDecl* ID,
+                                       BugReporter& BR) {
+  
+  ObjCInterfaceDecl* D = ID->getClassInterface();
+  ObjCInterfaceDecl* C = D->getSuperClass();
+
+  if (!C)
+    return;
+  
+  // Build a DenseMap of the methods for quick querying.
+  typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
+  MapTy IMeths;
+  unsigned NumMethods = 0;
+  
+  for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
+       E=ID->instmeth_end(); I!=E; ++I) {    
+    
+    ObjCMethodDecl* M = *I;
+    IMeths[M->getSelector()] = M;
+    ++NumMethods;
+  }
+
+  // Now recurse the class hierarchy chain looking for methods with the
+  // same signatures.
+  ASTContext& Ctx = BR.getContext();
+  
+  while (C && NumMethods) {
+    for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
+         E=C->instmeth_end(); I!=E; ++I) {
+
+      ObjCMethodDecl* M = *I;
+      Selector S = M->getSelector();
+      
+      MapTy::iterator MI = IMeths.find(S);
+
+      if (MI == IMeths.end() || MI->second == 0)
+        continue;
+      
+      --NumMethods;
+      ObjCMethodDecl* MethDerived = MI->second;
+      MI->second = 0;
+      
+      CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
+    }
+    
+    C = C->getSuperClass();
+  }
+}