Implemented one of the checks requested in PR 2600:

"Method accepting NSError** argument should have non-void return value to indicate that an error occurred."

Test case written, but the header needs to be delta-debugged reduced.  Will commit shortly.

llvm-svn: 56297

clang/Driver/Analyses.def

@@ -34,6 +34,10 @@ ANALYSIS(WarnObjCDealloc, "warn-objc-missing-dealloc",
  "Warn about Objective-C classes that lack a correct implementation of -dealloc",
  ObjCImplementation)
  
+ANALYSIS(WarnObjCNSError, "warn-objc-nserror-methods",
+  "Check coding rules for 'Creating and Returning NSError Objects'",
+  ObjCImplementation)
+ 
 ANALYSIS(WarnObjCUnusedIvars, "warn-objc-unused-ivars",
   "Warn about private ivars that are never used", ObjCImplementation)
 

clang/Driver/AnalysisConsumer.cpp

@@ -431,6 +431,11 @@ static void ActionWarnObjCMethSigs(AnalysisManager& mgr) {
                              BR);
 }
 
+static void ActionWarnObjCNSError(AnalysisManager& mgr) {
+  BugReporter BR(mgr);
+  CheckNSError(cast<ObjCImplementationDecl>(mgr.getCodeDecl()), BR);
+}
+
 //===----------------------------------------------------------------------===//
 // AnalysisConsumer creation.
 //===----------------------------------------------------------------------===//

clang/include/clang/Analysis/LocalCheckers.h

@@ -46,6 +46,7 @@ void CheckObjCDealloc(ObjCImplementationDecl* D, const LangOptions& L,
   
 void CheckObjCInstMethSignature(ObjCImplementationDecl* ID, BugReporter& BR);
 void CheckObjCUnusedIvar(ObjCImplementationDecl* D, BugReporter& BR);
+void CheckNSError(ObjCImplementationDecl* D, BugReporter& BR);
   
 void RegisterAppleChecks(GRExprEngine& Eng);
   

clang/lib/Analysis/CheckNSError.cpp

@@ -0,0 +1,72 @@
+//=- CheckNSError.cpp - Coding conventions for uses of NSError ---*- 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 CheckNSError, a flow-insenstive check
+//  that determines if an Objective-C class interface correctly returns
+//  a non-void return type.
+//
+//  File under feature request PR 2600.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Analysis/LocalCheckers.h"
+#include "clang/Analysis/PathSensitive/BugReporter.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/ASTContext.h"
+
+using namespace clang;
+
+void clang::CheckNSError(ObjCImplementationDecl* ID, BugReporter& BR) {
+  // Look at the @interface for this class.
+  ObjCInterfaceDecl* D = ID->getClassInterface();
+  
+  // Get the ASTContext.  Useful for querying type information.
+  ASTContext &Ctx = BR.getContext();
+  
+  // Get the IdentifierInfo* for "NSError".
+  IdentifierInfo* NSErrorII = &Ctx.Idents.get("NSError");
+
+  // Scan the methods.  See if any of them have an argument of type NSError**.  
+  for (ObjCInterfaceDecl::instmeth_iterator I=D->instmeth_begin(),
+        E=D->instmeth_end(); I!=E; ++I) {
+
+    // Get the method declaration.
+    ObjCMethodDecl* M = *I;
+    
+    // Check for a non-void return type.
+    if (M->getResultType() != Ctx.VoidTy)
+      continue;
+
+    for (ObjCMethodDecl::param_iterator PI=M->param_begin(), 
+         PE=M->param_end(); PI!=PE; ++PI) {
+      
+      const PointerType* PPT = (*PI)->getType()->getAsPointerType();
+      if (!PPT) continue;
+      
+      const PointerType* PT = PPT->getPointeeType()->getAsPointerType();
+      if (!PT) continue;
+      
+      const ObjCInterfaceType *IT =
+        PT->getPointeeType()->getAsObjCInterfaceType();
+      
+      if (!IT) continue;
+      
+      // Check if IT is "NSError".
+      if (IT->getDecl()->getIdentifier() == NSErrorII) {
+        // Documentation: "Creating and Returning NSError Objects"
+        BR.EmitBasicReport("Bad return type when passing NSError**",
+         "Method accepting NSError** argument should have "
+         "non-void return value to indicate that an error occurred.",
+         M->getLocStart());
+        break;
+      }
+    }
+  }
+}