[arcmt] More automatic transformations and safety improvements; rdar://9615812 :

- Replace calling -zone with 'nil'. -zone is obsolete in ARC.
- Allow removing retain/release on a static global var.
- Fix assertion hit when scanning for name references outside a NSAutoreleasePool scope.
- Automatically add bridged casts for results of objc method calls and when calling CFRetain, for example:

NSString *s;
CFStringRef ref = [s string];   -> CFStringRef ref = (__bridge CFStringRef)([s string]);
ref = s.string;                 -> ref = (__bridge CFStringRef)(s.string);
ref = [NSString new];           -> ref = (__bridge_retained CFStringRef)([NSString new]);
ref = [s newString];            -> ref = (__bridge_retained CFStringRef)([s newString]);
ref = [[NSString alloc] init];  -> ref = (__bridge_retained CFStringRef)([[NSString alloc] init]);
ref = [[s string] retain];      -> ref = (__bridge_retained CFStringRef)([s string]);
ref = CFRetain(s);              -> ref = (__bridge_retained CFTypeRef)(s);
ref = [s retain];               -> ref = (__bridge_retained CFStringRef)(s);

- Emit migrator error when trying to cast to CF type the result of autorelease/release:
  for

CFStringRef f3() {
  return (CFStringRef)[[[NSString alloc] init] autorelease];
}

emits:

t.m:12:10: error: [rewriter] it is not safe to cast to 'CFStringRef' the result of 'autorelease' message; a __bridge cast may result in a pointer to a destroyed object and a __bridge_retained may leak the object
  return (CFStringRef)[[[NSString alloc] init] autorelease];
         ^            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
t.m:12:3: note: [rewriter] remove the cast and change return type of function to 'NSString *' to have the object automatically autoreleased
  return (CFStringRef)[[[NSString alloc] init] autorelease];
  ^

- Before changing attributes to weak/unsafe_unretained, check if the backing ivar
  is set to a +1 object, in which case use 'strong' instead.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136208 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 1 deletions

diff --git a/lib/ARCMigrate/TransAPIUses.cpp b/lib/ARCMigrate/TransAPIUses.cpp
index 228ca3e091..781ad7742d 100644
--- a/lib/ARCMigrate/TransAPIUses.cpp
+++ b/lib/ARCMigrate/TransAPIUses.cpp
@@ -9,17 +9,19 @@
 //
 // checkAPIUses:
 //
-// Emits error with some API uses that are not safe in ARC mode:
+// Emits error/fix with some API uses that are obsolete or not safe in ARC mode:
 //
 // - NSInvocation's [get/set]ReturnValue and [get/set]Argument are only safe
 //   with __unsafe_unretained objects.
 // - When a NSData's 'bytes' family of methods are used on a local var,
 //   add __attribute__((objc_precise_lifetime)) to make it safer.
+// - Calling -zone gets replaced with 'nil'.
 //
 //===----------------------------------------------------------------------===//
 
 #include "Transforms.h"
 #include "Internals.h"
+#include "clang/Sema/SemaDiagnostic.h"
 
 using namespace clang;
 using namespace arcmt;
@@ -35,6 +37,8 @@ class APIChecker : public RecursiveASTVisitor<APIChecker> {
 
   Selector bytesSel, getBytesSel, getBytesLengthSel, getBytesRangeSel;
 
+  Selector zoneSel;
+
   llvm::DenseSet<VarDecl *> ChangedNSDataVars;
 public:
   APIChecker(MigrationPass &pass) : Pass(pass) {
@@ -57,9 +61,12 @@ public:
     getBytesLengthSel = sels.getSelector(2, selIds);
     selIds[1] = &ids.get("range");
     getBytesRangeSel = sels.getSelector(2, selIds);
+
+    zoneSel = sels.getNullarySelector(&ids.get("zone"));
   }
 
   bool VisitObjCMessageExpr(ObjCMessageExpr *E) {
+    // NSInvocation.
     if (E->isInstanceMessage() &&
         E->getReceiverInterface() &&
         E->getReceiverInterface()->getName() == "NSInvocation") {
@@ -91,6 +98,7 @@ public:
       return true;
     }
 
+    // NSData.
     if (E->isInstanceMessage() &&
         E->getReceiverInterface() &&
         E->getReceiverInterface()->getName() == "NSData" &&
@@ -111,6 +119,20 @@ public:
           }
     }
 
+    // -zone.
+    if (E->isInstanceMessage() &&
+        E->getInstanceReceiver() &&
+        E->getSelector() == zoneSel &&
+        Pass.TA.hasDiagnostic(diag::err_unavailable,
+                              diag::err_unavailable_message,
+                              E->getInstanceReceiver()->getExprLoc())) {
+      // Calling -zone is meaningless in ARC, change it to nil.
+      Transaction Trans(Pass.TA);
+      Pass.TA.clearDiagnostic(diag::err_unavailable,
+                              diag::err_unavailable_message,
+                              E->getInstanceReceiver()->getExprLoc());
+      Pass.TA.replace(E->getSourceRange(), getNilString(Pass.Ctx));
+    }
     return true;
   }
 };