r229402 - Fix crash when clang tries to build NSNumber literal after forward declaration

[jahanian]

You are right. It is more code to move this into where check is made for !S.NSNumberDecl as NSNumberPointer
need be initialized in couple of places. Your patch is fine.
- Fariborz

> On Feb 16, 2015, at 11:38 AM, AlexDenisov <1101.debian at gmail.com> wrote:
> 
> Well, it was there.
> Let’s consider we have this code:
> 
> @class NSNumber;
> 
> void checkNSNumberFDDiagnostic() {
>     id num = @1000;
> }
> 
> @interface NSNumber
> + (NSNumber *)numberWithInt:(int)value;
> @end
> 
> int main() {
>     id num = @1000;
> }
> 
> Parser finds first @1000 and tries to create literal expression, S.NSNumberDecl is nil in this case, so it created NSNumberDecl from forward declaration _and_ it fills NSNumberPointer with NULL type and then fails with error, because class NSNumber is not defined.
> 
> Then, is finds second @1000 and tries to create literal, NSNumber is defined now and has numberWithInt method, everything is fine and seems legit. Then it finally attempts to create literal and passes there NULL type (NSNumberPointer), which is cause the crash.
> 
> Maybe I used a wrong place to solve the problem, but it’s the only place that I’ve found.
> I’d appreciate any suggestions how to improve this code.
> -- 
> AlexDenisov
> Software Engineer, https://github.com/AlexDenisov <https://github.com/AlexDenisov>
> On 16 Feb 2015 at 20:26:56, jahanian (fjahanian at apple.com <mailto:fjahanian at apple.com>) wrote:
> 
>> 
>>> On Feb 16, 2015, at 8:17 AM, Alex Denisov <1101.debian at gmail.com <mailto:1101.debian at gmail.com>> wrote:
>>> 
>>> Author: alexdenisov
>>> Date: Mon Feb 16 10:17:05 2015
>>> New Revision: 229402
>>> 
>>> URL: http://llvm.org/viewvc/llvm-project?rev=229402&view=rev <http://llvm.org/viewvc/llvm-project?rev=229402&view=rev>
>>> Log:
>>> Fix crash when clang tries to build NSNumber literal after forward declaration
>>> 
>>> Bug report: http://llvm.org/bugs/show_bug.cgi?id=22561 <http://llvm.org/bugs/show_bug.cgi?id=22561>
>>> 
>>> Clang tries to create ObjCBoxedExpression of type 'NSNumber'
>>> when 'NSNumber' has only forward declaration, this cause a crash later,
>>> when 'Sema' refers to a nil QualType of the whole expression.
>>> Please, refer to the bug report for the better explanation.
>>> 
>>> 
>>> Modified:
>>>    cfe/trunk/lib/Sema/SemaExprObjC.cpp
>>>    cfe/trunk/test/SemaObjC/objc-literal-nsnumber.m
>>> 
>>> Modified: cfe/trunk/lib/Sema/SemaExprObjC.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprObjC.cpp?rev=229402&r1=229401&r2=229402&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprObjC.cpp?rev=229402&r1=229401&r2=229402&view=diff>
>>> ==============================================================================
>>> --- cfe/trunk/lib/Sema/SemaExprObjC.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaExprObjC.cpp Mon Feb 16 10:17:05 2015
>>> @@ -218,7 +218,9 @@ static ObjCMethodDecl *getNSNumberFactor
>>>       S.Diag(Loc, diag::err_undeclared_nsnumber);
>>>       return nullptr;
>>>     }
>>> -    
>>> +  }
>>> +
>>> +  if (S.NSNumberPointer.isNull()) {
>> 
>> Creation of NSNumberPointer should go inside if (!S.NSNumberDecl) 
>> which is right before this code. 
>> 
>> - Fariborz
>> 
>>>     // generate the pointer to NSNumber type.
>>>     QualType NSNumberObject = CX.getObjCInterfaceType(S.NSNumberDecl);
>>>     S.NSNumberPointer = CX.getObjCObjectPointerType(NSNumberObject);
>>> 
>>> Modified: cfe/trunk/test/SemaObjC/objc-literal-nsnumber.m
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/objc-literal-nsnumber.m?rev=229402&r1=229401&r2=229402&view=diff <http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaObjC/objc-literal-nsnumber.m?rev=229402&r1=229401&r2=229402&view=diff>
>>> ==============================================================================
>>> --- cfe/trunk/test/SemaObjC/objc-literal-nsnumber.m (original)
>>> +++ cfe/trunk/test/SemaObjC/objc-literal-nsnumber.m Mon Feb 16 10:17:05 2015
>>> @@ -9,6 +9,24 @@ typedef unsigned int NSUInteger;
>>> typedef int NSInteger;
>>> #endif
>>> 
>>> +void checkNSNumberUnavailableDiagnostic() {
>>> +  id num = @1000; // expected-error {{NSNumber must be available to use Objective-C literals}}
>>> +
>>> +  int x = 1000;
>>> +  id num1 = @(x); // expected-error {{NSNumber must be available to use Objective-C literals}}\
>>> +                  // expected-error {{illegal type 'int' used in a boxed expression}}
>>> +}
>>> +
>>> + at class NSNumber;
>>> +
>>> +void checkNSNumberFDDiagnostic() {
>>> +  id num = @1000; // expected-error {{NSNumber must be available to use Objective-C literals}}
>>> +
>>> +  int x = 1000;
>>> +  id num1 = @(x); // expected-error {{declaration of 'numberWithInt:' is missing in NSNumber class}}\
>>> +                  // expected-error {{illegal type 'int' used in a boxed expression}}
>>> +}
>>> +
>>> @interface NSObject
>>> + (NSObject*)nsobject;
>>> @end
>>> 
>>> 
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