[cfe-dev] operator* sema bug

[Steve Naroff]

I have a look later today...

Glad to hear you are feeling better!

snaroff

On Dec 15, 2007, at 9:38 AM, Chris Lattner wrote:

>
> On Dec 14, 2007, at 11:57 PM, Oliver Hunt wrote:
>
>> So i'm looking at this failure:
>> typedef struct { char name[100]; } entry;
>> char f1(entry *e) { return *e->name; }
>>
>>
>> The problem appears to be CodeGenFunction::EmitScalarExpr being  
>> called on e->name as it believes
>> e->name is an array type rather than a scalar, so we assert.
>>
>> I'm not sure what the appropriate correction should be -- should i  
>> fix
>> CodeGenFunction::EmitLoadOfLValue
>> So that it can handle an array type -- emitting an array type as an  
>> lvalue should just be to emit a getElementPtr(array, 0)
>>
>> Or alternatively have a step during merge to convert *array to  
>> array[0]
>
> Hi Oliver,
>
> Sorry for the delay, I've been majorly sick since thursday night.  I  
> don't think this is a codegen bug, I think it's a sema bug:
>
> $ clang t3.c -ast-dump
> typedef char *__builtin_va_list;
> typedef struct <anonymous> entry;
>
> char f1(entry *e)
> (CompoundStmt 0x8061e0 <t3.c:2:19, col:38>
>   (ReturnStmt 0x8061d0 <col:21, col:32>
>     (UnaryOperator 0x8061b0 <col:28, col:32> 'char' prefix '*'
>       (MemberExpr 0x806180 <col:29, col:32> 'char [100]' ->name  
> 0x805f00
>         (DeclRefExpr 0x806160 <col:29> 'entry *' ParmVar='e'  
> 0x806120)))))
>
> Sema is properly inferring that the * has type char, but it isn't  
> inserting an implicit cast.  I'd expect to see something like this:
>
> clang t3.c -ast-dump
> typedef char *__builtin_va_list;
> typedef struct <anonymous> entry;
>
> char f1(entry *e)
> (CompoundStmt 0x8061e0 <t3.c:2:19, col:38>
>   (ReturnStmt 0x8061d0 <col:21, col:32>
>     (UnaryOperator 0x8061b0 <col:28, col:32> 'char' prefix '*'
>       (ImplicitCast char*
>         (MemberExpr 0x806180 <col:29, col:32> 'char [100]' ->name  
> 0x805f00
>           (DeclRefExpr 0x806160 <col:29> 'entry *' ParmVar='e'  
> 0x806120))))))
>
> Maybe Steve can take a look if he has a chance,
>
> -Chris
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