On 25/01/2014 01:24, Richard Smith wrote:
> On Fri Jan 24 2014 at 9:20:44 AM, Jordan Rose <jordan_rose at apple.com
> <mailto:jordan_rose at apple.com>> wrote:
>
>
> On Jan 24, 2014, at 2:51 , Pedro Delgado Perez
> <pedro.delgadoperez at mail.uca.es
> <mailto:pedro.delgadoperez at mail.uca.es>> wrote:
>
>> Hi,
>>
>> My question is simple. Could anyone explain me what's the
>> difference between the methods
>> getResultType and getCallResultType in FunctionDecl?
>>
>> This is the implementation in FunctionType:
>>
>> 02783 <http://clang.llvm.org/doxygen/classclang_1_1FunctionType.html#aafa453cd7e81a7c3d6c61f261e68afe8> QualType <http://clang.llvm.org/doxygen/classclang_1_1QualType.html> getResultType <http://clang.llvm.org/doxygen/classclang_1_1FunctionType.html#aafa453cd7e81a7c3d6c61f261e68afe8>() const{return ResultType; }
>>
>> ...
>> 02799 <http://clang.llvm.org/doxygen/classclang_1_1FunctionType.html#a5f8df0258bcf7281e7055ea01dbd8f85> QualType <http://clang.llvm.org/doxygen/classclang_1_1QualType.html> getCallResultType <http://clang.llvm.org/doxygen/classclang_1_1FunctionType.html#a5f8df0258bcf7281e7055ea01dbd8f85>(ASTContext <http://clang.llvm.org/doxygen/classclang_1_1ASTContext.html> &Context <http://clang.llvm.org/doxygen/ASTMatchFinder_8cpp.html#a779280869b9fac47a9bc391e7709171f>) const{2800return getResultType().getNonLValueExprType <http://clang.llvm.org/doxygen/classclang_1_1QualType.html#a89e3ea65c009b7a0ea76edc56076107c>(Context);2801 }
>>
>> And this is the definition ofgetNonLValueExprType
>> <http://clang.llvm.org/doxygen/classclang_1_1QualType.html#a89e3ea65c009b7a0ea76edc56076107c>:
>> Determine the type of a (typically non-lvalue) expression with
>> the specified result type.
>> This routine should be used for expressions for which the return
>> type is explicitly specified (e.g., in a cast or call) and isn't
>> necessarily an lvalue. It removes a top-level reference (since
>> there are no expressions of reference type) and deletes top-level
>> cvr-qualifiers from non-class types (in C++) or all types (in C).
>>
>> But I am not able to understand this very well. Could anyone give
>> me an example of the difference? Up to now, I have been using
>> getResultType, but now I have found getCallResultType and I'm not
>> sure what should I use.
>>
> I'm not 100% sure about this, but my understanding is:
>
> You can declare your function to return "const int", but the
> caller is just going to get an int. Similarly, if you declare your
> function to return "int &", the calling expression has type "int"
> but is marked as an lvalue.
>
> On the other hand, if you return "const int *", dropping the const
> would be incorrect. (And the same is actually true for "const int &".)
>
> Basically, if you want to know the type the function says it's
> returning, use getResultType(). If you want to know the type that
> the CallExpr will have, use getCallResultType().
>
>
> We should rename 'getResultType' to 'getReturnType' to clarify this
> (and to generally follow the standard terminology). This has been on
> my TODO list for a long time, but there's always been something more
> pressing to do...
Done in r200082
Alp.
>
>
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