[cfe-dev] [patch] _Generic constant string used as controlling expression

[Richard Smith]

On Mon, Apr 28, 2014 at 10:58 AM, Prathamesh Kulkarni <
bilbotheelffriend at gmail.com> wrote:

> Hi,
>    I had reported this bug earlier:
>
> http://clang-developers.42468.n3.nabble.com/Generic-constant-string-as-controlling-expression-td4036519.html
>
> For following case:
> int main(void)
> {
>   int x = _Generic("hello", char *: 1);
> }
>
> clang gives error:
> generic_expr.c:3:20: error: controlling expression type 'char [6]' not
> compatible with any generic association type
>  int x = _Generic ("hello", char *: 1);
>
> I guess that's because array-to-pointer conversion is not performed
> when array is used as controlling expression.
> gcc-4.9 compiles the above test-case.
>
> I have attached a patch that performs array-to-pointer conversion
> when array is used as controlling expression, and it compiles the
> above test-case.
> OK to commit ?


This isn't quite the right approach -- it will still do the wrong thing if
a function designator is used as the argument to _Generic. You should use
DefaultFunctionArrayConversion here instead, replacing the existing
placeholder handling with it.
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