[PATCH] Help compiler detect invalid code

[François Dumont]

On 9/27/19 2:11 PM, Jonathan Wakely wrote:
> On 19/09/19 22:27 +0200, François Dumont wrote:
>> Hi
>>
>> Â Â Â  I start working on making recently added constexpr tests to work 
>> in Debug mode.
>
> The attached patch seems to be necessary for that, right?
>
>
On my side I had done this, almost the same.

For the moment there is a FIXME in macros.h to find out how to generate 
a nice compilation error when the condition is not meant.

static_assert can't be called in this context, too bad.

I also try to define a function with a 
__attribute__((__error__("because"))) attribute. But when I make it 
constexpr gcc complains about missing definition. When I provide a 
definition gcc complains that this attribute must be on a declaration. 
And when I split declaration and definition gcc does not produce the 
expected compilation error.

Unless you have the solution I consider that we need help from the 
front-end.

For the moment if Debug mode finds a problem it will be reported as 
_M_error function not being constexpr !

François

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