[Patch, fortran, 4.9] Use bool type instead gfc_try

[N.M. Maclaren]

On Mar 22 2013, Tobias Burnus wrote:
>
>The front end and the backend are both compiled with the same compiler 
>and in the same binary. Even without bootstrapping, trying to compile 
>them with different compilers, will require some heavy editing of 
>makefiles. Thus, it seems to be extremely unlikely that different 
>compilers have ever been used.  The change from C99's bool to C++'s bool 
>occurred for the whole compiler. Before 4.7 the default was to compile 
>GCC with C (though it had been modified to be also compilable with C++); 
>in 4.7, the default compiler was C++ but C was still supported. And 
>since GCC 4.8 C++ features are used, which makes GCC only compilable 
>with C++. Actually, the FE itself so far uses nearly no C++ features, it 
>is the middle end which used them (which 'leak' to the front end via 
>some helper macros/functions).

Ah.  I misunderstood what people said.  Yes, if C++ mode is used for
the whole compiler, everything is fine.  And it remains so even if
the code plays fairly clever games.  I don't know if there are any
compilers that generate incompatible bool types in C and C++ modes,
but it wouldn't surprise me if there were.

>In terms of the discussion, "bool" is used for quite some time in 
>gfortran (the frontend) and libgfortran. When GCC was compiled with C, 
>that was C99's _Bool. Since the compiler is compiled as C++, it is C++'s 
>"bool". Thus, C/C++'s bool are never mixed.

Then there is no problem.  Sorry about the red herring - I misunderstood
what people said.  Unfortunately, from personal experience, the majority 
of people even on WG14 and WG21 do not understand the incompatibilities,
which is why I posted.


Regards,
Nick Maclaren.