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From: Thomas Koenig <tkoenig@netcologne.de>
Newsgroups: comp.lang.fortran
Subject: Re: nasty link problem with Gfortran and G++ (C++) ???
Date: Wed, 15 Jan 2025 07:10:34 -0000 (UTC)
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Lynn McGuire <lynnmcguire5@gmail.com> schrieb:
> On 1/14/2025 12:42 PM, Thomas Koenig wrote:
>> Lynn McGuire <lynnmcguire5@gmail.com> schrieb:
>> 
>>> I found and fixed the problem with my code along with one of my
>>> programmers.  I was not properly handling the size_t hidden argument
>>> length value that GFortran adds to the character string arguments in my
>>> C++ code.  Things are going better now.
>> 
>> Good to hear that.
>> 
>> Another thing that works well for gcc is to link everything with
>> the -flto option.
>> 
>> An example:
>> 
>> $ cat main.f90
>> program memain
>>    character *1 c
>>    call foo(c)
>>    print *,c
>> end
>> $ cat foo.c
>> void foo_(char *c)
>> {
>>    *c = 'A';
>> }
>> $ gfortran -flto  main.f90 foo.c
>> main.f90:3:13: warning: type of 'foo' does not match original declaration [-Wlto-type-mismatch]
>>      3 |   call foo(c)
>>        |             ^
>> foo.c:1:6: note: type mismatch in parameter 2
>>      1 | void foo_(char *c)
>>        |      ^
>> foo.c:1:6: note: type 'void' should match type 'long int'
>> foo.c:1:6: note: 'foo_' was previously declared here
>
> I will try it.

Just a warning - be prepared for loooong compile times.