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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Making the same mistake as the broken C interface to fortran
Date: Fri, 05 Jul 2019 18:44:56 +0100
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Xref: reader01.eternal-september.org comp.lang.ada:56823
Date: 2019-07-05T18:44:56+01:00
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Chris M Moore <zmower@ntlworld.com> writes:

> On 04/07/2019 09:38, Simon Wright wrote:
>> procedure Call is
>>     procedure Callee_C (C : Character)
>>     with
>>       Import,
>>       Convention => Fortran,
>>       External_Name => "callee_";
>>     procedure Callee_F (C : Interfaces.Fortran.Fortran_Character)
>>     with
>>       Import,
>>       Convention => Fortran,
>>       External_Name => "callee_";
>>     procedure Callee_S (S : String)
>>     with
>>       Import,
>>       Convention => Fortran,
>>       External_Name => "callee_";
>> begin
>>     Callee_C ('c');
>
> I've looked at the assembler for this.  Passing 'c' results in only a
> byte pushed to the stack.  And then (aha!) the address on the stack is
> placed in the rdi register.

Because all Fortran parameters are passed by reference.