[Bug fortran/32732] [Bind C] Character scalars are passed as arrays

[Christopher D. Rickett]

hi Steve,

>> second, i think i've tracked down what was causing the problem with the
>> code snippet.  the call to sub0 gets converted (gfc_conv_function_call)
>> before the generate_local_decls runs for param_test.  this means that the
>> symbols for the dummy args in the call still say they're an array_type, so
>> the actuals given by sub0() are converted to array_type.  i think this
>> means that the fixup done for by-value character dummies in
>> generate_local_decl must also be done when mapping actuals to formals in
>> gfc_conv_function_call.  i've attached a patch that does this.  it's been
>> bootstrapped and regtested on x86 and x86_64 linux with no new failures,
>> but the real test is whether they'll work for you.  :-)
>
> It doesn't look like it is working.  I put in your patch (after removing
> the previous trans-decl.c patch) Then I rebuilt and tested my program
> and it still failed.  Looking at the assembly language, there are still
> shifts of the characters in sub0 before it calls param_test so it looks
> like sub0 is still passing the arguments as arrays.
>
> I am not sure why this is, I do hit the new code in trans-expr.c, before
> calling gfc_conv_scalar_char_value I have:
>
> <parm_decl 7d6cc2d8 my_char
>    type <array_type 7d76e230
>        type <integer_type 7d6d8150 char public unsigned string-flag QI
>            size <integer_cst 7d6c51b8 constant invariant 8>
>            unit size <integer_cst 7d6c51e0 constant invariant 1>
>            align 8 symtab 0 alias set -1 canonical type 7d6d8150 precision 8 min <integer_cst 7d6c5208 0> max <integer_cst 7d6c5230 255>
>            pointer_to_this <pointer_type 7d6e0690>>
>        string-flag QI size <integer_cst 7d6c51b8 8> unit size <integer_cst 7d6c51e0 1>
>        align 8 symtab 0 alias set -1 canonical type 7d76e230
>        domain <integer_type 7d76e1c0 type <integer_type 7d6d8310 int4>
>            SI
>            size <integer_cst 7d6c53e8 constant invariant 32>
>            unit size <integer_cst 7d6c50f0 constant invariant 4>
>            align 32 symtab 0 alias set -1 canonical type 7d76e1c0 precision 32 min <integer_cst 7d6c5898 1> max <integer_cst 7d6c5898 1>>>
>    readonly QI file x.f90 line 5 size <integer_cst 7d6c51b8 8> unit size <integer_cst 7d6c51e0 1>
>    align 8 context <function_decl 7d76dd20 param_test> initial <array_type 7d76e230> arg-type <array_type 7d76e230> chain <parm_decl 7d6cc3a8 my_char_2>>
>
> And after calling gfc_conv_scalar_char_value I have:
>
> <parm_decl 7d6cc2d8 my_char
>    type <integer_type 7d6d8150 char public unsigned string-flag QI
>        size <integer_cst 7d6c51b8 constant invariant 8>
>        unit size <integer_cst 7d6c51e0 constant invariant 1>
>        align 8 symtab 0 alias set -1 canonical type 7d6d8150 precision 8 min <integer_cst 7d6c5208 0> max <integer_cst 7d6c5230 255>
>        pointer_to_this <pointer_type 7d6e0690>>
>    readonly QI file x.f90 line 5 size <integer_cst 7d6c51b8 8> unit size <integer_cst 7d6c51e0 1>
>    align 8 context <function_decl 7d76dd20 param_test> initial <integer_type 7d6d8150 char> arg-type <integer_type 7d6d8150 char> chain <parm_decl 7d6cc3a8 my_char_2>>
>
> But the arguments are still shifted before being passed from sub0 to
> param_test.  I don't know why.
>

thanks for trying it out.  i'm quite at a loss now as to why it's failing; 
i thought that fixing the array_type still being seen in 
gfc_conv_function_call would do it.  now i'm not even sure where to start 
looking...  the only thing i could think to do now is to run cc1 through 
gdb and figure out what the C frontend is doing with characters that isn't 
happening on the fortran side.  it would be good to see the debug_tree 
output for the tree created by cc1, but that would be a bit more work for 
you.  i'll see if i can figure out where to put the call to debug_tree and 
maybe pass it on to you.

thanks again for all of the help.
Chris