Re: [PATCH v4 2/2] gdb: Keep original IFUNC return type when target type is unknown

Muhammad Kamran <[email protected]> writes:

> When find_function_addr resolves a GNU IFUNC, it tries to replace the
> original function type with the resolved target type, or with the type
> returned by the resolver.  If neither source provides a useful return
> type, keep the return type from the original function value.
>
> This matters for internal inferior calls such as
> find_function_in_inferior ("malloc"), where GDB creates a synthetic
> function type with a known fallback return type.
>
> Remove the guard from the IFUNC inferior-call test so the no-debug
> resolver/no-debug target variants are tested too.

It is probably worth adding the Bug: link from the previous commit here
too.

> ---
>  gdb/infcall.c                        | 12 ++++++++++--
>  gdb/testsuite/gdb.base/gnu-ifunc.exp |  7 -------
>  2 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/gdb/infcall.c b/gdb/infcall.c
> index e6b24ff5310..077407073ac 100644
> --- a/gdb/infcall.c
> +++ b/gdb/infcall.c
> @@ -395,6 +395,9 @@ find_function_addr (struct value *function,
>  	     FUNCTION_TYPE have been asked for.  */
>  	  if (retval_type != NULL || function_type != NULL)
>  	    {
> +	      /* Default to original function type's return type.  Target type
> +		 replaces this only if it provides a usable return type.  */
> +	      value_type = ftype->target_type ();
>  	      type *target_ftype = find_function_type (funaddr);
>  	      /* If we don't have debug info for the target function,
>  		 see if we can instead extract the target function's
> @@ -403,8 +406,13 @@ find_function_addr (struct value *function,
>  		target_ftype = find_gnu_ifunc_target_type (resolver_addr);
>  	      if (target_ftype != NULL)
>  		{
> -		  value_type = check_typedef (target_ftype)->target_type ();
> -		  ftype = target_ftype;
> +		  struct type *target_value_type

I think you should drop the 'struct' here.  Newer GDB code avoids the
'struct' where possible.  This function has a mix so I think adopting
the new style would be best.

> +		    = check_typedef (target_ftype)->target_type ();
> +		  if (target_value_type != NULL)

Replace 'NULL' with 'nullptr' in new code please.

With those minor fixes:

Approved-By: Andrew Burgess <[email protected]>

Thanks,
Andrew