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From: Zack Weinberg <zackw@panix.com>
Date: Fri, 30 Jun 2017 00:28:00 -0000
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Subject: Re: [RFC PATCH 0/3] Pretty-printing for errno
To: Pedro Alves <palves@redhat.com>
Cc: Phil Muldoon <pmuldoon@redhat.com>, GNU C Library <libc-alpha@sourceware.org>, gdb@sourceware.org, 	Joseph Myers <joseph@codesourcery.com>, Florian Weimer <fweimer@redhat.com>, tom@tromey.com, 	Siddhesh Poyarekar <siddhesh@gotplt.org>
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On Thu, Jun 29, 2017 at 1:28 PM, Pedro Alves <palves@redhat.com> wrote:
> With this code:
>
>  typedef int zzz;
>  zzz z;
>
> gdb:
>
>  (gdb) whatis z
>  type = zzz
>  (gdb) whatis (zzz)0
>  type = zzz
>  (gdb) whatis zzz
>  type = int

For the glibc patch to go through, this case also needs to work:

typedef int error_t;
error_t var;
extern error_t *errloc(void);

int main(void)
{
    return *errloc();
}

(compiled to .o file)

(gdb) ptype errloc
No symbol "errloc" in current context.

This might be a problem with inadequate debugging information
generated by the compiler -- it does work correctly if a function
*definition* is visible.  But we need it to work given only the above,
possibly with no debug symbols in the shared library defining
"errloc".

zw