[Bug gdb/31563] Problems with accessing errno

["kevinb at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=31563

Kevin Buettner <kevinb at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #4 from Kevin Buettner <kevinb at redhat dot com> ---
Regarding the type of __errno_location...

When I run the test, compiled with -g3, on a machine without installed glibc
debuginfo and also with debuginfod disabled, I see:

(gdb) p errno
'__errno_location' has unknown return type; cast the call to its declared
return type

But, when I look at the DWARF for the binary, I see:

 <1><32>: Abbrev Number: 2 (DW_TAG_subprogram)
    <33>   DW_AT_external    : 1
    <33>   DW_AT_name        : (indirect string, offset: 0x1f7e):
__errno_location
    <37>   DW_AT_decl_file   : 2
    <38>   DW_AT_decl_line   : 37
    <39>   DW_AT_decl_column : 13
    <3a>   DW_AT_prototyped  : 1
    <3a>   DW_AT_type        : <0x3e>
    <3e>   DW_AT_declaration : 1
 <1><3e>: Abbrev Number: 3 (DW_TAG_pointer_type)
    <3f>   DW_AT_byte_size   : 8
    <40>   DW_AT_type        : <0x44>
 <1><44>: Abbrev Number: 4 (DW_TAG_base_type)
    <45>   DW_AT_byte_size   : 4
    <46>   DW_AT_encoding    : 5        (signed)
    <47>   DW_AT_name        : int

So gdb could know the type if it didn't ignore it.  (It is ignored in
read_func_scope in gdb/dwarf2/read.c due to not having low and high pc
attributes.)

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