[gdb/symtab] Fix incorrect filenames with inter-CU refs

With target board unix we get:
...
$ gdb -q -batch outputs/gdb.cp/cplusfuncs/cplusfuncs \
  -ex "info function operator\*"
All functions matching regular expression "operator\*":

File /home/vries/gdb/src/gdb/testsuite/gdb.cp/cplusfuncs.cc:
72:     void foo::operator*(foo&);
85:     void foo::operator*=(foo&);
...
but with target board cc-with-dwz-m:
...
All functions matching regular expression "operator\*":

File /usr/lib/gcc/aarch64-redhat-linux/14/include/stddef.h:
72:     void foo::operator*(foo&);
85:     void foo::operator*=(foo&);
...

The first operator:
...
$ c++filt _ZN3foomlERS_
foo::operator*(foo&)
...
matches address 0x410250 which is defined here in the CU in the exec:
...
 <1><10f1>: Abbrev Number: 13 (DW_TAG_subprogram)
    <10f2>   DW_AT_specification: <alt 0x93>
    <10f6>   DW_AT_decl_line   : 72
    <10f7>   DW_AT_decl_column : 7
    <10f7>   DW_AT_object_pointer: <0x1106>
    <10f9>   DW_AT_low_pc      : 0x410250
    <1101>   DW_AT_high_pc     : 32
    <1102>   DW_AT_frame_base  : 1 byte block: 9c       (DW_OP_call_frame_cfa)
    <1104>   DW_AT_call_all_calls: 1
...
and declared here in the PU in the .dwz file:
...
 <2><93>: Abbrev Number: 20 (DW_TAG_subprogram)
    <94>   DW_AT_external    : 1
    <94>   DW_AT_name        : operator*
    <98>   DW_AT_decl_file   : 2
    <98>   DW_AT_decl_line   : 10
    <99>   DW_AT_decl_column : 9
    <9a>   DW_AT_linkage_name: _ZN3foomlERS_
    <9e>   DW_AT_accessibility: 1       (public)
    <9e>   DW_AT_declaration : 1
    <9e>   DW_AT_object_pointer: <0xa2>
...

When creating a new symbol for the operator, the DW_AT_decl_file attribute is
looked up, and found to be 2.

The 2 is supposed to be mapped using the PU, which has this file name table:
...
 The File Name Table (offset 0x78, lines 3, columns 2):
  Entry Dir     Name
  0     0       <dwz>
  1     1       stddef.h
  2     2       cplusfuncs.cc
...

Instead, it's mapped using the CU, which has this file name table:
...
 The File Name Table (offset 0x34, lines 3, columns 2):
  Entry Dir     Name
  0     1       cplusfuncs.cc
  1     1       cplusfuncs.cc
  2     2       stddef.h
...

This is PR symtab/30814.  There's a similar PR for lto, PR symtab/25771, where
the same problem happens for two CUs.

Fix this by using the correct file name table.

Add a dwarf assembly test-case for PR25771.

Tested on aarch64-linux.

Reviewed-By: Tom Tromey <tom@tromey.com>

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=25771
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30814

1 files changed, 4 insertions, 0 deletions

diff --git a/gdb/testsuite/lib/dwarf.exp b/gdb/testsuite/lib/dwarf.exp
index f9be6c4..6a5afec 100644
--- a/gdb/testsuite/lib/dwarf.exp
+++ b/gdb/testsuite/lib/dwarf.exp
@@ -887,6 +887,10 @@ namespace eval Dwarf {
 	    DW_AT_GNU_addr_base {
 		return DW_FORM_sec_offset
 	    }
+	    DW_AT_decl_file -
+	    DW_AT_decl_line {
+		return DW_FORM_udata
+	    }
 	}
 	return ""
     }