[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, 22 insertions, 6 deletions

diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 886d14f..6ac6f7c 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -17839,10 +17839,11 @@ dwarf_lang_to_enum_language (unsigned int lang)
   return language;
 }
 
-/* Return the named attribute or NULL if not there.  */
+/* Return the NAME attribute of DIE in *CU, or return NULL if not there.  Also
+   return in *CU the cu in which the attribute was actually found.  */
 
 static struct attribute *
-dwarf2_attr (struct die_info *die, unsigned int name, struct dwarf2_cu *cu)
+dwarf2_attr (struct die_info *die, unsigned int name, struct dwarf2_cu **cu)
 {
   for (;;)
     {
@@ -17862,7 +17863,7 @@ dwarf2_attr (struct die_info *die, unsigned int name, struct dwarf2_cu *cu)
 	break;
 
       struct die_info *prev_die = die;
-      die = follow_die_ref (die, spec, &cu);
+      die = follow_die_ref (die, spec, cu);
       if (die == prev_die)
 	/* Self-reference, we're done.  */
 	break;
@@ -17871,6 +17872,14 @@ dwarf2_attr (struct die_info *die, unsigned int name, struct dwarf2_cu *cu)
   return NULL;
 }
 
+/* Return the NAME attribute of DIE in CU, or return NULL if not there.  */
+
+static struct attribute *
+dwarf2_attr (struct die_info *die, unsigned int name, struct dwarf2_cu *cu)
+{
+  return dwarf2_attr (die, name, &cu);
+}
+
 /* Return the string associated with a string-typed attribute, or NULL if it
    is either not found or is of an incorrect type.  */
 
@@ -19037,17 +19046,24 @@ new_symbol (struct die_info *die, struct type *type, struct dwarf2_cu *cu,
       if (attr != nullptr)
 	sym->set_line (attr->constant_value (0));
 
+      struct dwarf2_cu *file_cu = cu;
       attr = dwarf2_attr (die,
 			  inlined_func ? DW_AT_call_file : DW_AT_decl_file,
-			  cu);
+			  &file_cu);
       if (attr != nullptr && attr->is_nonnegative ())
 	{
 	  file_name_index file_index
 	    = (file_name_index) attr->as_nonnegative ();
 	  struct file_entry *fe;
 
-	  if (cu->line_header != NULL)
-	    fe = cu->line_header->file_name_at (file_index);
+	  if (file_cu->line_header == nullptr)
+	    {
+	      file_and_directory fnd (nullptr, nullptr);
+	      handle_DW_AT_stmt_list (file_cu->dies, file_cu, fnd, {}, false);
+	    }
+
+	  if (file_cu->line_header != nullptr)
+	    fe = file_cu->line_header->file_name_at (file_index);
 	  else
 	    fe = NULL;