[Bug symtab/31745] New: [gdb/symtab] Can't print pre-defined macros with binaries built with clang -save-temps

[Bug symtab/31745] New: [gdb/symtab] Can't print pre-defined macros with binaries built with clang -save-temps

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31745

            Bug ID: 31745
           Summary: [gdb/symtab] Can't print pre-defined macros with
                    binaries built with clang -save-temps
           Product: gdb
           Version: HEAD
            Status: NEW
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: vries at gcc dot gnu.org
  Target Milestone: ---

Consider a hello world compiled with clang:
...
$ clang-15 -gdwarf-5 -g3 -fdebug-macro ~/data/hello.c
...

Printing a pre-defined macro works fine (thanks to commit e7e7469e7a3 "gdb: Fix
issue with Clang CLI macros", the fix for PR29034):
...
$ gdb -q -batch a.out -ex start -ex "p __DBL_MAX__"
Temporary breakpoint 1 at 0x6af: file /home/vries/data/hello.c, line 6.

Temporary breakpoint 1, main () at /home/vries/data/hello.c:6
6         printf ("hello\n");
$1 = 1.7976931348623157e+308
...

However, if we add -save-temps:
...
$ clang-15 -gdwarf-5 -g3 -fdebug-macro ~/data/hello.c -save-temps
hello.s:4:2: warning: inconsistent use of MD5 checksums
        .file   1 "/home/vries" "data/hello.c"
        ^
...
we get:
...
$ gdb -q -batch a.out -ex start -ex "p __DBL_MAX__"
Temporary breakpoint 1 at 0x6af: file /home/vries/data/hello.c, line 6.

Temporary breakpoint 1, main () at /home/vries/data/hello.c:6
6         printf ("hello\n");
No symbol "__DBL_MAX__" in current context.
...

It's possible something is wrong with the debug info, so let's try to see what
lldb does:
...
$ lldb -b a.out -o "b main" -o run -o "print __DBL_MAX__"
(lldb) target create "a.out"
Current executable set to '/home/vries/gcc/a.out' (x86_64).
(lldb) b main
Breakpoint 1: where = a.out`main + 15 at hello.c:6:3, address =
0x00000000000006af
(lldb) run
Process 10477 stopped
* thread #1, name = 'a.out', stop reason = breakpoint 1.1
    frame #0: 0x00005555555546af a.out`main at hello.c:6:3
   3    int
   4    main (void)
   5    {
-> 6      printf ("hello\n");
   7      return 0;
   8    }

Process 10477 launched: '/home/vries/gcc/a.out' (x86_64)
(lldb) print __DBL_MAX__
(double) $0 = 1.7976931348623157E+308
...

It has no problems getting the info, which would suggest that gdb could be
fixed as well.

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[Bug symtab/31745] [gdb/symtab] Can't print pre-defined macros with binaries built with clang -save-temps

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31745

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
With this:
...
diff --git a/gdb/dwarf2/macro.c b/gdb/dwarf2/macro.c
index a511d0a3b44..6686fd84f49 100644
--- a/gdb/dwarf2/macro.c
+++ b/gdb/dwarf2/macro.c
@@ -838,6 +838,12 @@ dwarf_decode_macros (dwarf2_per_objfile *per_objfile,

   do
     {
+      if (producer_is_clang (cu))
+       {
+         current_file = macro_start_file (builder, 1, 0, nullptr, lh);
+         break;
+       }
+
       /* Do we at least have room for a macinfo type byte?  */
       if (mac_ptr >= mac_end)
        {
...
we get:
...
$ gdb -q -batch a.out -ex start -ex "p __DBL_MAX__"
Temporary breakpoint 1 at 0x6af: file /home/vries/data/hello.c, line 6.

Temporary breakpoint 1, main () at /home/vries/data/hello.c:6
6         printf ("hello\n");
$1 = 1.7976931348623157e+308
...

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[Bug macros/31745] [gdb/macros] Can't print pre-defined macros with binaries built with clang -save-temps

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31745

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[gdb/symtab] Can't print    |[gdb/macros] Can't print
                   |pre-defined macros with     |pre-defined macros with
                   |binaries built with clang   |binaries built with clang
                   |-save-temps                 |-save-temps
          Component|symtab                      |macros

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