[gcc r14-6389] Add some new DW_IDX_* constants

[Tom Tromey]

https://gcc.gnu.org/g:748766b8f6237cd23b8e5f998fae39b31d2664d0

commit r14-6389-g748766b8f6237cd23b8e5f998fae39b31d2664d0
Author: Tom Tromey <tom@tromey.com>
Date:   Sat Dec 9 09:19:30 2023 -0700

    Add some new DW_IDX_* constants
    
    I've reimplemented the .debug_names code in GDB -- it was quite far
    from being correct, and the new implementation is much closer to what
    is specified by DWARF.
    
    However, the new writer in GDB needs to emit some symbol properties,
    so that the reader can be fully functional.  This patch adds a few new
    DW_IDX_* constants, and tries to document the existing extensions as
    well.  (My patch series add more documentation of these to the GDB
    manual as well.)
    
    include/ChangeLog
    2023-12-10  Tom Tromey  <tom@tromey.com>
    
            * dwarf2.def (DW_IDX_GNU_internal, DW_IDX_GNU_external): Comment.
            (DW_IDX_GNU_main, DW_IDX_GNU_language, DW_IDX_GNU_linkage_name):
            New constants.

Diff:
---
 include/dwarf2.def | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/dwarf2.def b/include/dwarf2.def
index 7ab3ee611fd..75b75d90188 100644
--- a/include/dwarf2.def
+++ b/include/dwarf2.def
@@ -802,8 +802,17 @@ DW_IDX (DW_IDX_parent, 4)
 DW_IDX (DW_IDX_type_hash, 5)
 DW_IDX_DUP (DW_IDX_lo_user, 0x2000)
 DW_IDX (DW_IDX_hi_user, 0x3fff)
+/* Internal linkage.  A flag.  */
 DW_IDX (DW_IDX_GNU_internal, 0x2000)
+/* External linkage.  A flag.  Note that gdb no longer generates this;
+   the default is to assume external linkage.  */
 DW_IDX (DW_IDX_GNU_external, 0x2001)
+/* This entry is the program's entry point.  A flag.  */
+DW_IDX (DW_IDX_GNU_main, 0x2002)
+/* Language for this entry.  A DW_LANG_* value.  */
+DW_IDX (DW_IDX_GNU_language, 0x2003)
+/* This entry is a linkage name.  A flag.  */
+DW_IDX (DW_IDX_GNU_linkage_name, 0x2004)
 DW_END_IDX
 
 /* DWARF5 Unit type header encodings  */