[Bug symtab/31010] New: Evaluating "mixed-cased" fundamental types causes hangs/OOM due to full symtab expansion

["josh.cottingham at linaro dot org" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=31010

            Bug ID: 31010
           Summary: Evaluating "mixed-cased" fundamental types causes
                    hangs/OOM due to full symtab expansion
           Product: gdb
           Version: 13.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: symtab
          Assignee: unassigned at sourceware dot org
          Reporter: josh.cottingham at linaro dot org
  Target Milestone: ---

Attempting to evaluate "mixed/uper-case" C/C++ fundamental types (such as
"output LONG" or "output Int") will cause GDB to try to fully expand the whole
symbol table. Depending on how large the binary we are debugging, this could
cause GDB to hang for several minutes and has been observed to cause
Out-of-Memory issues on some circumstances.

Via a git bisect, it was observed that this regression first occurs on the
commit which enables the new DWARF indexer:
https://sourceware.org/pipermail/gdb-patches/2022-April/187417.html

Easiest way to reproduce this issue is to attempt to run GDB on a debug build
of GDB:

$ gdb ./gdb/gdb
(gdb) start
Temporary breakpoint 1 at 0x410675: file gdb.c, line 28.
Starting program: /path/to/binutils-gdb/gdb/gdb 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

Temporary breakpoint 1, main (argc=1, argv=0x7fffffffd578) at gdb.c:28
28        memset (&args, 0, sizeof args);
(gdb) output LONG
No symbol "LONG" in current context.

This will take ~20-30 seconds, though as stated above with larger binaries it
has been observed to take make longer or cause Out-of-Memory. Worth noting the
hang does not occur if we attempt to output other non-existent symbols such as
"output NOTREAL".

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