From <http://sourceware.org/ml/gdb-patches/2010-06/msg00365.html>:

On Friday 21 May 2010 21:35:37, Pierre Muller wrote:

> > Pierre> 2010-05-21  Pierre Muller  <muller@ics.u-strasbg.fr>
> > Pierre> 	* dwarf2read.c (process_die): Also allow DW_TAG_const_type
> > Pierre> 	and DW_TAG_volatile_type.
> > Pierre> 	(new_symbol): Likewise.

caused

 @@ -7385,16 +7385,16 @@ PASS: gdb.base/sigaltstack.exp: handle S
  PASS: gdb.base/sigaltstack.exp: handle SIGVTALRM print pass nostop
  PASS: gdb.base/sigaltstack.exp: handle SIGPROF print pass nostop
  PASS: gdb.base/sigaltstack.exp: break catcher if level == INNER
 -PASS: gdb.base/sigaltstack.exp: continue to catch
 +FAIL: gdb.base/sigaltstack.exp: continue to catch (the program exited)
  PASS: gdb.base/sigaltstack.exp: next
 -PASS: gdb.base/sigaltstack.exp: backtrace
 -PASS: gdb.base/sigaltstack.exp: finish from catch LEAF
 -PASS: gdb.base/sigaltstack.exp: finish to throw INNER
 -PASS: gdb.base/sigaltstack.exp: finish to catch INNER
 -PASS: gdb.base/sigaltstack.exp: finish from catch INNER
 -PASS: gdb.base/sigaltstack.exp: finish to OUTER
 -PASS: gdb.base/sigaltstack.exp: finish to catch MAIN
 -PASS: gdb.base/sigaltstack.exp: finish to MAIN
 +FAIL: gdb.base/sigaltstack.exp: backtrace (pattern 1)
 +FAIL: gdb.base/sigaltstack.exp: finish from catch LEAF (the program is no
longer running)
 +FAIL: gdb.base/sigaltstack.exp: finish to throw INNER (the program is no
longer running)
 +FAIL: gdb.base/sigaltstack.exp: finish to catch INNER (the program is no
longer running)
 +FAIL: gdb.base/sigaltstack.exp: finish from catch INNER (the program is no
longer running)
 +FAIL: gdb.base/sigaltstack.exp: finish to OUTER (the program is no longer running)
 +FAIL: gdb.base/sigaltstack.exp: finish to catch MAIN (the program is no longer
running)
 +FAIL: gdb.base/sigaltstack.exp: finish to MAIN (the program is no longer running)


The problem is in the `level' variable in the test.


 (gdb) break catcher if level == INNER
 A syntax error in expression, near `== INNER'.
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 (gdb) PASS: gdb.base/sigaltstack.exp: break catcher if level == INNER
 continue
 Continuing.

 Program received signal SIGALRM, Alarm clock.

 Program received signal SIGVTALRM, Virtual timer expired.

 Program exited with code 03.
 (gdb) FAIL: gdb.base/sigaltstack.exp: continue to catch (the program exited)
 ...

Note that the variable has the same name as the enum:

 enum level { MAIN, OUTER, INNER, LEAF, NR_LEVELS };

 /* Levels completed flag.  */
 volatile enum level level = NR_LEVELS;


It boils down to this --- before the patch, running sigaltstack
under gdb (run to main):

 (gdb) p level
 $1 = NR_LEVELS
 (gdb) ptype level
 type = volatile enum level {MAIN, OUTER, INNER, LEAF, NR_LEVELS}

and after the patch:

 (gdb) p level
 Attempt to use a type name as an expression
 (gdb) ptype level
 type = volatile enum level {MAIN, OUTER, INNER, LEAF, NR_LEVELS}