Re: [PATCH] Remove unneeded pattern matching in gdb.base/maint.exp

[Pedro Alves <palves at redhat dot com>]

On 12/02/2016 05:40 PM, Luis Machado wrote:

> Doesn't gdb_test_multiple already check for a trailing $gdb_prompt?

gdb_test does, but gdb_test_multiple does not.

What gdb_test_multiple has, is an internal pattern that
matches the prompt if no other user-specified pattern
matches:

	-re "\r\n$gdb_prompt $" {
	    if ![string match "" $message] then {
		fail "$message"
	    }
	    set result 1
	}

That's why the second regexp here:

   gdb_test_multiple "...." "...." {
      -re "some pattern $gdb_prompt $ {
      }
      -re ".*$gdb_prompt $ {
         fail "...."
      }
   }

... is unnecessary.

But the gdb_prompt match in the first regexp is absolutely
necessary, otherwise you leave it dangling in the expect
buffer and confuse whatever comes after.  Whether that
causes trouble or not in a given dejagnu invocation is racy,
depends on how much expect pulls in to its internal buffer
at a time.  Often, "make check-read1" will make such problems
more reproducible.  But just don't introduce the problem in
the first place, please.  :-)

Thanks,
Pedro Alves