[RFC][gdb/testsuite] Add -lbl option in gdb_test_multiple

[Pedro Alves]

On 2/21/20 3:35 PM, Tom de Vries wrote:

> I think we don't want to integrate -lbl in the user_code parsing, because:
> ...
> gdb_test_multiple "command" "testname" {
> 	-re "bla" {
> 	}
> 	-lbl
> }
> ...
> and:
> ...
> gdb_test_multiple "command" "testname" {
> 	-lbl
> 	-re "bla" {
> 	}
> }
> ...
> will have the same effect, which is likely to cause confusion.

Well:

 gdb_test_multiple "command" "testname" {
	-re "bar" {
	}
	-timeout 60
 }

and:

 gdb_test_multiple "command" "testname" {
	-timeout 60
	-re "bla" {
	}
 }

also have the same effect.  So there's precedent and it goes
all the way back to expect.

> [gdb/testsuite] Add -lbl option in gdb_test_multiple
> 
> Add gdb_test_multiple option -lbl, that adds a regexp after the user code that
> reads one line, and discards it:
> ...
>            -re "\r\n\[^\r\n\]*(?=\r\n)" {
>                exp_continue
>            }
> ...
> 
> In order to be able to write:
> ...
> gdb_test_multiple "command" "testname" {
>   ...
> } -lbl
> ...
> as opposed to having to insert the "" for the prompt_regexp arguments:
> ...
> gdb_test_multiple "command" "testname" {
>   ...
> } "" -lbl
> ...
> rewrite the promp_regexp argument usage into:
> ...
> gdb_test_multiple "command" "testname" {
>   ...
> } -prompt $prompt_regexp
> ...

Honestly, to me, this:

 gdb_test_multiple "command" "testname" {
   ...
 } -lbl -prompt $prompt_regexp

looks a bit harder to grok than:

 gdb_test_multiple "command" "testname" {
   -lbl
   -prompt $prompt_regexp
   ...
 }

... because those options appear at the end, after the regexes.

Alternatively, if you don't like the -lbl within the {} block, and if
we're going to use "-" options, how about supporting them before
the {} user code block, so that the user code block is always
at the end?  Like:

 gdb_test_multiple "command" "testname" -lbl {
   ...
 }

 gdb_test_multiple "command" "testname" -prompt $prompt_regexp {
   ...
 }

That should be doable with:

 -proc gdb_test_multiple { command message user_code { prompt_regexp "" } } {
 +proc gdb_test_multiple { command message args } {

and then walking the $args list, processing "-" arguments, and interpreting
the first non-"-" argument as the user code block (and erroring out if there
are more arguments).  I think the gdb_test_multiple code would look quite similar
to your patch, except that the user_code parameter would no longer be a parameter,
instead it would be a local variable set to the first non-"-" element of $args.

Thanks,
Pedro Alves