Re: [PATCH] gdb/testsuite: fix gdb.python/py-events.exp for finding process id

[Andrew Burgess <aburgess@redhat.com>]

* Tankut Baris Aktemur via Gdb-patches <gdb-patches@sourceware.org> [2022-01-12 10:51:51 +0100]:

> When executed with --target_board=native-extended-gdbserver, the
> gdb.python/py-events.exp test errors out with
> 
>   ERROR: tcl error sourcing /path/to/gdb/testsuite/gdb.python/py-events.exp.
>   ERROR: can't read "process_id": no such variable
>       while executing
>   "lappend expected "ptid: \\($process_id, $process_id, 0\\)" "address: $addr""
>       (file "/path/to/gdb/testsuite/gdb.python/py-events.exp" line 103)
>       invoked from within
>   "source /path/to/gdb/testsuite/gdb.python/py-events.exp"
>       ("uplevel" body line 1)
>       invoked from within
>   "uplevel #0 source /path/to/gdb/testsuite/gdb.python/py-events.exp"
>       invoked from within                                                                                                                                                                       "catch "uplevel #0 source $test_file_name""
> 
> There are multiple problems around this:
> 
> 1. The process_id variable is not initialized to a default value.
> 
> 2. The test attempts to find the PID of the current thread, but the
>    regexp that it uses is not tailored for the output printed by the
>    remote target.
> 
> 3. The test uses "info threads" to find the current thread PID.
>    Using the "thread" command instead is simpler.
> 
> Fix these problems.
> ---
>  gdb/testsuite/gdb.python/py-events.exp | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.python/py-events.exp b/gdb/testsuite/gdb.python/py-events.exp
> index 4df012b943b..4b411999588 100644
> --- a/gdb/testsuite/gdb.python/py-events.exp
> +++ b/gdb/testsuite/gdb.python/py-events.exp
> @@ -81,12 +81,17 @@ delete_breakpoints
>  
>  # Test inferior call events
>  
> -gdb_test_multiple "info threads" "get current thread" {
> -    -re -wrap "process ($decimal)\[^\n\r\]*do_nothing.*" {
> +set process_id 0

This looks good.  My only suggestion would be don't initialise
process_id to a number.  I know it's pretty unlikely that `0` is ever
going to be a valid result, but it's not impossible.

If you instead initialise to something like "invalid" then there's
even less chance that this will match the actual output.

With that change this is good to apply.

Thanks,
Andrew


> +gdb_test_multiple "thread" "get current thread" {
> +    -re -wrap "process ($decimal).*" {
>  	set process_id $expect_out(1,string)
>  	pass $gdb_test_name
>      }
> -    -re -wrap "Thread $hex \\(LWP ($decimal)\\)\[^\n\r\]*do_nothing.*" {
> +    -re -wrap "Thread $hex \\(LWP ($decimal)\\).*" {
> +	set process_id $expect_out(1,string)
> +	pass $gdb_test_name
> +    }
> +    -re -wrap "Thread $decimal\.($decimal).*" {
>  	set process_id $expect_out(1,string)
>  	pass $gdb_test_name
>      }
> -- 
> 2.33.1
> 
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