[gdb/testsuite] Add debug prints in Term::wait_for

The semantics of wait_for are non-trivial, and a bit hard to understand
sometimes.

Add some debug prints in wait_for that make it clear:
- what regexps we're trying to match,
- what strings we compare to the regexps, and
- whether there's a match or mismatch.

I've added this ad-hoc a couple of times, and it seems that it's worth having
readily available.

The debug prints are enabled by adding DEBUG_TUI_MATCHING=1 to the
RUNTESTFLAGS:
...
$ make check RUNTESTFLAGS="gdb.tui/empty.exp DEBUG_TUI_MATCHING=1"
...

Tested on x86_64-linux.

diff --git a/gdb/testsuite/lib/tuiterm.exp b/gdb/testsuite/lib/tuiterm.exp
index ff38af082dab97dd6f44c60ffaf410ba91e36d3d..bb462911046e82c4a7d8afcbce15bfed76836f3a 100644 (file)
--- a/gdb/testsuite/lib/tuiterm.exp
+++ b/gdb/testsuite/lib/tuiterm.exp
@@ -716,6 +716,20 @@ namespace eval Term {
        return 1
     }
 
+    # Print arg using "verbose -log" if DEBUG_TUI_MATCHING == 1.
+    proc debug_tui_matching { arg } {
+       set debug 0
+       if { [info exists ::DEBUG_TUI_MATCHING] } {
+           set debug $::DEBUG_TUI_MATCHING
+       }
+
+       if { ! $debug } {
+           return
+       }
+
+       verbose -log "$arg"
+    }
+
     # Accept some output from gdb and update the screen.  WAIT_FOR is
     # a regexp matching the line to wait for.  Return 0 on timeout, 1
     # on success.
@@ -724,7 +738,10 @@ namespace eval Term {
        variable _cur_col
        variable _cur_row
 
+       set fn "wait_for"
+       
        set prompt_wait_for "$gdb_prompt \$"
+       debug_tui_matching "$fn: regexp: '$wait_for'"
 
        while 1 {
            if { [accept_gdb_output] == 0 } {
@@ -740,10 +757,14 @@ namespace eval Term {
                set prev [get_line $_cur_row]
            }
            if {[regexp -- $wait_for $prev]} {
+               debug_tui_matching "$fn: match: '$prev'"
                if {$wait_for == "$prompt_wait_for"} {
                    break
                }
                set wait_for $prompt_wait_for
+               debug_tui_matching "$fn: regexp prompt: '$wait_for'"
+           } else {
+               debug_tui_matching "$fn: mismatch: '$prev'"
            }
        }