[binutils-gdb] [gdb/testsuite] Fix gdb.python/py-selected-context.exp regexp

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5ac46e0aa6f18bb265fb4df3a3c9d1d15f2813d1

commit 5ac46e0aa6f18bb265fb4df3a3c9d1d15f2813d1
Author: Tom de Vries <[email protected]>
Date:   Wed Aug 19 10:35:20 2026 +0200

    [gdb/testsuite] Fix gdb.python/py-selected-context.exp regexp
    
    On ppc64-linux, with test-case gdb.python/py-selected-context.exp I run into:
    ...
    (gdb) info inferiors^M
      Num  Description       Connection           Executable        ^M
      1    <null>                                                   ^M
    * 2    <null>                                                   ^M
    (gdb) FAIL: $exp: check inferior 2 was selected
    ...
    
    In contrast, on x86_64-linux, I get:
    ...
    (gdb) info inferiors^M
      Num  Description       Connection           Executable        ^M
      1    <null>                                                   ^M
    * 2    <null>                                                   ^M
    (gdb) PASS: $exp: check inferior 2 was selected
    ...
    
    The output is identical, so it's surprising that there's a different
    outcome.
    
    The proc doing the check is:
    ...
    proc check_inferior { inf testname } {
        gdb_test "info inferiors" \
            "\r\n\\*\\s+[string_to_regexp $inf]\\s+\[^\r\n\]*(?=\r\n)" \
            $testname
    }
    ...
    
    The problem seems to be triggered by the lookahead part '(?=\r\n)': removing
    it makes the test pass.
    
    By switching on some debugging in gdb_test_multiple, we get this info:
    ...
    Looking to match ""(?:\r\n\*\s+2\s+[^\r\n]*(?=\r\n))\r\n\(gdb\) $""
    ...
    which shows that the lookahead '(?=\r\n)' is immediately followed by a '\r\n',
    making the lookahead superfluous.
    
    Still, the test should not fail.  It fails due to an expect bug [1][2].
    
    But, there's another problem with the regexp.
    
    If we use the same proc to try to match inferior 1, we get a FAIL on both
    setups:
    ...
    (gdb) info inferiors^M
      Num  Description       Connection           Executable        ^M
    * 1    <null>                                                   ^M
      2    <null>                                                   ^M
    (gdb) FAIL: $exp: check inferior 1 was selected
    ...
    
    The problem is that the regexp doesn't allow a line after the matching line.
    
    Fix this this by appending '.*' to the regexp.
    
    Doing so also has the effect that we no longer run into the expect problem.
    
    While we're at it, rewrite the regexp to a more modern form, and drop the
    unnecessary string_to_regexp:
    ...
            [multi_line \
                 "" \
                 [subst_vars {[*]\s+$inf\s+[^\r\n]*(?=\r\n).*}]]
    ...
    
    Tested on x86_64-linux and ppc64-linux.
    
    [1] https://sourceware.org/bugzilla/show_bug.cgi?id=34471
    [2] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1143513

Diff:
---
 gdb/testsuite/gdb.python/py-selected-context.exp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.python/py-selected-context.exp b/gdb/testsuite/gdb.python/py-selected-context.exp
index 28b9b456003..07ace151f26 100644
--- a/gdb/testsuite/gdb.python/py-selected-context.exp
+++ b/gdb/testsuite/gdb.python/py-selected-context.exp
@@ -46,7 +46,9 @@ proc event_regexp { inferior {thread "None"} {frame "None"}} {
 # inferior.  INF should be an inferior number, e.g. '1', '2', etc.
 proc check_inferior { inf testname } {
     gdb_test "info inferiors" \
-	"\r\n\\*\\s+[string_to_regexp $inf]\\s+\[^\r\n\]*(?=\r\n)" \
+	[multi_line \
+	     "" \
+	     [subst_vars {[*]\s+$inf\s+[^\r\n]*(?=\r\n).*}]] \
 	$testname
 }