Re: [PATCH] [gdb/testsuite, Tcl 9] Fix EILSEQ problems for UTF8 related tests

[Tom de Vries <tdevries@suse.de>]

On 5/25/26 7:14 AM, Kevin Buettner wrote:
> On Fedora 44 and Rawhide (Fedora 45), these tests...
> 
>    gdb.ada/non-ascii-utf-8.exp
>    gdb.base/utf8-identifiers.exp
>    gdb.rust/unicode.exp
> 
> ...all die due to these errors:
> 
>    Running ...gdb/testsuite/gdb.base/utf8-identifiers.exp ...
>    ERROR: tcl error sourcing .../gdb/testsuite/gdb.base/utf8-identifiers.exp.
>    ERROR: tcl error code POSIX EILSEQ {invalid or incomplete multibyte or wide character}
>    error writing "file6": invalid or incomplete multibyte or wide character
>    ...
> 
> (I've shortened some of the pathnames for brevity.)
> 
> These Fedora systems are using Tcl 9 and also an updated version of
> dejagnu with this change applied:
> 
>    * Thu Apr 16 2026 Jakub Jelinek <jakub@redhat.com> - 1:1.6.3-17
>    - Apply full set of Tcl 9 compatibility fixes from upstream PR80674 branch
>      (#2448542)
> 
> That runtest change is responsible for the POSIX EILSEQ errors on
> machines with that change.  The change to runtest causing the change
> in behavior for GDB is the addition of these lines near the top of
> the runtest script:
> 
>    # Ensure that DejaGnu will be run in the POSIX locale
>    LC_ALL=C
>    export LC_ALL
> 
> TCL 8 used a permissive encoding strategy: bytes that could not be
> represented in the current encoding were silently mangled or
> substituted.  TCL 9 changed this default to a strict profile, which
> means that any attempt to write a character that cannot be expressed
> in the channel's encoding raises a POSIX EILSEQ error ("invalid or
> incomplete multibyte or wide character").
> 
> So, together, this Tcl 9 behavior combined with the dejagnu change
> to runtest causes the EILSEQ error for the tests mentioned earlier.
> 
> Fix it by using "fconfigure $handle -encoding utf-8 -profile replace"
> in proc spawn_capture_tty_name, and proc gdb_stdin_log_init.  Also,
> the open_logs wrapper has been changed to invoke fconfigure using only
> "-encoding utf-8".  Testing showed that "-profile replace" wasn't
> necessary there.
> 

Hi Kevin,

this LGTM, so:

Reviewed-By: Tom de Vries <tdevries@suse.de>

I also reviewed this using Claude code, and there were two notes:
- using catch for one fconfigure, but not the other two.
- it might be a good idea to add a comment in open_logs to make it
   explicit that unlike elsewhere, "-profile replace" isn't used.

Thanks,
- Tom

> Tested on Fedora 28 (Tcl 8.6.8), Fedora 43 (Tcl 9.0.2 / 8.6.16; expect
> uses 8.6.16), Fedora 44 (Tcl 9.0.2 / 8.6.17; expect uses 9.0.2), and
> Rawhide / Fedora 45 (Tcl 9.0.3 / 8.6.18; expect uses 9.0.3).
> ---
>   gdb/testsuite/lib/gdb.exp | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
> 
> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
> index 28709004570..52e4be9122d 100644
> --- a/gdb/testsuite/lib/gdb.exp
> +++ b/gdb/testsuite/lib/gdb.exp
> @@ -166,6 +166,27 @@ proc load_lib { file } {
>       return $result
>   }
>   
> +# Tcl 9.0 changed the default channel encoding profile to "strict".  When
> +# runtest sets LC_ALL=C the system encoding is iso8859-1, so file channels
> +# opened by DejaGNU (gdb.sum, gdb.log) and spawn channels (for GDB and
> +# subprocesses) default to iso8859-1 with strict profile.  Writing
> +# non-Latin-1 characters in test names then raises EILSEQ, and sending them
> +# to GDB truncates the command at the unrepresentable character.
> +#
> +# Fix this by:
> +# 1. Overriding open_logs to reconfigure gdb.sum to utf-8 after DejaGNU
> +#    opens it with the system (iso8859-1) encoding.
> +# 2. Reconfiguring each new spawn channel to utf-8 in
> +#    spawn_capture_tty_name, which wraps every spawn call.
> +# 3. Reconfiguring gdb.in to utf-8 in gdb_stdin_log_init.
> +
> +rename open_logs saved_open_logs
> +proc open_logs {} {
> +    saved_open_logs
> +    global sum_file
> +    fconfigure $sum_file -encoding utf-8
> +}
> +
>   load_lib libgloss.exp
>   load_lib cache.exp
>   load_lib gdb-utils.exp
> @@ -2633,6 +2654,7 @@ proc gdb_file_cmd { arg {kill_flag 1} } {
>   proc spawn_capture_tty_name { args } {
>       set result [uplevel builtin_spawn $args]
>       upvar spawn_out spawn_out
> +    upvar spawn_id spawn_id
>       if { [info exists spawn_out(slave,name)] } {
>   	set ::last_spawn_tty_name $spawn_out(slave,name)
>       } else {
> @@ -2648,6 +2670,12 @@ proc spawn_capture_tty_name { args } {
>   	# use -nocomplain here we would otherwise get an error.
>   	unset -nocomplain ::last_spawn_tty_name
>       }
> +    # Tcl 9.0 defaults spawn channels to iso8859-1/strict, which raises
> +    # EILSEQ when non-Latin-1 characters (e.g. function names with UTF-8
> +    # letters) are written to or read from the channel.  Use utf-8 instead.
> +    if {[tcl_version_at_least 9 0 0]} {
> +	catch {fconfigure $spawn_id -encoding utf-8 -profile replace}
> +    }
>       return $result
>   }
>   
> @@ -10419,6 +10447,11 @@ proc gdb_stdin_log_init { } {
>       set logfile [standard_output_file_with_gdb_instance gdb.in]
>       set in_file [open $logfile w]
>   
> +    if {[tcl_version_at_least 9 0 0]} {
> +	# Tcl 9 strict profile: gdb.in must accept UTF-8 command strings.
> +	fconfigure $in_file -encoding utf-8 -profile replace
> +    }
> +
>       verbose -log ""
>       verbose -log "Starting logfile: $logfile"
>       verbose -log ""