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

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.

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).

With regard to the Bug noted below, I haven't been able to reproduce
the failures in gdb.ada/lazy-string.exp, but I've been informed that
this commit fixes it.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=34146
Reviewed-By: Tom de Vries <tdevries@suse.de>

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index cd59ada7e51a4bd1483874c0fc04d79acc7b7d49..96ef9e952a8c635e6296503db58151f07ddc5c45 100644 (file)
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -166,6 +166,35 @@ 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.  Only
+#    "-encoding utf-8" is needed here, not "-profile replace".  The
+#    test names written to gdb.sum are Unicode strings, and since
+#    UTF-8 can represent every Unicode character, the encode
+#    operation cannot fail.  This use of "fconfigure" lacks a Tcl
+#    version guard since "-encoding utf-8" works in both Tcl 8 and
+#    Tcl 9.  (Use of "-profile replace" requires a guard, as that
+#    option did not exist before Tcl 9.)
+# 2. Reconfiguring each new spawn channel to UTF-8 and to also use
+#    "-profile replace" in spawn_capture_tty_name, which wraps every
+#    spawn call.
+# 3. Likewise for gdb_stdin_log_init.
+
+rename open_logs saved_open_logs
+proc open_logs {} {
+    saved_open_logs
+    fconfigure $::sum_file -encoding utf-8
+}
+
 load_lib libgloss.exp
 load_lib cache.exp
 load_lib gdb-utils.exp
@@ -2633,6 +2662,7 @@ 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 +2678,21 @@ 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. identifiers
+    # with UTF-8 letters) are written to or read from the channel.
+    # Use utf-8 instead.
+    #
+    # "catch" is used here because, unlike the other sites in this
+    # file where fconfigure is used, this use of fconfigure could
+    # attempt to modify channels which do not support these options.
+    # Those other sites use "fconfigure" on recently opened files
+    # where it will almost certainly work.  (And, for those other sites,
+    # if it doesn't work, we want to be notified of that fact via the
+    # normal Tcl error reporting mechanisms.)
+    if {[tcl_version_at_least 9 0 0]} {
+       catch {fconfigure $spawn_id -encoding utf-8 -profile replace}
+    }
     return $result
 }
 
@@ -10527,6 +10572,11 @@ 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 ""