problems using trap 'eval `resize`' SIGWINCH

[eddy]

Configuration Information [Automatically generated, do not change]:
Machine: i386
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='i386' 
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i386-pc-linux-gnu' 
-DCONF_VENDOR='pc' -DSHELL -DHAVE_CONFIG_H  -D_FILE_OFFSET_BITS=64  -I. 
-I/usr/include -I/home/swt/doko/export/packages/bash/bash-2.05 
-I/home/swt/doko/export/packages/bash/bash-2.05/include 
-I/home/swt/doko/export/packages/bash/bash-2.05/lib -I/usr/include -g -O2
uname output: Linux vortex 2.2.19 #1 Thu Apr 19 22:35:28 EST 2001 i686 unknown
Machine Type: i386-pc-linux-gnu

Bash Version: 2.05
Patch Level: 0
Release Status: release

Description:
        I have, for years, been trapping SIGWINCH with 'eval `resize`'
        and it worked fine: i.e. I never noticed it was happening, but
        COLUMNS and LINES always had sensible values (they still do,
        fortunately).

        Lately, I've been having the problem illustrated below.  After
        a window resize operation, bash is in some weird state where
        it's buffering up my input as if for a command, but not acting
        on it until I ^D or type a lone semi-colon.  After the first
        line of input, it (does nothing and) comes back with $PS1;
        after the second, it (does nothing and) comes back with $PS2.
        Resizing after first input but before second puts the command
        typed into the command history and resets our PS number.

        Interaction with up-arrow while in the mangled state is weirder.

        Using kill -WINCH $$ doesn't activate the problem, so I can
        only reproduce it inside an xterm.  Turning off trapping of
        WINCH removes the problem; trapping it with another command
        reinstates the problem.  Hitting return after a resize
        suppresses the problem (i.e. is a work-around; so severity of
        this bug is `minor', I guess).

        I'm running bash inside an xterm under fvwm2 on debian.
        I'm totally confused by this behaviour !

Repeat-By:
eddy:vortex> trap 'eval `resize`' SIGWINCH
        # resize window, by clicking the `maximise vertical' button,
eddy:vortex> clear
        # notice that this hasn't happened so try again
eddy:vortex> clear
:> 
        # perplexed, hit return; $PS2 appears again;
        # being puzzled, type ^D
:> bash: syntax error: unexpected end of file
        # hit up-arrow (but no return)
eddy:vortex> clear; clear; 
        # ^U that and type
eddy:vortex> resize
COLUMNS=80;
LINES=24;
export COLUMNS LINES;
eddy:vortex> echo $PS1
\u:\h>
eddy:vortex> echo $PS2
:>
eddy:vortex> echo $IGNOREEOF
1
eddy:vortex> clear
        # OK, clear worked this time;
        # do a resize by dragging window corner, then type
eddy:vortex> clear
eddy:vortex> clear
:> clear
:> clear
:> clear
:> clear
:> clear
:> ;
bash: syntax error near unexpected token `;'
        # $PS1 re-appears; hit up-arrow (but no return)
eddy:vortex> clear; clear; clear; clear; clear; clear; clear; ;
        # ^U, type
eddy:vortex> clear
        # window clears, $PS1 re-appears; resize window, type ^D
eddy:vortex> Use "exit" to leave the shell.
        # $PS1 re-appears; type clear
eddy:vortex> clear
        # window clears, $PS1 re-appears; resize, type ;
eddy:vortex> ;
bash: syntax error near unexpected token `;'
eddy:vortex> clear
        # window clears, $PS1 re-appears; resize; type
eddy:vortex> echo hello
        # nothing echoed; hit up-arrow and return
eddy:vortex> echo hello
        # nothing echoed; hit up-arrow and return
:> echo hello; echo hello
        # nothing echoed; hit up-arrow and return
:> echo hello; echo hello; echo hello; echo hello
        # that's quite enough of that; ^D the next $PS2
:> bash: syntax error: unexpected end of file
eddy:vortex> kill -WINCH $$
eddy:vortex> clear
        # window clears !
eddy:vortex> trap '' WINCH
        # resize window
eddy:vortex> clear
        # window clears !
eddy:vortex> trap 'echo mumble' WINCH
        # maximise vertical
eddy:vortex> mumble
        # unmaximise vertical
eddy:vortex> mumble
        # that's output we've seen emitted; now type
clear
        # and type it again
eddy:vortex> clear
        # and again
:> clear
        # so hit up-arrow and return
:> clear; clear; clear
        # so ^D the next $PS2
:> bash: syntax error: unexpected end of file
eddy:vortex> clear
        # window clears
eddy:vortex> trap 'eval `resize`' WINCH
        # resize, hit return
eddy:vortex>
        # nothing happened, sensibly enough; type
eddy:vortex> clear
        # window clears !
eddy:vortex> echo hello
hello
        # maximise vertical, type
eddy:vortex> clear
        # didn't do it; unmaximise vertical; up-arrow and return
eddy:vortex> clear
        # didn't do it; maximise, up;
eddy:vortex> clear
        # didn't; unmax, up;
eddy:vortex> clear
        # didn't; max, up;
eddy:vortex> clear
        # didn't; up-arrow (no return)
:> clear; clear
        # up-arrow again (still no return)
:> clear
        # same for next several, until
:> echo hello
        # so hit return this time; get $PS2, type ^D
:> bash: syntax error: unexpected end of file
        # get $PS1, type up-arrow (no return)
eddy:vortex> clear; clear; echo hello; 
        # further up-arrows reveal the
        # sequence of lone clears preceded by echo.