Fix issues with LASTWIDGET caused by async suggestions

There are a number of widgets that rely on LASTWIDGET so that they can
chain their behavior together on subsequent invocations. When a
suggestion was fetched asynchronously, the widget showing the suggestion
would overwrite LASTWIDGET and break these widgets that rely on it.
Relatively recently, a flag was added to the `zle` builtin to opt out of
setting LASTWIDGET when calling a widget. We can use that flag to avoid
setting LASTWIDGET when displaying suggestions that were fetched
asynchronously.

src/async.zsh

@@ -15,39 +15,40 @@ _zsh_autosuggest_async_request() {
 		zle -F $_ZSH_AUTOSUGGEST_ASYNC_FD
 
 		# We won't know the pid unless the user has zsh/system module installed
-		if (( _ZSH_AUTOSUGGEST_CHILD_PID )); then
-			kill -TERM -- $_ZSH_AUTOSUGGEST_CHILD_PID 2>/dev/null
+		if [[ -n "$_ZSH_AUTOSUGGEST_CHILD_PID" ]]; then
+			# Zsh will make a new process group for the child process only if job
+			# control is enabled (MONITOR option)
+			if [[ -o MONITOR ]]; then
+				# Send the signal to the process group to kill any processes that may
+				# have been forked by the suggestion strategy
+				kill -TERM -$_ZSH_AUTOSUGGEST_CHILD_PID 2>/dev/null
+			else
+				# Kill just the child process since it wasn't placed in a new process
+				# group. If the suggestion strategy forked any child processes they may
+				# be orphaned and left behind.
+				kill -TERM $_ZSH_AUTOSUGGEST_CHILD_PID 2>/dev/null
+			fi
 		fi
 	fi
 
 	# Fork a process to fetch a suggestion and open a pipe to read from it
 	exec {_ZSH_AUTOSUGGEST_ASYNC_FD}< <(
-		# Tell parent process our pid if we can
-		echo ${sysparams[pid]:-}
+		# Tell parent process our pid
+		echo $sysparams[pid]
 
 		# Fetch and print the suggestion
 		local suggestion
 		_zsh_autosuggest_fetch_suggestion "$1"
-		echo -nE - "$suggestion"
+		echo -nE "$suggestion"
 	)
 
 	# There's a weird bug here where ^C stops working unless we force a fork
 	# See https://github.com/zsh-users/zsh-autosuggestions/issues/364
-	autoload -Uz is-at-least
 	is-at-least 5.8 || command true
 
 	# Read the pid from the child process
 	read _ZSH_AUTOSUGGEST_CHILD_PID <&$_ZSH_AUTOSUGGEST_ASYNC_FD
 
-	# Zsh will make a new process group for the child process only if job
-	# control is enabled (MONITOR option)
-	if [[ -o MONITOR ]]; then
-		# If we need to kill the background process in the future, we'll send
-		# SIGTERM to the process group to kill any processes that may have been
-		# forked by the suggestion strategy
-		_ZSH_AUTOSUGGEST_CHILD_PID=${_ZSH_AUTOSUGGEST_CHILD_PID:+-$_ZSH_AUTOSUGGEST_CHILD_PID}
-	fi
-
 	# When the fd is readable, call the response handler
 	zle -F "$_ZSH_AUTOSUGGEST_ASYNC_FD" _zsh_autosuggest_async_response
 }
@@ -58,20 +59,28 @@ _zsh_autosuggest_async_request() {
 _zsh_autosuggest_async_response() {
 	emulate -L zsh
 
-	typeset -g _ZSH_AUTOSUGGEST_ASYNC_FD _ZSH_AUTOSUGGEST_CHILD_PID
 	local suggestion
 
-	if [[ $# == 1 || "$2" == "hup" ]]; then
+	if [[ -z "$2" || "$2" == "hup" ]]; then
 		# Read everything from the fd and give it as a suggestion
 		IFS='' read -rd '' -u $1 suggestion
-		zle autosuggest-suggest -- "$suggestion"
+		_zsh_autosuggest_async_suggest "$suggestion"
 
 		# Close the fd
 		exec {1}<&-
-		_ZSH_AUTOSUGGEST_ASYNC_FD=
-		_ZSH_AUTOSUGGEST_ASYNC_PID=
 	fi
 
 	# Always remove the handler
-	zle -F $1
+	zle -F "$1"
+}
+
+_zsh_autosuggest_async_suggest() {
+	# Before 5.9, async suggestions break widgets that rely on LASTWIDGET
+	# such as copy-earlier-word and {up,down}-line-or-beginning-search. In
+	# 5.9, a flag was added to `zle` that will skip setting LASTWIDGET so
+	# that those widgets that depend on it will continue to work
+	# See https://www.zsh.org/mla/workers/2020/msg00824.html
+	local nolast
+	is-at-least 5.9 && nolast=supported
+	zle autosuggest-suggest ${=nolast:+-f nolast} -- "$1"
 }

zsh-autosuggestions.zsh

@@ -770,39 +770,40 @@ _zsh_autosuggest_async_request() {
 		zle -F $_ZSH_AUTOSUGGEST_ASYNC_FD
 
 		# We won't know the pid unless the user has zsh/system module installed
-		if (( _ZSH_AUTOSUGGEST_CHILD_PID )); then
-			kill -TERM -- $_ZSH_AUTOSUGGEST_CHILD_PID 2>/dev/null
+		if [[ -n "$_ZSH_AUTOSUGGEST_CHILD_PID" ]]; then
+			# Zsh will make a new process group for the child process only if job
+			# control is enabled (MONITOR option)
+			if [[ -o MONITOR ]]; then
+				# Send the signal to the process group to kill any processes that may
+				# have been forked by the suggestion strategy
+				kill -TERM -$_ZSH_AUTOSUGGEST_CHILD_PID 2>/dev/null
+			else
+				# Kill just the child process since it wasn't placed in a new process
+				# group. If the suggestion strategy forked any child processes they may
+				# be orphaned and left behind.
+				kill -TERM $_ZSH_AUTOSUGGEST_CHILD_PID 2>/dev/null
+			fi
 		fi
 	fi
 
 	# Fork a process to fetch a suggestion and open a pipe to read from it
 	exec {_ZSH_AUTOSUGGEST_ASYNC_FD}< <(
-		# Tell parent process our pid if we can
-		echo ${sysparams[pid]:-}
+		# Tell parent process our pid
+		echo $sysparams[pid]
 
 		# Fetch and print the suggestion
 		local suggestion
 		_zsh_autosuggest_fetch_suggestion "$1"
-		echo -nE - "$suggestion"
+		echo -nE "$suggestion"
 	)
 
 	# There's a weird bug here where ^C stops working unless we force a fork
 	# See https://github.com/zsh-users/zsh-autosuggestions/issues/364
-	autoload -Uz is-at-least
 	is-at-least 5.8 || command true
 
 	# Read the pid from the child process
 	read _ZSH_AUTOSUGGEST_CHILD_PID <&$_ZSH_AUTOSUGGEST_ASYNC_FD
 
-	# Zsh will make a new process group for the child process only if job
-	# control is enabled (MONITOR option)
-	if [[ -o MONITOR ]]; then
-		# If we need to kill the background process in the future, we'll send
-		# SIGTERM to the process group to kill any processes that may have been
-		# forked by the suggestion strategy
-		_ZSH_AUTOSUGGEST_CHILD_PID=${_ZSH_AUTOSUGGEST_CHILD_PID:+-$_ZSH_AUTOSUGGEST_CHILD_PID}
-	fi
-
 	# When the fd is readable, call the response handler
 	zle -F "$_ZSH_AUTOSUGGEST_ASYNC_FD" _zsh_autosuggest_async_response
 }
@@ -813,22 +814,30 @@ _zsh_autosuggest_async_request() {
 _zsh_autosuggest_async_response() {
 	emulate -L zsh
 
-	typeset -g _ZSH_AUTOSUGGEST_ASYNC_FD _ZSH_AUTOSUGGEST_CHILD_PID
 	local suggestion
 
-	if [[ $# == 1 || "$2" == "hup" ]]; then
+	if [[ -z "$2" || "$2" == "hup" ]]; then
 		# Read everything from the fd and give it as a suggestion
 		IFS='' read -rd '' -u $1 suggestion
-		zle autosuggest-suggest -- "$suggestion"
+		_zsh_autosuggest_async_suggest "$suggestion"
 
 		# Close the fd
 		exec {1}<&-
-		_ZSH_AUTOSUGGEST_ASYNC_FD=
-		_ZSH_AUTOSUGGEST_ASYNC_PID=
 	fi
 
 	# Always remove the handler
-	zle -F $1
+	zle -F "$1"
+}
+
+_zsh_autosuggest_async_suggest() {
+	# Before 5.9, async suggestions break widgets that rely on LASTWIDGET
+	# such as copy-earlier-word and {up,down}-line-or-beginning-search. In
+	# 5.9, a flag was added to `zle` that will skip setting LASTWIDGET so
+	# that those widgets that depend on it will continue to work
+	# See https://www.zsh.org/mla/workers/2020/msg00824.html
+	local nolast
+	is-at-least 5.9 && nolast=supported
+	zle autosuggest-suggest ${=nolast:+-f nolast} -- "$1"
 }
 
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