bash: get --pretty=m<tab> completion to work with bash v4

Bash's programmable completion provides the COMP_WORDS array variable,
which holds the individual words in the current command line.  In bash
versions prior to v4 "words are split on shell metacharacters as the
shell parser would separate them" (quote from bash v3.2.48's man
page).  This behavior has changed with bash v4, and the command line
"is split into words as readline would split it, using COMP_WORDBREAKS
as" "the set of characters that the readline library treats as word
separators" (quote from bash v4's man page).

Since COMP_WORDBREAKS contains the characters : and = by default, this
behavior change in bash affects git's completion script.  For example,
before bash 4, running

	$ git log --pretty=m <tab><tab>

would give a list of pretty-printing formats starting with 'm' but now
it completes on branch names.

It would be possible to work around this by removing '=' and ':' from
COMP_WORDBREAKS, but as noticed in v1.5.6.4~9^2 (bash completion:
Resolve git show ref:path<tab> losing ref: portion, 2008-07-15), that
would break *other* completion scripts.  The bash-completion library
includes a better workaround: the _get_comp_words_by_ref function
re-assembles a copy of COMP_WORDS, excluding a collection of word
separators of the caller's choice.  Use it.

As a bonus, this also improves behavior when tab is pressed with the
cursor in the middle of a word.

To avoid breaking setups with the bash-completion library not already
loaded, if the _get_comp_words_by_ref function is not defined then a
shim that just reads COMP_WORDS will be used instead (no change from
the current behavior in that case).

Signed-off-by: Peter van der Does <peter@avirtualhome.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Explained-by: SZEDER Gábor <szeder@ira.uka.de>

1 files changed, 160 insertions, 76 deletions

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 82e660968..68b68d0c7 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -321,11 +321,39 @@ __gitcomp_1 ()
 	done
 }
 
+if ! type _get_comp_words_by_ref >/dev/null 2>&1; then
+_get_comp_words_by_ref ()
+{
+	while [ $# -gt 0 ]; do
+		case "$1" in
+		cur)
+			cur=${COMP_WORDS[COMP_CWORD]}
+			;;
+		prev)
+			prev=${COMP_WORDS[COMP_CWORD-1]}
+			;;
+		words)
+			words=("${COMP_WORDS[@]}")
+			;;
+		cword)
+			cword=$COMP_CWORD
+			;;
+		-n)
+			# assume COMP_WORDBREAKS is already set sanely
+			shift
+			;;
+		esac
+		shift
+	done
+}
+fi
+
 # __gitcomp accepts 1, 2, 3, or 4 arguments
 # generates completion reply with compgen
 __gitcomp ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	if [ $# -gt 2 ]; then
 		cur="$3"
 	fi
@@ -384,7 +412,8 @@ __git_tags ()
 __git_refs ()
 {
 	local i is_hash=y dir="$(__gitdir "${1-}")"
-	local cur="${COMP_WORDS[COMP_CWORD]}" format refs
+	local cur format refs
+	_get_comp_words_by_ref -n =: cur
 	if [ -d "$dir" ]; then
 		case "$cur" in
 		refs|refs/*)
@@ -482,7 +511,8 @@ __git_compute_merge_strategies ()
 
 __git_complete_file ()
 {
-	local pfx ls ref cur="${COMP_WORDS[COMP_CWORD]}"
+	local pfx ls ref cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	?*:*)
 		ref="${cur%%:*}"
@@ -530,7 +560,8 @@ __git_complete_file ()
 
 __git_complete_revlist ()
 {
-	local pfx cur="${COMP_WORDS[COMP_CWORD]}"
+	local pfx cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	*...*)
 		pfx="${cur%...*}..."
@@ -550,11 +581,12 @@ __git_complete_revlist ()
 
 __git_complete_remote_or_refspec ()
 {
-	local cmd="${COMP_WORDS[1]}"
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur words cword
+	_get_comp_words_by_ref -n =: cur words cword
+	local cmd="${words[1]}"
 	local i c=2 remote="" pfx="" lhs=1 no_complete_refspec=0
-	while [ $c -lt $COMP_CWORD ]; do
-		i="${COMP_WORDS[c]}"
+	while [ $c -lt $cword ]; do
+		i="${words[c]}"
 		case "$i" in
 		--mirror) [ "$cmd" = "push" ] && no_complete_refspec=1 ;;
 		--all)
@@ -622,13 +654,14 @@ __git_complete_remote_or_refspec ()
 
 __git_complete_strategy ()
 {
+	local cur prev
+	_get_comp_words_by_ref -n =: cur prev
 	__git_compute_merge_strategies
-	case "${COMP_WORDS[COMP_CWORD-1]}" in
+	case "$prev" in
 	-s|--strategy)
 		__gitcomp "$__git_merge_strategies"
 		return 0
 	esac
-	local cur="${COMP_WORDS[COMP_CWORD]}"
 	case "$cur" in
 	--strategy=*)
 		__gitcomp "$__git_merge_strategies" "" "${cur##--strategy=}"
@@ -788,10 +821,10 @@ __git_aliased_command ()
 # __git_find_on_cmdline requires 1 argument
 __git_find_on_cmdline ()
 {
-	local word subcommand c=1
-
-	while [ $c -lt $COMP_CWORD ]; do
-		word="${COMP_WORDS[c]}"
+	local word subcommand c=1 words cword
+	_get_comp_words_by_ref -n =: words cword
+	while [ $c -lt $cword ]; do
+		word="${words[c]}"
 		for subcommand in $1; do
 			if [ "$subcommand" = "$word" ]; then
 				echo "$subcommand"
@@ -804,9 +837,10 @@ __git_find_on_cmdline ()
 
 __git_has_doubledash ()
 {
-	local c=1
-	while [ $c -lt $COMP_CWORD ]; do
-		if [ "--" = "${COMP_WORDS[c]}" ]; then
+	local c=1 words cword
+	_get_comp_words_by_ref -n =: words cword
+	while [ $c -lt $cword ]; do
+		if [ "--" = "${words[c]}" ]; then
 			return 0
 		fi
 		c=$((++c))
@@ -818,7 +852,8 @@ __git_whitespacelist="nowarn warn error error-all fix"
 
 _git_am ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}" dir="$(__gitdir)"
+	local cur dir="$(__gitdir)"
+	_get_comp_words_by_ref -n =: cur
 	if [ -d "$dir"/rebase-apply ]; then
 		__gitcomp "--skip --continue --resolved --abort"
 		return
@@ -842,7 +877,8 @@ _git_am ()
 
 _git_apply ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--whitespace=*)
 		__gitcomp "$__git_whitespacelist" "" "${cur##--whitespace=}"
@@ -865,7 +901,8 @@ _git_add ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -879,7 +916,8 @@ _git_add ()
 
 _git_archive ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--format=*)
 		__gitcomp "$(git archive --list)" "" "${cur##--format=}"
@@ -923,10 +961,11 @@ _git_bisect ()
 
 _git_branch ()
 {
-	local i c=1 only_local_ref="n" has_r="n"
+	local i c=1 only_local_ref="n" has_r="n" cur words cword
 
-	while [ $c -lt $COMP_CWORD ]; do
-		i="${COMP_WORDS[c]}"
+	_get_comp_words_by_ref -n =: cur words cword
+	while [ $c -lt $cword ]; do
+		i="${words[c]}"
 		case "$i" in
 		-d|-m)	only_local_ref="y" ;;
 		-r)	has_r="y" ;;
@@ -934,7 +973,7 @@ _git_branch ()
 		c=$((++c))
 	done
 
-	case "${COMP_WORDS[COMP_CWORD]}" in
+	case "$cur" in
 	--*)
 		__gitcomp "
 			--color --no-color --verbose --abbrev= --no-abbrev
@@ -954,8 +993,10 @@ _git_branch ()
 
 _git_bundle ()
 {
-	local cmd="${COMP_WORDS[2]}"
-	case "$COMP_CWORD" in
+	local words cword
+	_get_comp_words_by_ref -n =: words cword
+	local cmd="${words[2]}"
+	case "$cword" in
 	2)
 		__gitcomp "create list-heads verify unbundle"
 		;;
@@ -976,7 +1017,8 @@ _git_checkout ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--conflict=*)
 		__gitcomp "diff3 merge" "" "${cur##--conflict=}"
@@ -1000,7 +1042,8 @@ _git_cherry ()
 
 _git_cherry_pick ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--edit --no-commit"
@@ -1015,7 +1058,8 @@ _git_clean ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--dry-run --quiet"
@@ -1027,7 +1071,8 @@ _git_clean ()
 
 _git_clone ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -1054,7 +1099,8 @@ _git_commit ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--cleanup=*)
 		__gitcomp "default strip verbatim whitespace
@@ -1089,7 +1135,8 @@ _git_commit ()
 
 _git_describe ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -1121,7 +1168,8 @@ _git_diff ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--cached --staged --pickaxe-all --pickaxe-regex
@@ -1142,7 +1190,8 @@ _git_difftool ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--tool=*)
 		__gitcomp "$__git_mergetools_common kompare" "" "${cur##--tool=}"
@@ -1167,7 +1216,8 @@ __git_fetch_options="
 
 _git_fetch ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "$__git_fetch_options"
@@ -1179,7 +1229,8 @@ _git_fetch ()
 
 _git_format_patch ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--thread=*)
 		__gitcomp "
@@ -1211,7 +1262,8 @@ _git_format_patch ()
 
 _git_fsck ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -1226,7 +1278,8 @@ _git_fsck ()
 
 _git_gc ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--prune --aggressive"
@@ -1245,7 +1298,8 @@ _git_grep ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -1268,7 +1322,8 @@ _git_grep ()
 
 _git_help ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--all --info --man --web"
@@ -1286,7 +1341,8 @@ _git_help ()
 
 _git_init ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--shared=*)
 		__gitcomp "
@@ -1306,7 +1362,8 @@ _git_ls_files ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--cached --deleted --modified --others --ignored
@@ -1360,12 +1417,13 @@ _git_log ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
 	local g="$(git rev-parse --git-dir 2>/dev/null)"
 	local merge=""
 	if [ -f "$g/MERGE_HEAD" ]; then
 		merge="--merge"
 	fi
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--pretty=*)
 		__gitcomp "$__git_log_pretty_formats
@@ -1419,7 +1477,8 @@ _git_merge ()
 {
 	__git_complete_strategy && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "$__git_merge_options"
@@ -1430,7 +1489,8 @@ _git_merge ()
 
 _git_mergetool ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--tool=*)
 		__gitcomp "$__git_mergetools_common tortoisemerge" "" "${cur##--tool=}"
@@ -1451,7 +1511,8 @@ _git_merge_base ()
 
 _git_mv ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--dry-run"
@@ -1469,12 +1530,14 @@ _git_name_rev ()
 _git_notes ()
 {
 	local subcommands="edit show"
+	local words cword
+	_get_comp_words_by_ref -n =: words cword
 	if [ -z "$(__git_find_on_cmdline "$subcommands")" ]; then
 		__gitcomp "$subcommands"
 		return
 	fi
 
-	case "${COMP_WORDS[COMP_CWORD-1]}" in
+	case "${words[cword-1]}" in
 	-m|-F)
 		COMPREPLY=()
 		;;
@@ -1488,7 +1551,8 @@ _git_pull ()
 {
 	__git_complete_strategy && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -1504,8 +1568,9 @@ _git_pull ()
 
 _git_push ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
-	case "${COMP_WORDS[COMP_CWORD-1]}" in
+	local cur prev
+	_get_comp_words_by_ref -n =: cur prev
+	case "$prev" in
 	--repo)
 		__gitcomp "$(__git_remotes)"
 		return
@@ -1528,7 +1593,9 @@ _git_push ()
 
 _git_rebase ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}" dir="$(__gitdir)"
+	local dir="$(__gitdir)"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	if [ -d "$dir"/rebase-apply ] || [ -d "$dir"/rebase-merge ]; then
 		__gitcomp "--continue --skip --abort"
 		return
@@ -1558,7 +1625,8 @@ __git_send_email_suppresscc_options="author self cc bodycc sob cccmd body all"
 
 _git_send_email ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--confirm=*)
 		__gitcomp "
@@ -1600,9 +1668,11 @@ _git_stage ()
 
 __git_config_get_set_variables ()
 {
-	local prevword word config_file= c=$COMP_CWORD
+	local words cword
+	_get_comp_words_by_ref -n =: words cword
+	local prevword word config_file= c=$cword
 	while [ $c -gt 1 ]; do
-		word="${COMP_WORDS[c]}"
+		word="${words[c]}"
 		case "$word" in
 		--global|--system|--file=*)
 			config_file="$word"
@@ -1630,9 +1700,9 @@ __git_config_get_set_variables ()
 
 _git_config ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
-	local prv="${COMP_WORDS[COMP_CWORD-1]}"
-	case "$prv" in
+	local cur prev
+	_get_comp_words_by_ref -n =: cur prev
+	case "$prev" in
 	branch.*.remote)
 		__gitcomp "$(__git_remotes)"
 		return
@@ -1642,13 +1712,13 @@ _git_config ()
 		return
 		;;
 	remote.*.fetch)
-		local remote="${prv#remote.}"
+		local remote="${prev#remote.}"
 		remote="${remote%.fetch}"
 		__gitcomp "$(__git_refs_remotes "$remote")"
 		return
 		;;
 	remote.*.push)
-		local remote="${prv#remote.}"
+		local remote="${prev#remote.}"
 		remote="${remote%.push}"
 		__gitcomp "$(git --git-dir="$(__gitdir)" \
 			for-each-ref --format='%(refname):%(refname)' \
@@ -2039,7 +2109,8 @@ _git_reset ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--merge --mixed --hard --soft --patch"
@@ -2051,7 +2122,8 @@ _git_reset ()
 
 _git_revert ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--edit --mainline --no-edit --no-commit --signoff"
@@ -2065,7 +2137,8 @@ _git_rm ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "--cached --dry-run --ignore-unmatch --quiet"
@@ -2079,7 +2152,8 @@ _git_shortlog ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -2097,7 +2171,8 @@ _git_show ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--pretty=*)
 		__gitcomp "$__git_log_pretty_formats
@@ -2121,7 +2196,8 @@ _git_show ()
 
 _git_show_branch ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "
@@ -2138,7 +2214,8 @@ _git_show_branch ()
 
 _git_stash ()
 {
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
+	_get_comp_words_by_ref -n =: cur
 	local save_opts='--keep-index --no-keep-index --quiet --patch'
 	local subcommands='save list show apply clear drop pop create branch'
 	local subcommand="$(__git_find_on_cmdline "$subcommands")"
@@ -2183,7 +2260,8 @@ _git_submodule ()
 
 	local subcommands="add status init update summary foreach sync"
 	if [ -z "$(__git_find_on_cmdline "$subcommands")" ]; then
-		local cur="${COMP_WORDS[COMP_CWORD]}"
+		local cur
+		_get_comp_words_by_ref -n =: cur
 		case "$cur" in
 		--*)
 			__gitcomp "--quiet --cached"
@@ -2227,7 +2305,8 @@ _git_svn ()
 			--edit --rmdir --find-copies-harder --copy-similarity=
 			"
 
-		local cur="${COMP_WORDS[COMP_CWORD]}"
+		local cur
+		_get_comp_words_by_ref -n =: cur
 		case "$subcommand,$cur" in
 		fetch,--*)
 			__gitcomp "--revision= --fetch-all $fc_opts"
@@ -2299,8 +2378,10 @@ _git_svn ()
 _git_tag ()
 {
 	local i c=1 f=0
-	while [ $c -lt $COMP_CWORD ]; do
-		i="${COMP_WORDS[c]}"
+	local words cword prev
+	_get_comp_words_by_ref -n =: words cword prev
+	while [ $c -lt $cword ]; do
+		i="${words[c]}"
 		case "$i" in
 		-d|-v)
 			__gitcomp "$(__git_tags)"
@@ -2313,7 +2394,7 @@ _git_tag ()
 		c=$((++c))
 	done
 
-	case "${COMP_WORDS[COMP_CWORD-1]}" in
+	case "$prev" in
 	-m|-F)
 		COMPREPLY=()
 		;;
@@ -2339,8 +2420,10 @@ _git ()
 {
 	local i c=1 command __git_dir
 
-	while [ $c -lt $COMP_CWORD ]; do
-		i="${COMP_WORDS[c]}"
+	local cur words cword
+	_get_comp_words_by_ref -n =: cur words cword
+	while [ $c -lt $cword ]; do
+		i="${words[c]}"
 		case "$i" in
 		--git-dir=*) __git_dir="${i#--git-dir=}" ;;
 		--bare)      __git_dir="." ;;
@@ -2352,7 +2435,7 @@ _git ()
 	done
 
 	if [ -z "$command" ]; then
-		case "${COMP_WORDS[COMP_CWORD]}" in
+		case "$cur" in
 		--*)   __gitcomp "
 			--paginate
 			--no-pager
@@ -2385,12 +2468,13 @@ _gitk ()
 {
 	__git_has_doubledash && return
 
-	local cur="${COMP_WORDS[COMP_CWORD]}"
+	local cur
 	local g="$(__gitdir)"
 	local merge=""
 	if [ -f "$g/MERGE_HEAD" ]; then
 		merge="--merge"
 	fi
+	_get_comp_words_by_ref -n =: cur
 	case "$cur" in
 	--*)
 		__gitcomp "