abuild, abump: use type(1) portably

abuild.in

@@ -134,7 +134,6 @@ default_sanitycheck() {
 	if [ $(echo "$pkgdesc" | wc -c) -gt 128 ]; then
 		die "pkgdesc is too long"
 	fi
-	is_function package || die "Missing package() function in APKBUILD"
 
 	if [ -n "$replaces_priority" ] \
 		&& ! echo $replaces_priority | egrep -q '^[0-9]+$'; then
@@ -240,9 +239,11 @@ default_sanitycheck() {
 
 	makedepends_has 'g++' && ! options_has toolchain && warning "g++ should not be in makedepends"
 
+	is_function package || die "Missing package() function in APKBUILD"
+
 	if ! options_has "!check" && [ -n "$REQUIRE_CHECK" ]; then
-		(unset check; . "$APKBUILD"; type check >/dev/null 2>&1) || \
-			die "Testsuites (abuild check) are required or need to be explicitly disabled!"
+		is_function check \
+			|| die "Testsuites (abuild check) are required or need to be explicitly disabled!"
 	fi
 
 	check_provides || die "provides must not contain $pkgname"
@@ -1757,9 +1758,12 @@ openrc() {
 }
 
 
-is_function() {
-	type "$1" 2>&1 | head -n 1 | egrep -q "is a (shell )?function"
-}
+is_function() (
+	unset -f "$1" >/dev/null 2>&1 || true
+	unalias "$1" >/dev/null 2>&1 || true
+	. "$APKBUILD"
+	PATH= type "$1" >/dev/null 2>&1
+)
 
 do_fakeroot() {
 	if [ -n "$FAKEROOT" ]; then

abump.in

@@ -49,8 +49,13 @@ do_bump() {
 		name=${name#*/}
 		[ "$pkgname" = "$name" ] \
 			|| die "APKBUILD has different \$pkgname for $name"
-		type package | grep -q function \
-			|| die "missing package() for $name"
+
+		(
+			unset -f package || true
+			unalias package || true
+			. "$a"
+			PATH= type package >/dev/null 2>&1
+		) || die "missing package() for $name"
 
 		cd "${a%/*}"
 		section=${PWD%/*}