1	#!/usr/bin/env bash
2	#
3	# POSIX rule about special builtins pointed at:
4	#
5	# https://www.reddit.com/r/oilshell/comments/5ykpi3/oildev_is_alive/
6
7	#### : is special and prefix assignments persist after special builtins
8	# Bash only implements it behind the posix option
9	#test -n "$BASH_VERSION" && set -o posix
10	case $SH in
11	*dash|*zsh|*osh)
12	;;
13	*)
14	set -o posix
15	;;
16	esac
17	foo=bar :
18	echo foo=$foo
19	## STDOUT:
20	foo=bar
21	## END
22	## BUG zsh STDOUT:
23	foo=
24	## END
25
26	#### readonly is special and prefix assignments persist
27	# Bash only implements it behind the posix option
28	#test -n "$BASH_VERSION" && set -o posix
29	case $SH in
30	*dash|*zsh|*osh)
31	;;
32	*)
33	set -o posix
34	;;
35	esac
36	foo=bar readonly spam=eggs
37	echo foo=$foo
38	echo spam=$spam
39
40	# should NOT be exported
41	printenv.py foo
42	printenv.py spam
43	## STDOUT:
44	foo=bar
45	spam=eggs
46	None
47	None
48	## END
49	## BUG bash STDOUT:
50	foo=bar
51	spam=eggs
52	bar
53	None
54	## END
55
56	#### true is not special
57	foo=bar true
58	echo $foo
59	## stdout:
60
61	#### Shift is special and the whole script exits if it returns non-zero
62	test -n "$BASH_VERSION" && set -o posix
63	set -- a b
64	shift 3
65	echo status=$?
66	## stdout-json: ""
67	## status: 1
68	## OK dash status: 2
69	## BUG bash/zsh status: 0
70	## BUG bash/zsh STDOUT:
71	status=1
72	## END
73
74	#### set is special and fails, even if using || true
75	shopt -s invalid_ || true
76	echo ok
77	set -o invalid_ || true
78	echo should not get here
79	## STDOUT:
80	ok
81	## END
82	## status: 1
83	## OK dash status: 2
84	## BUG bash status: 0
85	## BUG bash STDOUT:
86	ok
87	should not get here
88	## END
89
90	#### Special builtins can't be redefined as functions
91	# bash manual says they are 'found before' functions.
92	test -n "$BASH_VERSION" && set -o posix
93	export() {
94	echo 'export func'
95	}
96	export hi
97	echo status=$?
98	## status: 2
99	## BUG mksh/zsh status: 0
100	## BUG mksh/zsh stdout: status=0
101
102	#### Non-special builtins CAN be redefined as functions
103	test -n "$BASH_VERSION" && set -o posix
104	true() {
105	echo 'true func'
106	}
107	true hi
108	echo status=$?
109	## STDOUT:
110	true func
111	status=0
112	## END