1cmake_policy(SET CMP0054 NEW)
2
3function(assert_expected_list_len list_var expected_size)
4    list(LENGTH ${list_var} _size)
5    if(NOT _size EQUAL ${expected_size})
6        message(FATAL_ERROR "list size expected to be `${expected_size}`, got `${_size}` instead")
7    endif()
8endfunction()
9
10# Pop from undefined list
11list(POP_FRONT test)
12if(DEFINED test)
13    message(FATAL_ERROR "`test` expected to be undefined")
14endif()
15
16# Pop from empty list
17set(test)
18list(POP_FRONT test)
19if(DEFINED test)
20    message(FATAL_ERROR "`test` expected to be undefined")
21endif()
22
23# Default pop from 1-item list
24list(APPEND test one)
25list(POP_FRONT test)
26assert_expected_list_len(test 0)
27
28# Pop from 1-item list to var
29list(APPEND test one)
30list(POP_FRONT test one)
31assert_expected_list_len(test 0)
32if(NOT DEFINED one)
33    message(FATAL_ERROR "`one` expected to be defined")
34endif()
35if(NOT one STREQUAL "one")
36    message(FATAL_ERROR "`one` has unexpected value `${one}`")
37endif()
38
39unset(one)
40unset(two)
41
42# Pop from 1-item list to vars
43list(APPEND test one)
44list(POP_FRONT test one two)
45assert_expected_list_len(test 0)
46if(NOT DEFINED one)
47    message(FATAL_ERROR "`one` expected to be defined")
48endif()
49if(NOT one STREQUAL "one")
50    message(FATAL_ERROR "`one` has unexpected value `${one}`")
51endif()
52if(DEFINED two)
53    message(FATAL_ERROR "`two` expected to be undefined")
54endif()
55
56unset(one)
57unset(two)
58
59# Default pop from 2-item list
60list(APPEND test one two)
61list(POP_FRONT test)
62assert_expected_list_len(test 1)
63if(NOT test STREQUAL "two")
64    message(FATAL_ERROR "`test` has unexpected value `${test}`")
65endif()
66
67# Pop from 2-item list
68list(PREPEND test one)
69list(POP_FRONT test one)
70assert_expected_list_len(test 1)
71if(NOT DEFINED one)
72    message(FATAL_ERROR "`one` expected to be defined")
73endif()
74if(NOT one STREQUAL "one")
75    message(FATAL_ERROR "`one` has unexpected value `${one}`")
76endif()
77if(NOT test STREQUAL "two")
78    message(FATAL_ERROR "`test` has unexpected value `${test}`")
79endif()
80
81# BUG 19436
82set(myList a b c)
83list(POP_FRONT myList first second)
84if(NOT first STREQUAL "a")
85    message(FATAL_ERROR "BUG#19436: `first` has unexpected value `${first}`")
86endif()
87if(NOT second STREQUAL "b")
88    message(FATAL_ERROR "BUG#19436: `second` has unexpected value `${second}`")
89endif()
90if(NOT myList STREQUAL "c")
91    message(FATAL_ERROR "BUG#19436: `myList` has unexpected value `${myList}`")
92endif()
93