| 1 | ## compare_shells: bash
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| 2 |
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| 3 | #### var ref to array 'preHooks[@]'
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| 4 | #
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| 5 | # This idiom discussed on
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| 6 | # https://github.com/NixOS/nixpkgs/pull/147629
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| 7 |
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| 8 | show() {
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| 9 | echo show
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| 10 |
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| 11 | # These are actually different
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| 12 | argv.py ${!hooksSlice}
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| 13 |
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| 14 | argv.py ${!hooksSlice+"${!hooksSlice}"}
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| 15 | }
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| 16 |
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| 17 | hooksSlice='preHooks[@]'
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| 18 |
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| 19 | preHooks=()
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| 20 | show
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| 21 |
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| 22 | preHooks=('foo bar' baz)
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| 23 | show
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| 24 |
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| 25 | # WTF this exposes a difference? But not the test case below?
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| 26 |
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| 27 | # What's happening here?
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| 28 | # Uncomment this and get an error in bash about hookSlice, even though we never
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| 29 | # undefined it.
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| 30 |
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| 31 | #wtf=1
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| 32 | #
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| 33 | # line 6: !hooksSlice: unbound variable
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| 34 |
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| 35 | if test -n "$wtf"; then
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| 36 | # 4.4.0(1)-release
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| 37 | # echo $BASH_VERSION
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| 38 |
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| 39 | set -u
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| 40 | preHooks=()
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| 41 | show
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| 42 |
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| 43 | preHooks=('foo bar' baz)
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| 44 | show
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| 45 | fi
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| 46 |
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| 47 | ## STDOUT:
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| 48 | show
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| 49 | []
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| 50 | []
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| 51 | show
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| 52 | ['foo', 'bar', 'baz']
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| 53 | ['foo bar', 'baz']
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| 54 | ## END
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| 55 |
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| 56 | #### Similar to above with set -u
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| 57 | show() {
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| 58 | echo show
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| 59 |
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| 60 | # bash gives an error here - !hookSlice unbound, even though preHooks exists
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| 61 | # OSH currently does the "logical" thing
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| 62 |
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| 63 | # NOT testing this -- I think this is WHAT NIX WORKS AROUND WITH
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| 64 | #argv.py ${!hooksSlice}
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| 65 |
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| 66 | argv.py ${!hooksSlice+"${!hooksSlice}"}
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| 67 | }
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| 68 |
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| 69 | hooksSlice='preHooks[@]'
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| 70 |
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| 71 | set -u
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| 72 | preHooks=()
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| 73 | show
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| 74 |
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| 75 | preHooks=('foo bar' baz)
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| 76 | show
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| 77 |
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| 78 | ## STDOUT:
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| 79 | show
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| 80 | []
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| 81 | show
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| 82 | ['foo bar', 'baz']
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| 83 | ## END
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| 84 |
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| 85 | #### ${!ref} to undefined array
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| 86 |
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| 87 | set -u
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| 88 | shopt -s eval_unsafe_arith || true 2>/dev/null
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| 89 |
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| 90 | #preHooks=()
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| 91 | hookSlice="preHooks[@]"
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| 92 |
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| 93 | argv.py ${!hookSlice+"${!hookSlice}"}
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| 94 |
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| 95 | for element in ${!hookSlice+"${!hookSlice}"}; do
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| 96 | echo $element
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| 97 | done
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| 98 |
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| 99 | ## STDOUT:
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| 100 | []
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| 101 | ## END
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| 102 |
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| 103 | #### ${!ref} to undefined string var is fatal, INCONSISTENT with array
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| 104 | hookSlice='preHooks'
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| 105 |
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| 106 | argv.py ${!hookSlice}
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| 107 |
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| 108 | set -u
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| 109 |
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| 110 | argv.py ${!hookSlice}
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| 111 |
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| 112 | echo end
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| 113 |
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| 114 | ## status: 1
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| 115 | ## STDOUT:
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| 116 | []
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| 117 | ## END
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| 118 |
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| 119 | #### export with dynamic var name +=
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| 120 |
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| 121 | orig() {
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| 122 | export NIX_LDFLAGS${role_post}+=" -L$1/lib64"
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| 123 | }
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| 124 |
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| 125 | new() {
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| 126 | local var_name="NIX_LDFLAGS$role_post"
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| 127 | local value=" -L$1/lib64"
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| 128 |
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| 129 | eval "$var_name"+='$value'
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| 130 | export "$var_name"
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| 131 | }
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| 132 |
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| 133 | role_post='_foo'
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| 134 |
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| 135 | # set -u
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| 136 |
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| 137 | if test -n "${BASH_VERSION:-}"; then
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| 138 | orig one
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| 139 | fi
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| 140 |
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| 141 | declare -p NIX_LDFLAGS_foo # inspect it
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| 142 | unset NIX_LDFLAGS_foo
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| 143 |
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| 144 | new one
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| 145 |
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| 146 | declare -p NIX_LDFLAGS_foo # inspect it
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| 147 |
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| 148 | ## STDOUT:
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| 149 | declare -x NIX_LDFLAGS_foo=" -Lone/lib64"
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| 150 | declare -x NIX_LDFLAGS_foo=" -Lone/lib64"
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| 151 | ## END
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| 152 | ## OK osh STDOUT:
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| 153 | declare -x NIX_LDFLAGS_foo=' -Lone/lib64'
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| 154 | ## END
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| 155 |
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| 156 | #### let idiom can be written in POSIX shell - eval ": \$(( ))"
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| 157 |
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| 158 | for i in 0 1 2; do
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| 159 | echo i=$i
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| 160 |
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| 161 | NIX_ENFORCE_NO_NATIVE=$i
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| 162 |
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| 163 | outputVar=NIX_ENFORCE_NO_NATIVE_x86_64_unknown_linux_gnu
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| 164 | inputVar=NIX_ENFORCE_NO_NATIVE
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| 165 |
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| 166 | # Original Nix idiom
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| 167 |
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| 168 | if test -n "$BASH_VERSION"; then
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| 169 | let "${outputVar} |= ${!inputVar:-0}" "1"
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| 170 | else
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| 171 | # OSH alternative
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| 172 | eval ": \$(( ${outputVar} |= ${!inputVar:-0} ))"
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| 173 | fi
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| 174 |
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| 175 | echo NIX_ENFORCE_NO_NATIVE=$NIX_ENFORCE_NO_NATIVE
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| 176 | echo NIX_ENFORCE_NO_NATIVE_x86_64_unknown_linux_gnu=$NIX_ENFORCE_NO_NATIVE_x86_64_unknown_linux_gnu
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| 177 | echo
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| 178 |
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| 179 | done
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| 180 |
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| 181 |
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| 182 | ## STDOUT:
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| 183 | i=0
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| 184 | NIX_ENFORCE_NO_NATIVE=0
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| 185 | NIX_ENFORCE_NO_NATIVE_x86_64_unknown_linux_gnu=0
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| 186 |
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| 187 | i=1
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| 188 | NIX_ENFORCE_NO_NATIVE=1
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| 189 | NIX_ENFORCE_NO_NATIVE_x86_64_unknown_linux_gnu=1
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| 190 |
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| 191 | i=2
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| 192 | NIX_ENFORCE_NO_NATIVE=2
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| 193 | NIX_ENFORCE_NO_NATIVE_x86_64_unknown_linux_gnu=3
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| 194 |
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| 195 | ## END
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| 196 |
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