lix/tests/nix-shell.sh
Maximilian Bosch 98946e2d9c
nix-shell: restore backwards-compat with old nixpkgs
Basically an attempt to resume fixing #5543 for a breakage introduced
earlier[1]. Basically, when evaluating an older `nixpkgs` with
`nix-shell` the following error occurs:

    λ ma27 [~] → nix-shell -I nixpkgs=channel:nixos-18.03 -p nix
    error: anonymous function at /nix/store/zakqwc529rb6xcj8pwixjsxscvlx9fbi-source/pkgs/top-level/default.nix:20:1 called with unexpected argument 'inNixShell'

           at /nix/store/zakqwc529rb6xcj8pwixjsxscvlx9fbi-source/pkgs/top-level/impure.nix:82:1:

               81|
               82| import ./. (builtins.removeAttrs args [ "system" "platform" ] // {
                 | ^
               83|   inherit config overlays crossSystem;

This is a problem because one of the main selling points of Nix is that
you can evaluate any old Nix expression and still get the same result
(which also means that it *still evaluates*). In fact we're deprecating,
but not removing a lot of stuff for that reason such as unquoted URLs[2]
or `builtins.toPath`. However this property was essentially thrown away
here.

The change is rather simple: check if `inNixShell` is specified in the
formals of an auto-called function. This means that

    { inNixShell ? false }:
    builtins.trace inNixShell
      (with import <nixpkgs> { }; makeShell { name = "foo"; })

will show `trace: true` while

    args@{ ... }:
    builtins.trace args.inNixShell
      (with import <nixpkgs> { }; makeShell { name = "foo"; })

will throw the following error:

    error: attribute 'inNixShell' missing

This is explicitly needed because the function in
`pkgs/top-level/impure.nix` of e.g. NixOS 18.03 has an ellipsis[3], but
passes the attribute-set on to another lambda with formals that doesn't
have an ellipsis anymore (hence the error from above). This was perhaps
a mistake, but we can't fix it anymore. This also means that there's
AFAICS no proper way to check if the attr-set that's passed to the Nix
code via `EvalState::autoCallFunction` is eventually passed to a lambda
with formals where `inNixShell` is missing.

However, this fix comes with a certain price. Essentially every
`shell.nix` that assumes `inNixShell` to be passed to the formals even
without explicitly specifying it would break with this[4]. However I think
that this is ugly, but preferable:

* Nix 2.3 was declared stable by NixOS up until recently (well, it still
  is as long as 21.11 is alive), so most people might not have even
  noticed that feature.

* We're talking about a way shorter time-span with this change being
  in the wild, so the fallout should be smaller IMHO.

[1] 9d612c393a
[2] https://github.com/NixOS/rfcs/pull/45#issuecomment-488232537
[3] https://github.com/NixOS/nixpkgs/blob/release-18.03/pkgs/top-level/impure.nix#L75
[4] See e.g. the second expression in this commit-message or the changes
    for `tests/ca/nix-shell.sh`.
2022-06-13 23:29:28 +02:00

112 lines
4.4 KiB
Bash

source common.sh
clearStore
if [[ -n ${CONTENT_ADDRESSED:-} ]]; then
shellDotNix="$PWD/ca-shell.nix"
else
shellDotNix="$PWD/shell.nix"
fi
export NIX_PATH=nixpkgs="$shellDotNix"
# Test nix-shell -A
export IMPURE_VAR=foo
export SELECTED_IMPURE_VAR=baz
output=$(nix-shell --pure "$shellDotNix" -A shellDrv --run \
'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $TEST_inNixShell"')
[ "$output" = " - foo - bar - true" ]
# Test --keep
output=$(nix-shell --pure --keep SELECTED_IMPURE_VAR "$shellDotNix" -A shellDrv --run \
'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $SELECTED_IMPURE_VAR"')
[ "$output" = " - foo - bar - baz" ]
# Test nix-shell on a .drv
[[ $(nix-shell --pure $(nix-instantiate "$shellDotNix" -A shellDrv) --run \
'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $TEST_inNixShell"') = " - foo - bar - false" ]]
[[ $(nix-shell --pure $(nix-instantiate "$shellDotNix" -A shellDrv) --run \
'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX - $TEST_inNixShell"') = " - foo - bar - false" ]]
# Test nix-shell on a .drv symlink
# Legacy: absolute path and .drv extension required
nix-instantiate "$shellDotNix" -A shellDrv --add-root $TEST_ROOT/shell.drv
[[ $(nix-shell --pure $TEST_ROOT/shell.drv --run \
'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX"') = " - foo - bar" ]]
# New behaviour: just needs to resolve to a derivation in the store
nix-instantiate "$shellDotNix" -A shellDrv --add-root $TEST_ROOT/shell
[[ $(nix-shell --pure $TEST_ROOT/shell --run \
'echo "$IMPURE_VAR - $VAR_FROM_STDENV_SETUP - $VAR_FROM_NIX"') = " - foo - bar" ]]
# Test nix-shell -p
output=$(NIX_PATH=nixpkgs="$shellDotNix" nix-shell --pure -p foo bar --run 'echo "$(foo) $(bar)"')
[ "$output" = "foo bar" ]
# Test nix-shell -p --arg x y
output=$(NIX_PATH=nixpkgs="$shellDotNix" nix-shell --pure -p foo --argstr fooContents baz --run 'echo "$(foo)"')
[ "$output" = "baz" ]
# Test nix-shell shebang mode
sed -e "s|@ENV_PROG@|$(type -P env)|" shell.shebang.sh > $TEST_ROOT/shell.shebang.sh
chmod a+rx $TEST_ROOT/shell.shebang.sh
output=$($TEST_ROOT/shell.shebang.sh abc def)
[ "$output" = "foo bar abc def" ]
# Test nix-shell shebang mode again with metacharacters in the filename.
# First word of filename is chosen to not match any file in the test root.
sed -e "s|@ENV_PROG@|$(type -P env)|" shell.shebang.sh > $TEST_ROOT/spaced\ \\\'\"shell.shebang.sh
chmod a+rx $TEST_ROOT/spaced\ \\\'\"shell.shebang.sh
output=$($TEST_ROOT/spaced\ \\\'\"shell.shebang.sh abc def)
[ "$output" = "foo bar abc def" ]
# Test nix-shell shebang mode for ruby
# This uses a fake interpreter that returns the arguments passed
# This, in turn, verifies the `rc` script is valid and the `load()` script (given using `-e`) is as expected.
sed -e "s|@SHELL_PROG@|$(type -P nix-shell)|" shell.shebang.rb > $TEST_ROOT/shell.shebang.rb
chmod a+rx $TEST_ROOT/shell.shebang.rb
output=$($TEST_ROOT/shell.shebang.rb abc ruby)
[ "$output" = '-e load(ARGV.shift) -- '"$TEST_ROOT"'/shell.shebang.rb abc ruby' ]
# Test nix-shell shebang mode for ruby again with metacharacters in the filename.
# Note: fake interpreter only space-separates args without adding escapes to its output.
sed -e "s|@SHELL_PROG@|$(type -P nix-shell)|" shell.shebang.rb > $TEST_ROOT/spaced\ \\\'\"shell.shebang.rb
chmod a+rx $TEST_ROOT/spaced\ \\\'\"shell.shebang.rb
output=$($TEST_ROOT/spaced\ \\\'\"shell.shebang.rb abc ruby)
[ "$output" = '-e load(ARGV.shift) -- '"$TEST_ROOT"'/spaced \'\''"shell.shebang.rb abc ruby' ]
# Test 'nix develop'.
nix develop -f "$shellDotNix" shellDrv -c bash -c '[[ -n $stdenv ]]'
# Ensure `nix develop -c` preserves stdin
echo foo | nix develop -f "$shellDotNix" shellDrv -c cat | grep -q foo
# Ensure `nix develop -c` actually executes the command if stdout isn't a terminal
nix develop -f "$shellDotNix" shellDrv -c echo foo |& grep -q foo
# Test 'nix print-dev-env'.
[[ $(nix print-dev-env -f "$shellDotNix" shellDrv --json | jq -r .variables.arr1.value[2]) = '3 4' ]]
source <(nix print-dev-env -f "$shellDotNix" shellDrv)
[[ -n $stdenv ]]
[[ ${arr1[2]} = "3 4" ]]
[[ ${arr2[1]} = $'\n' ]]
[[ ${arr2[2]} = $'x\ny' ]]
[[ $(fun) = blabla ]]
# Test nix-shell with ellipsis and no `inNixShell` argument (for backwards compat with old nixpkgs)
cat >$TEST_ROOT/shell-ellipsis.nix <<EOF
{ system ? "x86_64-linux", ... }:
(import $shellDotNix { }).shellDrv
EOF
nix-shell $TEST_ROOT/shell-ellipsis.nix --run "true"