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https://github.com/NixOS/nix
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929423476e
This is useful for frameworks (such as flake-parts) to avoid unnecessary evaluation. See discussion here: https://github.com/hercules-ci/flake-parts/issues/288#issuecomment-2912459614 While digging into this, I discovered that `nix fmt` already handles `null` formatters identically to undefined formatters. I added a couple of tests to demonstrate this behavior. `nix flake show` needs some reworking to avoid crashing with a "error: expected a derivation" when it encounters a `null` formatter or package. My changes here avoid the crash, but has some cosmetic issues, which is why I've labeled this PR as a draft. Cosmetic issues =============== With the following `flake.nix`: ```nix { outputs = _: { packages.x86_64-linux.default = null; }; } ``` `nix flake show` shows a weird empty system: ``` $ nix flake show path:/tmp/tmp.uL0iGuNwXB?lastModified=1748472558&narHash=sha256-tC%2BhdXAyoeFvWHNllJbois8X%2B7wpZ6CJzEzbcaGQxtM%3D └───packages └───x86_64-linux ``` Similarly, `nix flake show --json` includes an empty object: ``` $ nix flake show --json { "packages": { "x86_64-linux": { "default": null } } } ``` `nix build` crashes: ``` $ nix build .#default error: expected flake output attribute 'packages.x86_64-linux.default' to be a derivation or path but found null: null ```
124 lines
3.1 KiB
Bash
Executable file
124 lines
3.1 KiB
Bash
Executable file
#!/usr/bin/env bash
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source common.sh
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TODO_NixOS # Provide a `shell` variable. Try not to `export` it, perhaps.
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clearStoreIfPossible
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rm -rf "$TEST_HOME"/.cache "$TEST_HOME"/.config "$TEST_HOME"/.local
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cp ./simple.nix ./simple.builder.sh ./formatter.simple.sh "${config_nix}" "$TEST_HOME"
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cd "$TEST_HOME"
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nix formatter --help | grep "build or run the formatter"
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nix fmt --help | grep "reformat your code"
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nix fmt run --help | grep "reformat your code"
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nix fmt build --help | grep "build"
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cat << EOF > flake.nix
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{
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outputs = _: {
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formatter.$system =
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with import ./config.nix;
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mkDerivation {
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name = "formatter";
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buildCommand = ''
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mkdir -p \$out/bin
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echo "#! ${shell}" > \$out/bin/formatter
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cat \${./formatter.simple.sh} >> \$out/bin/formatter
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chmod +x \$out/bin/formatter
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'';
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};
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};
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}
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EOF
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mkdir subflake
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cp ./simple.nix ./simple.builder.sh ./formatter.simple.sh "${config_nix}" "$TEST_HOME/subflake"
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cat << EOF > subflake/flake.nix
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{
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outputs = _: {
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formatter.$system =
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with import ./config.nix;
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mkDerivation {
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name = "formatter";
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buildCommand = ''
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mkdir -p \$out/bin
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echo "#! ${shell}" > \$out/bin/formatter
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cat \${./formatter.simple.sh} >> \$out/bin/formatter
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chmod +x \$out/bin/formatter
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'';
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};
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};
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}
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EOF
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# No arguments check
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[[ "$(nix fmt)" = "PRJ_ROOT=$TEST_HOME Formatting(0):" ]]
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[[ "$(nix formatter run)" = "PRJ_ROOT=$TEST_HOME Formatting(0):" ]]
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# Argument forwarding check
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nix fmt ./file ./folder | grep "PRJ_ROOT=$TEST_HOME Formatting(2): ./file ./folder"
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nix formatter run ./file ./folder | grep "PRJ_ROOT=$TEST_HOME Formatting(2): ./file ./folder"
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# test subflake
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cd subflake
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nix fmt ./file | grep "PRJ_ROOT=$TEST_HOME/subflake Formatting(1): ./file"
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# Build checks
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## Defaults to a ./result.
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nix formatter build | grep ".\+/bin/formatter"
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[[ -L ./result ]]
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rm result
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## Can prevent the symlink.
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nix formatter build --no-link
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[[ ! -e ./result ]]
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## Can change the symlink name.
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nix formatter build --out-link my-result | grep ".\+/bin/formatter"
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[[ -L ./my-result ]]
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rm ./my-result
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# Flake outputs check.
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nix flake check
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nix flake show | grep -P "package 'formatter'"
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function expectFailWithOutputMatching() {
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outputMustMatch=$1
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if output=$(nix fmt 2>&1); then
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echo >&2 "nix fmt unexpectedly succeeded"
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exit 1
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fi
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if ! echo "$output" | grep "$outputMustMatch"; then
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echo >&2 "Expected nix fmt output to match:"
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echo >&2 "$outputMustMatch"
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echo >&2 "However, the actual output was:"
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echo >&2 "$output"
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exit 1
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fi
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}
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# Try a flake with no formatter.
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cat << EOF > flake.nix
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{
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outputs = _: {};
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}
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EOF
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expectFailWithOutputMatching "does not provide attribute 'formatter.$system'"
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# Confirm that a null formatter is treated as if there is no formatter.
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cat << EOF > flake.nix
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{
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outputs = _: {
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formatter.$system = null;
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};
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}
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EOF
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if nix fmt | grep "does not provide attribute 'formatter.$system'"; then
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echo >&2 "nix fmt unexpectedly succeeded"
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exit 1
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fi
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