cli: disallow impure derivations

we don't remove the entire feature in one go to make review easier.
impure derivations are rather unintrusive on their own, at least if
we compare them to dynamic or ca derivations in general, so we will
be done with this soon. as it stands impure derivations cannot work
without ca derivations, and those we *really* want to leave behind.

Change-Id: I4f01d8d758b2c85dcd6c3078304b5ee1b52f65b0

doc/manual/rl-next/remove-xp-derivations.md

@@ -0,0 +1,14 @@
+---
+synopsis: Remove impure derivations
+issues: [fj#815]
+cls: [3210]
+significance: significant
+category: "Breaking Changes"
+credits: [horrors]
+---
+
+The `impure-derivations` experimental feature has been removed. New impure
+derivations cannot be created from this point forward, and existing impure store
+derivations canot be read or built any more. Derivation outputs created by
+building an impure derivation are still valid until garbage collected; existing
+impure store derivations can only be garbage collected.

lix/libexpr/fetchurl.nix

@@ -34,6 +34,7 @@
   executable ? false,
   unpack ? false,
   name ? baseNameOf (toString url),
+  # still translates to __impure to trigger derivationStrict error checks.
   impure ? false,
 }:
 

lix/libutil/config.cc

@@ -364,8 +364,7 @@ template<> ExperimentalFeatures BaseSetting<ExperimentalFeatures>::parse(const s
                 static std::once_flag warned;
                 warnDeprecated294(warned, s);
             } else if (*thisXpFeature == Xp::ImpureDerivations) {
-                static std::once_flag warned;
-                warnDeprecated294(warned, s);
+                throw Error("impure derivations are no longer supported");
             }
             res = res | thisXpFeature.value();
         } else

tests/functional/impure-derivations.nix

@@ -2,22 +2,6 @@ with import ./config.nix;
 
 rec {
 
-  impure = mkDerivation {
-    name = "impure";
-    outputs = [ "out" "stuff" ];
-    buildCommand =
-      ''
-        echo impure
-        x=$(< $TEST_ROOT/counter)
-        mkdir $out $stuff
-        echo $x > $out/n
-        ln -s $out/n $stuff/bla
-        printf $((x + 1)) > $TEST_ROOT/counter
-      '';
-    __impure = true;
-    impureEnvVars = [ "TEST_ROOT" ];
-  };
-
   impureOnImpure = mkDerivation {
     name = "impure-on-impure";
     buildCommand =

tests/functional/impure-derivations.sh

@@ -1,65 +0,0 @@
-source common.sh
-
-requireDaemonNewerThan "2.8pre20220311"
-
-enableFeatures "ca-derivations impure-derivations"
-restartDaemon
-
-clearStore
-
-# Basic test of impure derivations: building one a second time should not use the previous result.
-printf 0 > $TEST_ROOT/counter
-
-# `nix derivation add` with impure derivations work
-drvPath=$(nix-instantiate ./impure-derivations.nix -A impure)
-nix derivation show $drvPath | jq .[] > $TEST_HOME/impure-drv.json
-drvPath2=$(nix derivation add < $TEST_HOME/impure-drv.json)
-[[ "$drvPath" = "$drvPath2" ]]
-
-# But only with the experimental feature!
-expectStderr 1 nix derivation add < $TEST_HOME/impure-drv.json --experimental-features nix-command | grepQuiet "experimental Lix feature 'impure-derivations' is disabled"
-
-nix build --dry-run --json --file ./impure-derivations.nix impure.all
-json=$(nix build -L --no-link --json --file ./impure-derivations.nix impure.all)
-path1=$(echo $json | jq -r .[].outputs.out)
-path1_stuff=$(echo $json | jq -r .[].outputs.stuff)
-[[ $(< $path1/n) = 0 ]]
-[[ $(< $path1_stuff/bla) = 0 ]]
-
-[[ $(nix path-info --json $path1 | jq .[].ca) =~ fixed:r:sha256: ]]
-
-path2=$(nix build -L --no-link --json --file ./impure-derivations.nix impure | jq -r .[].outputs.out)
-[[ $(< $path2/n) = 1 ]]
-
-# Test impure derivations that depend on impure derivations.
-path3=$(nix build -L --no-link --json --file ./impure-derivations.nix impureOnImpure | jq -r .[].outputs.out)
-[[ $(< $path3/n) = X2 ]]
-
-path4=$(nix build -L --no-link --json --file ./impure-derivations.nix impureOnImpure | jq -r .[].outputs.out)
-[[ $(< $path4/n) = X3 ]]
-
-# Test that (self-)references work.
-[[ $(< $path4/symlink/bla) = 3 ]]
-[[ $(< $path4/self/n) = X3 ]]
-
-# Input-addressed derivations cannot depend on impure derivations directly.
-(! nix build -L --no-link --json --file ./impure-derivations.nix inputAddressed 2>&1) | grep 'depends on impure derivation'
-
-drvPath=$(nix eval --json --file ./impure-derivations.nix impure.drvPath | jq -r .)
-[[ $(nix derivation show $drvPath | jq ".[\"$drvPath\"].outputs.out.impure") = true ]]
-[[ $(nix derivation show $drvPath | jq ".[\"$drvPath\"].outputs.stuff.impure") = true ]]
-
-# Fixed-output derivations *can* depend on impure derivations.
-path5=$(nix build -L --no-link --json --file ./impure-derivations.nix contentAddressed | jq -r .[].outputs.out)
-[[ $(< $path5) = X ]]
-[[ $(< $TEST_ROOT/counter) = 5 ]]
-
-# And they should not be rebuilt.
-path5=$(nix build -L --no-link --json --file ./impure-derivations.nix contentAddressed | jq -r .[].outputs.out)
-[[ $(< $path5) = X ]]
-[[ $(< $TEST_ROOT/counter) = 5 ]]
-
-# Input-addressed derivations can depend on fixed-output derivations that depend on impure derivations.
-path6=$(nix build -L --no-link --json --file ./impure-derivations.nix inputAddressedAfterCA | jq -r .[].outputs.out)
-[[ $(< $path6) = X ]]
-[[ $(< $TEST_ROOT/counter) = 5 ]]

tests/functional/meson.build

@@ -186,7 +186,6 @@ functional_tests_scripts = [
   'fetchClosure.sh',
   'completions.sh',
   'flakes/show.sh',
-  'impure-derivations.sh',
   'path-from-hash-part.sh',
   'toString-path.sh',
   'read-only-store.sh',

tests/unit/libexpr/error_traces.cc

@@ -1290,16 +1290,6 @@ namespace nix {
                       HintFmt("expected a Boolean but found %s: %s", "a string", "\"true\""),
                       HintFmt("while evaluating the attribute '__contentAddressed' of derivation 'foo'"));
 
-        ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"out\"; __impure = \"true\"; }",
-                      TypeError,
-                      HintFmt("expected a Boolean but found %s: %s", "a string", "\"true\""),
-                      HintFmt("while evaluating the attribute '__impure' of derivation 'foo'"));
-
-        ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"out\"; __impure = \"true\"; }",
-                      TypeError,
-                      HintFmt("expected a Boolean but found %s: %s", "a string", "\"true\""),
-                      HintFmt("while evaluating the attribute '__impure' of derivation 'foo'"));
-
         ASSERT_TRACE2("derivationStrict { name = \"foo\"; builder = 1; system = 1; outputs = \"out\"; args = \"foo\"; }",
                       TypeError,
                       HintFmt("expected a list but found %s: %s", "a string", "\"foo\""),

tests/unit/libstore/data/libstore/derivation/output-impure.json

@@ -1,4 +0,0 @@
-{
-  "hashAlgo": "r:sha256",
-  "impure": true
-}

tests/unit/libstore/derivation.cc

@@ -41,14 +41,6 @@ class DynDerivationTest : public DerivationTest
     }
 };
 
-class ImpureDerivationTest : public DerivationTest
-{
-    void SetUp() override
-    {
-        mockXpSettings.set("experimental-features", "impure-derivations");
-    }
-};
-
 TEST_F(DerivationTest, BadATerm_version) {
     ASSERT_THROW(
         parseDerivation(
@@ -154,13 +146,6 @@ TEST_JSON(DerivationTest, deferred,
     DerivationOutput::Deferred { },
     "drv-name", "output-name")
 
-TEST_JSON(ImpureDerivationTest, impure,
-    (DerivationOutput::Impure {
-        .method = FileIngestionMethod::Recursive,
-        .hashType = HashType::SHA256,
-    }),
-    "drv-name", "output-name")
-
 #undef TEST_JSON
 
 #define TEST_JSON(FIXTURE, NAME, VAL)                                     \