From 86b05ccd54f2e98ac2b5cef3bcecb29ed6ec4fd8 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Fri, 25 Mar 2022 14:04:18 +0100 Subject: [PATCH 1/3] Only provide builtin.{getFlake,fetchClosure} is the corresponding experimental feature is enabled This allows writing fallback code like if builtins ? fetchClosure then builtins.fetchClose { ... } else builtins.storePath ... --- doc/manual/src/release-notes/rl-next.md | 9 ++++++--- src/libexpr/eval.cc | 17 ----------------- src/libexpr/eval.hh | 6 ------ src/libexpr/flake/flake.cc | 9 ++++++--- src/libexpr/primops.cc | 20 ++++++++++++-------- src/libexpr/primops.hh | 2 ++ src/libexpr/primops/fetchClosure.cc | 6 ++++-- src/nix/main.cc | 1 + 8 files changed, 31 insertions(+), 39 deletions(-) diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md index 33eaa8a2c..2ec864ee4 100644 --- a/doc/manual/src/release-notes/rl-next.md +++ b/doc/manual/src/release-notes/rl-next.md @@ -5,9 +5,12 @@ * `nix store make-content-addressable` has been renamed to `nix store make-content-addressed`. -* New builtin function `builtins.fetchClosure` that copies a closure - from a binary cache at evaluation time and rewrites it to - content-addressed form (if it isn't already). Like +* New experimental builtin function `builtins.fetchClosure` that + copies a closure from a binary cache at evaluation time and rewrites + it to content-addressed form (if it isn't already). Like `builtins.storePath`, this allows importing pre-built store paths; the difference is that it doesn't require the user to configure binary caches and trusted public keys. + + This function is only available if you enable the experimental + feature `fetch-closure`. diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc index 3ec5ed202..437c7fc53 100644 --- a/src/libexpr/eval.cc +++ b/src/libexpr/eval.cc @@ -507,23 +507,6 @@ EvalState::~EvalState() } -void EvalState::requireExperimentalFeatureOnEvaluation( - const ExperimentalFeature & feature, - const std::string_view fName, - const Pos & pos) -{ - if (!settings.isExperimentalFeatureEnabled(feature)) { - throw EvalError({ - .msg = hintfmt( - "Cannot call '%2%' because experimental Nix feature '%1%' is disabled. You can enable it via '--extra-experimental-features %1%'.", - feature, - fName - ), - .errPos = pos - }); - } -} - void EvalState::allowPath(const Path & path) { if (allowedPaths) diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh index 198a62ad2..ab46b448c 100644 --- a/src/libexpr/eval.hh +++ b/src/libexpr/eval.hh @@ -149,12 +149,6 @@ public: std::shared_ptr buildStore = nullptr); ~EvalState(); - void requireExperimentalFeatureOnEvaluation( - const ExperimentalFeature &, - const std::string_view fName, - const Pos & pos - ); - void addToSearchPath(const std::string & s); SearchPath getSearchPath() { return searchPath; } diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc index 6a1aca40d..fdcfb18d7 100644 --- a/src/libexpr/flake/flake.cc +++ b/src/libexpr/flake/flake.cc @@ -706,8 +706,6 @@ void callFlake(EvalState & state, static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Value & v) { - state.requireExperimentalFeatureOnEvaluation(Xp::Flakes, "builtins.getFlake", pos); - std::string flakeRefS(state.forceStringNoCtx(*args[0], pos)); auto flakeRef = parseFlakeRef(flakeRefS, {}, true); if (evalSettings.pureEval && !flakeRef.input.isLocked()) @@ -723,7 +721,12 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va v); } -static RegisterPrimOp r2("__getFlake", 1, prim_getFlake); +static RegisterPrimOp r2({ + .name = "__getFlake", + .args = {"args"}, + .fun = prim_getFlake, + .experimentalFeature = Xp::Flakes, +}); } diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc index f5d9aa9ae..f3eb5e925 100644 --- a/src/libexpr/primops.cc +++ b/src/libexpr/primops.cc @@ -3814,7 +3814,7 @@ RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun) .name = name, .args = {}, .arity = arity, - .fun = fun + .fun = fun, }); } @@ -3886,13 +3886,17 @@ void EvalState::createBaseEnv() if (RegisterPrimOp::primOps) for (auto & primOp : *RegisterPrimOp::primOps) - addPrimOp({ - .fun = primOp.fun, - .arity = std::max(primOp.args.size(), primOp.arity), - .name = symbols.create(primOp.name), - .args = primOp.args, - .doc = primOp.doc, - }); + if (!primOp.experimentalFeature + || settings.isExperimentalFeatureEnabled(*primOp.experimentalFeature)) + { + addPrimOp({ + .fun = primOp.fun, + .arity = std::max(primOp.args.size(), primOp.arity), + .name = symbols.create(primOp.name), + .args = primOp.args, + .doc = primOp.doc, + }); + } /* Add a wrapper around the derivation primop that computes the `drvPath' and `outPath' attributes lazily. */ diff --git a/src/libexpr/primops.hh b/src/libexpr/primops.hh index 5b16e075f..905bd0366 100644 --- a/src/libexpr/primops.hh +++ b/src/libexpr/primops.hh @@ -16,6 +16,7 @@ struct RegisterPrimOp size_t arity = 0; const char * doc; PrimOpFun fun; + std::optional experimentalFeature; }; typedef std::vector PrimOps; @@ -35,6 +36,7 @@ struct RegisterPrimOp /* These primops are disabled without enableNativeCode, but plugins may wish to use them in limited contexts without globally enabling them. */ + /* Load a ValueInitializer from a DSO and return whatever it initializes */ void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value & v); diff --git a/src/libexpr/primops/fetchClosure.cc b/src/libexpr/primops/fetchClosure.cc index 47f40ef33..efeb93daf 100644 --- a/src/libexpr/primops/fetchClosure.cc +++ b/src/libexpr/primops/fetchClosure.cc @@ -7,8 +7,6 @@ namespace nix { static void prim_fetchClosure(EvalState & state, const Pos & pos, Value * * args, Value & v) { - settings.requireExperimentalFeature(Xp::FetchClosure); - state.forceAttrs(*args[0], pos); std::optional fromStoreUrl; @@ -145,8 +143,12 @@ static RegisterPrimOp primop_fetchClosure({ specifying a binary cache from which the path can be fetched. Also, requiring a content-addressed final store path avoids the need for users to configure binary cache public keys. + + This function is only available if you enable the experimental + feature `fetch-closure`. )", .fun = prim_fetchClosure, + .experimentalFeature = Xp::FetchClosure, }); } diff --git a/src/nix/main.cc b/src/nix/main.cc index 9bc6c15fa..6198681e7 100644 --- a/src/nix/main.cc +++ b/src/nix/main.cc @@ -289,6 +289,7 @@ void mainWrapped(int argc, char * * argv) } if (argc == 2 && std::string(argv[1]) == "__dump-builtins") { + settings.experimentalFeatures = {Xp::Flakes, Xp::FetchClosure}; evalSettings.pureEval = false; EvalState state({}, openStore("dummy://")); auto res = nlohmann::json::object(); From 8c363eb3eb3db96287a10eb5fcde23986a96164f Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Fri, 25 Mar 2022 14:19:55 +0100 Subject: [PATCH 2/3] Document getFlake Fixes #5523. --- src/libexpr/flake/flake.cc | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc index fdcfb18d7..22257c6b3 100644 --- a/src/libexpr/flake/flake.cc +++ b/src/libexpr/flake/flake.cc @@ -724,6 +724,24 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va static RegisterPrimOp r2({ .name = "__getFlake", .args = {"args"}, + .doc = R"( + Fetch a flake from a flake reference, and return its output attributes and some metadata. For example: + + ```nix + (builtins.getFlake "nix/55bc52401966fbffa525c574c14f67b00bc4fb3a").packages.x86_64-linux.nix + ``` + + Unless impure evaluation is allowed (`--impure`), the flake reference + must be "locked", e.g. contain a Git revision or content hash. An + example of an unlocked usage is: + + ```nix + (builtins.getFlake "github:edolstra/dwarffs").rev + ``` + + This function is only available if you enable the experimental feature + `flakes`. + )", .fun = prim_getFlake, .experimentalFeature = Xp::Flakes, }); From fc35b11a7cde047cd799a6c83b0da312b713e0fb Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Fri, 25 Mar 2022 15:22:22 +0100 Subject: [PATCH 3/3] Fix mismatched tag warning on clang --- src/libexpr/eval.hh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh index ab46b448c..e7915dd99 100644 --- a/src/libexpr/eval.hh +++ b/src/libexpr/eval.hh @@ -17,7 +17,7 @@ namespace nix { -struct Store; +class Store; class EvalState; class StorePath; enum RepairFlag : bool;