6905291daf
I think that it's not very helpful to get "cached failures" in a wrong `flake.nix`. This can be very confusing when debugging a Nix expression. See for instance NixOS/nixpkgs#118115. In fact, the eval cache allows a forced reevaluation which is used for e.g. `nix eval`. This change makes sure that this is the case for `nix build` as well. So rather than λ ma27 [~/Projects/exp] → ../nix/outputs/out/bin/nix build -L --rebuild --experimental-features 'nix-command flakes' error: cached failure of attribute 'defaultPackage.x86_64-linux' the evaluation of already-evaluated (and failed) attributes looks like this now: λ ma27 [~/Projects/exp] → ../nix/outputs/out/bin/nix build -L --rebuild --experimental-features 'nix-command flakes' error: attribute 'hell' missing at /nix/store/mrnvi9ss8zn5wj6gpn4bcd68vbh42mfh-source/flake.nix:6:35: 5| 6| packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hell; | ^ 7| (use '--show-trace' to show detailed location information)
124 lines
2.6 KiB
C++
124 lines
2.6 KiB
C++
#pragma once
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#include "sync.hh"
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#include "hash.hh"
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#include "eval.hh"
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#include <functional>
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#include <variant>
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namespace nix::eval_cache {
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MakeError(CachedEvalError, EvalError);
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struct AttrDb;
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class AttrCursor;
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class EvalCache : public std::enable_shared_from_this<EvalCache>
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{
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friend class AttrCursor;
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std::shared_ptr<AttrDb> db;
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EvalState & state;
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typedef std::function<Value *()> RootLoader;
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RootLoader rootLoader;
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RootValue value;
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Value * getRootValue();
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public:
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EvalCache(
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std::optional<std::reference_wrapper<const Hash>> useCache,
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EvalState & state,
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RootLoader rootLoader);
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std::shared_ptr<AttrCursor> getRoot();
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};
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enum AttrType {
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Placeholder = 0,
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FullAttrs = 1,
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String = 2,
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Missing = 3,
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Misc = 4,
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Failed = 5,
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Bool = 6,
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};
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struct placeholder_t {};
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struct missing_t {};
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struct misc_t {};
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struct failed_t {};
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typedef uint64_t AttrId;
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typedef std::pair<AttrId, Symbol> AttrKey;
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typedef std::pair<std::string, std::vector<std::pair<Path, std::string>>> string_t;
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typedef std::variant<
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std::vector<Symbol>,
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string_t,
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placeholder_t,
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missing_t,
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misc_t,
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failed_t,
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bool
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> AttrValue;
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class AttrCursor : public std::enable_shared_from_this<AttrCursor>
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{
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friend class EvalCache;
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ref<EvalCache> root;
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typedef std::optional<std::pair<std::shared_ptr<AttrCursor>, Symbol>> Parent;
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Parent parent;
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RootValue _value;
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std::optional<std::pair<AttrId, AttrValue>> cachedValue;
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AttrKey getKey();
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Value & getValue();
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public:
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AttrCursor(
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ref<EvalCache> root,
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Parent parent,
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Value * value = nullptr,
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std::optional<std::pair<AttrId, AttrValue>> && cachedValue = {});
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std::vector<Symbol> getAttrPath() const;
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std::vector<Symbol> getAttrPath(Symbol name) const;
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std::string getAttrPathStr() const;
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std::string getAttrPathStr(Symbol name) const;
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std::shared_ptr<AttrCursor> maybeGetAttr(Symbol name, bool forceErrors = false);
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std::shared_ptr<AttrCursor> maybeGetAttr(std::string_view name);
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std::shared_ptr<AttrCursor> getAttr(Symbol name, bool forceErrors = false);
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std::shared_ptr<AttrCursor> getAttr(std::string_view name);
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std::shared_ptr<AttrCursor> findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force = false);
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std::string getString();
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string_t getStringWithContext();
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bool getBool();
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std::vector<Symbol> getAttrs();
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bool isDerivation();
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Value & forceValue();
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/* Force creation of the .drv file in the Nix store. */
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StorePath forceDerivation();
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};
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}
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