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nix/src/libflake/call-flake.nix
Robert Hensing 818fc68db6 fix: Evaluate flake parent source without evaluating its outputs
This requires that we refer to the `sourceInfo` instead of the
`result`. However, `sourceInfo` does not create a chain of basedir
resolution, so we add that back with `flakeDir`.

(cherry picked from commit 2109a5a206)
2025-04-15 11:52:46 +00:00

109 lines
3.2 KiB
Nix

# This is a helper to callFlake() to lazily fetch flake inputs.
# The contents of the lock file, in JSON format.
lockFileStr:
# A mapping of lock file node IDs to { sourceInfo, subdir } attrsets,
# with sourceInfo.outPath providing an SourceAccessor to a previously
# fetched tree. This is necessary for possibly unlocked inputs, in
# particular the root input, but also --override-inputs pointing to
# unlocked trees.
overrides:
# This is `prim_fetchFinalTree`.
fetchTreeFinal:
let
inherit (builtins) mapAttrs;
lockFile = builtins.fromJSON lockFileStr;
# Resolve a input spec into a node name. An input spec is
# either a node name, or a 'follows' path from the root
# node.
resolveInput =
inputSpec: if builtins.isList inputSpec then getInputByPath lockFile.root inputSpec else inputSpec;
# Follow an input attrpath (e.g. ["dwarffs" "nixpkgs"]) from the
# root node, returning the final node.
getInputByPath =
nodeName: path:
if path == [ ] then
nodeName
else
getInputByPath
# Since this could be a 'follows' input, call resolveInput.
(resolveInput lockFile.nodes.${nodeName}.inputs.${builtins.head path})
(builtins.tail path);
allNodes = mapAttrs (
key: node:
let
parentNode = allNodes.${getInputByPath lockFile.root node.parent};
flakeDir =
let
dir = overrides.${key}.dir or node.locked.path or "";
parentDir = parentNode.flakeDir;
in
if node ? parent then parentDir + ("/" + dir) else dir;
sourceInfo =
if overrides ? ${key} then
overrides.${key}.sourceInfo
else if node.locked.type == "path" && builtins.substring 0 1 node.locked.path != "/" then
parentNode.sourceInfo
// {
outPath = parentNode.sourceInfo.outPath + ("/" + flakeDir);
}
else
# FIXME: remove obsolete node.info.
# Note: lock file entries are always final.
fetchTreeFinal (node.info or { } // removeAttrs node.locked [ "dir" ]);
subdir = overrides.${key}.dir or node.locked.dir or "";
outPath = sourceInfo + ((if subdir == "" then "" else "/") + subdir);
flake = import (outPath + "/flake.nix");
inputs = mapAttrs (inputName: inputSpec: allNodes.${resolveInput inputSpec}.result) (
node.inputs or { }
);
outputs = flake.outputs (inputs // { self = result; });
result =
outputs
# We add the sourceInfo attribute for its metadata, as they are
# relevant metadata for the flake. However, the outPath of the
# sourceInfo does not necessarily match the outPath of the flake,
# as the flake may be in a subdirectory of a source.
# This is shadowed in the next //
// sourceInfo
// {
# This shadows the sourceInfo.outPath
inherit outPath;
inherit inputs;
inherit outputs;
inherit sourceInfo;
_type = "flake";
};
in
{
result =
if node.flake or true then
assert builtins.isFunction flake.outputs;
result
else
sourceInfo;
inherit flakeDir sourceInfo;
}
) lockFile.nodes;
in
allNodes.${lockFile.root}.result