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Merge "Revert "Revert "Merge pull request #6621 from Kha/nested-follows""" into main

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Maximilian Bosch 2024-05-04 08:52:29 +00:00 committed by Gerrit Code Review
commit 799d0132f0
3 changed files with 115 additions and 13 deletions
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21
doc/manual/rl-next/fix-nested-follows.md Normal file
View file

@ -0,0 +1,21 @@
---
synopsis: Fix nested flake input `follows`
prs: 6621
cls: 994
---
Previously nested-input overrides were ignored; that is, the following did not
override anything, in spite of the `nix3-flake` manual documenting it working:
```
{
inputs = {
foo.url = "github:bar/foo";
foo.inputs.bar.inputs.nixpkgs = "nixpkgs";
};
}
```
This is useful to avoid the 1000 instances of nixpkgs problem without having
each flake in the dependency tree to expose all of its transitive dependencies
for modification.

47
src/libexpr/flake/flake.cc
View file

@ -91,11 +91,11 @@ static void expectType(EvalState & state, ValueType type,
static std::map<FlakeId, FlakeInput> parseFlakeInputs(
EvalState & state, Value * value, const PosIdx pos,
const std::optional<Path> & baseDir, InputPath lockRootPath);
const std::optional<Path> & baseDir, InputPath lockRootPath, unsigned depth);
static FlakeInput parseFlakeInput(EvalState & state,
const std::string & inputName, Value * value, const PosIdx pos,
const std::optional<Path> & baseDir, InputPath lockRootPath)
const std::optional<Path> & baseDir, InputPath lockRootPath, unsigned depth)
{
expectType(state, nAttrs, *value, pos);
@ -119,7 +119,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
expectType(state, nBool, *attr.value, attr.pos);
input.isFlake = attr.value->boolean;
} else if (attr.name == sInputs) {
input.overrides = parseFlakeInputs(state, attr.value, attr.pos, baseDir, lockRootPath);
input.overrides = parseFlakeInputs(state, attr.value, attr.pos, baseDir, lockRootPath, depth + 1);
} else if (attr.name == sFollows) {
expectType(state, nString, *attr.value, attr.pos);
auto follows(parseInputPath(attr.value->string.s));
@ -168,7 +168,11 @@ static FlakeInput parseFlakeInput(EvalState & state,
input.ref = parseFlakeRef(*url, baseDir, true, input.isFlake);
}
if (!input.follows && !input.ref)
if (!input.follows && !input.ref && depth == 0)
// in `input.nixops.inputs.nixpkgs.url = ...`, we assume `nixops` is from
// the flake registry absent `ref`/`follows`, but we should not assume so
// about `nixpkgs` (where `depth == 1`) as the `nixops` flake should
// determine its default source
input.ref = FlakeRef::fromAttrs({{"type", "indirect"}, {"id", inputName}});
return input;
@ -176,7 +180,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
static std::map<FlakeId, FlakeInput> parseFlakeInputs(
EvalState & state, Value * value, const PosIdx pos,
const std::optional<Path> & baseDir, InputPath lockRootPath)
const std::optional<Path> & baseDir, InputPath lockRootPath, unsigned depth)
{
std::map<FlakeId, FlakeInput> inputs;
@ -189,7 +193,8 @@ static std::map<FlakeId, FlakeInput> parseFlakeInputs(
inputAttr.value,
inputAttr.pos,
baseDir,
lockRootPath));
lockRootPath,
depth));
}
return inputs;
@ -239,7 +244,7 @@ static Flake getFlake(
auto sInputs = state.symbols.create("inputs");
if (auto inputs = vInfo.attrs->get(sInputs))
flake.inputs = parseFlakeInputs(state, inputs->value, inputs->pos, flakeDir, lockRootPath);
flake.inputs = parseFlakeInputs(state, inputs->value, inputs->pos, flakeDir, lockRootPath, 0);
auto sOutputs = state.symbols.create("outputs");
@ -322,6 +327,19 @@ Flake getFlake(EvalState & state, const FlakeRef & originalRef, bool allowLookup
return getFlake(state, originalRef, allowLookup, flakeCache);
}
/* Recursively merge `overrides` into `overrideMap` */
static void updateOverrides(std::map<InputPath, FlakeInput> & overrideMap, const FlakeInputs & overrides,
const InputPath & inputPathPrefix)
{
for (auto & [id, input] : overrides) {
auto inputPath(inputPathPrefix);
inputPath.push_back(id);
// Do not override existing assignment from outer flake
overrideMap.insert({inputPath, input});
updateOverrides(overrideMap, input.overrides, inputPath);
}
}
/* Compute an in-memory lock file for the specified top-level flake,
and optionally write it to file, if the flake is writable. */
LockedFlake lockFlake(
@ -394,12 +412,9 @@ LockedFlake lockFlake(
/* Get the overrides (i.e. attributes of the form
'inputs.nixops.inputs.nixpkgs.url = ...'). */
for (auto & [id, input] : flakeInputs) {
for (auto & [idOverride, inputOverride] : input.overrides) {
auto inputPath(inputPathPrefix);
inputPath.push_back(id);
inputPath.push_back(idOverride);
overrides.insert_or_assign(inputPath, inputOverride);
}
auto inputPath(inputPathPrefix);
inputPath.push_back(id);
updateOverrides(overrides, input.overrides, inputPath);
}
/* Check whether this input has overrides for a
@ -434,6 +449,12 @@ LockedFlake lockFlake(
// Respect the “flakeness” of the input even if we
// override it
i->second.isFlake = input2.isFlake;
if (!i->second.ref)
i->second.ref = input2.ref;
if (!i->second.follows)
i->second.follows = input2.follows;
// Note that `input.overrides` is not used in the following,
// so no need to merge it here (already done by `updateOverrides`)
}
auto & input = hasOverride ? i->second : input2;

60
tests/functional/flakes/follow-paths.sh
View file

@ -230,3 +230,63 @@ git -C "$flakeFollowsOverloadA" add flake.nix flakeB/flake.nix \
nix flake metadata "$flakeFollowsOverloadA"
nix flake update --flake "$flakeFollowsOverloadA"
nix flake lock "$flakeFollowsOverloadA"
# Test nested flake overrides: A overrides B/C/D
cat <<EOF > $flakeFollowsD/flake.nix
{ outputs = _: {}; }
EOF
cat <<EOF > $flakeFollowsC/flake.nix
{
inputs.D.url = "path:nosuchflake";
outputs = _: {};
}
EOF
cat <<EOF > $flakeFollowsB/flake.nix
{
inputs.C.url = "path:$flakeFollowsC";
outputs = _: {};
}
EOF
cat <<EOF > $flakeFollowsA/flake.nix
{
inputs.B.url = "path:$flakeFollowsB";
inputs.D.url = "path:$flakeFollowsD";
inputs.B.inputs.C.inputs.D.follows = "D";
outputs = _: {};
}
EOF
nix flake lock $flakeFollowsA
[[ $(jq -c .nodes.C.inputs.D $flakeFollowsA/flake.lock) = '["D"]' ]]
# Test overlapping flake follows: B has D follow C/D, while A has B/C follow C
cat <<EOF > $flakeFollowsC/flake.nix
{
inputs.D.url = "path:$flakeFollowsD";
outputs = _: {};
}
EOF
cat <<EOF > $flakeFollowsB/flake.nix
{
inputs.C.url = "path:nosuchflake";
inputs.D.url = "path:nosuchflake";
inputs.D.follows = "C/D";
outputs = _: {};
}
EOF
cat <<EOF > $flakeFollowsA/flake.nix
{
inputs.B.url = "path:$flakeFollowsB";
inputs.C.url = "path:$flakeFollowsC";
inputs.B.inputs.C.follows = "C";
outputs = _: {};
}
EOF
# bug was not triggered without recreating the lockfile
nix flake update --flake $flakeFollowsA
[[ $(jq -c .nodes.B.inputs.D $flakeFollowsA/flake.lock) = '["B","C","D"]' ]]