InstallableFlake::toDerivedPaths(): Support paths and store paths

This makes 'nix build' work on paths (which will be copied to the
store) and store paths (returned as is). E.g. the following flake
output attributes can be built using 'nix build .#foo':

  foo = ./src;
  foo = self.outPath;
  foo = builtins.fetchTarball { ... };
  foo = (builtins.fetchTree { .. }).outPath;
  foo = builtins.fetchTree { .. } + "/README.md";
  foo = builtins.storePath /nix/store/...;

Note that this is potentially risky, e.g.

  foo = /.;

will cause Nix to try to copy the entire file system to the store.

What doesn't work yet:

  foo = self;
  foo = builtins.fetchTree { .. };

because we don't handle attrsets with an outPath attribute in it yet,
and

  foo = builtins.storePath /nix/store/.../README.md;

since result symlinks have to point to a store path currently (rather
than a file inside a store path).

Fixes #7417.
This commit is contained in:
Eelco Dolstra 2022-12-15 23:01:15 +01:00
parent bda879170f
commit 5c97b5a398
3 changed files with 99 additions and 2 deletions

View file

@ -610,8 +610,38 @@ DerivedPathsWithInfo InstallableFlake::toDerivedPaths()
auto attrPath = attr->getAttrPathStr(); auto attrPath = attr->getAttrPathStr();
if (!attr->isDerivation()) if (!attr->isDerivation()) {
throw Error("flake output attribute '%s' is not a derivation", attrPath);
// FIXME: use eval cache?
auto v = attr->forceValue();
if (v.type() == nPath) {
PathSet context;
auto storePath = state->copyPathToStore(context, Path(v.path));
return {{
.path = DerivedPath::Opaque {
.path = std::move(storePath),
}
}};
}
else if (v.type() == nString) {
PathSet context;
auto s = state->forceString(v, context);
auto storePath = state->store->maybeParseStorePath(s);
if (storePath && context.count(std::string(s))) {
return {{
.path = DerivedPath::Opaque {
.path = std::move(*storePath),
}
}};
} else
throw Error("flake output attribute '%s' evaluates to a string that does not denote a store path", attrPath);
}
else
throw Error("flake output attribute '%s' is not a derivation or path", attrPath);
}
auto drvPath = attr->forceDerivation(); auto drvPath = attr->forceDerivation();

View file

@ -0,0 +1,66 @@
source ./common.sh
flake1Dir=$TEST_ROOT/flake1
flake2Dir=$TEST_ROOT/flake2
mkdir -p $flake1Dir $flake2Dir
writeSimpleFlake $flake2Dir
tar cfz $TEST_ROOT/flake.tar.gz -C $TEST_ROOT flake2
hash=$(nix hash path $flake2Dir)
dep=$(nix store add-path ./common.sh)
cat > $flake1Dir/flake.nix <<EOF
{
inputs.flake2.url = "file://$TEST_ROOT/flake.tar.gz";
outputs = { self, flake2 }: {
a1 = builtins.fetchTarball {
#type = "tarball";
url = "file://$TEST_ROOT/flake.tar.gz";
sha256 = "$hash";
};
a2 = ./foo;
a3 = ./.;
a4 = self.outPath;
# FIXME
a5 = self;
a6 = flake2.outPath;
# FIXME
a7 = "${flake2}/config.nix";
# This is only allowed in impure mode.
a8 = builtins.storePath $dep;
a9 = "$dep";
};
}
EOF
echo bar > $flake1Dir/foo
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a1
[[ -e $TEST_ROOT/result/simple.nix ]]
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a2
[[ $(cat $TEST_ROOT/result) = bar ]]
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a3
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a4
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a6
[[ -e $TEST_ROOT/result/simple.nix ]]
nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a8
diff common.sh $TEST_ROOT/result
(! nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a9)

View file

@ -9,6 +9,7 @@ nix_tests = \
flakes/check.sh \ flakes/check.sh \
flakes/unlocked-override.sh \ flakes/unlocked-override.sh \
flakes/absolute-paths.sh \ flakes/absolute-paths.sh \
flakes/build-paths.sh \
ca/gc.sh \ ca/gc.sh \
gc.sh \ gc.sh \
remote-store.sh \ remote-store.sh \