Make more string values work as installables

As discussed in #7417, it would be good to make more string values work
as installables. That is to say, if an installable refers to a value,
and the value is a string, it used to not work at all, since #7484, it
works somewhat, and this PR make it work some more.

The new cases that are added for `BuiltPath` contexts:

- Fixed input- or content-addressed derivation:

  ```
  nix-repl> hello.out.outPath
  "/nix/store/jppfl2bp1zhx8sgs2mgifmsx6dv16mv2-hello-2.12"

  nix-repl> :p builtins.getContext hello.out.outPath
  { "/nix/store/c7jrxqjhdda93lhbkanqfs07x2bzazbm-hello-2.12.drv" = { outputs = [ "out" ]; }; }

  The string matches the specified single output of that derivation, so
  it should also be valid.

- Floating content-addressed derivation:

  ```
  nix-repl> (hello.overrideAttrs (_: { __contentAddressed = true; })).out.outPath
  "/1a08j26xqc0zm8agps8anxpjji410yvsx4pcgyn4bfan1ddkx2g0"

  nix-repl> :p builtins.getContext (hello.overrideAttrs (_: { __contentAddressed = true; })).out.outPath
  { "/nix/store/qc645pyf9wl37c6qvqzaqkwsm1gp48al-hello-2.12.drv" = { outputs = [ "out" ]; }; }
  ```

  The string is not a path but a placeholder, however it also matches
  the context, and because it is a CA derivation we have no better
  option. This should also be valid.

We may also want to think about richer attrset based values (also
discussed in that issue and #6507), but this change "completes" our
string-based building blocks, from which the others can be desugared
into or at least described/document/taught in terms of.

Progress towards #7417

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
This commit is contained in:
John Ericson 2023-01-10 17:18:59 -05:00
parent 5a23b80b0a
commit d2162e7acd
6 changed files with 110 additions and 26 deletions

View file

@ -46,7 +46,15 @@ std::pair<Value *, PosIdx> InstallableAttrPath::toValue(EvalState & state)
DerivedPathsWithInfo InstallableAttrPath::toDerivedPaths() DerivedPathsWithInfo InstallableAttrPath::toDerivedPaths()
{ {
auto v = toValue(*state).first; auto [v, pos] = toValue(*state);
if (std::optional derivedPathWithInfo = trySinglePathToDerivedPaths(
*v,
pos,
fmt("while evaluating the attribute '%s'", attrPath)))
{
return { *derivedPathWithInfo };
}
Bindings & autoArgs = *cmd.getAutoArgs(*state); Bindings & autoArgs = *cmd.getAutoArgs(*state);

View file

@ -95,31 +95,13 @@ DerivedPathsWithInfo InstallableFlake::toDerivedPaths()
// FIXME: use eval cache? // FIXME: use eval cache?
auto v = attr->forceValue(); auto v = attr->forceValue();
if (v.type() == nPath) { if (std::optional derivedPathWithInfo = trySinglePathToDerivedPaths(
auto storePath = v.path().fetchToStore(state->store); v,
return {{ noPos,
.path = DerivedPath::Opaque { fmt("while evaluating the flake output attribute '%s'", attrPath)))
.path = std::move(storePath), {
}, return { *derivedPathWithInfo };
.info = make_ref<ExtraPathInfo>(),
}};
} }
else if (v.type() == nString) {
NixStringContext context;
auto s = state->forceString(v, context, noPos, fmt("while evaluating the flake output attribute '%s'", attrPath));
auto storePath = state->store->maybeParseStorePath(s);
if (storePath && context.count(NixStringContextElem::Opaque { .path = *storePath })) {
return {{
.path = DerivedPath::Opaque {
.path = std::move(*storePath),
},
.info = make_ref<ExtraPathInfo>(),
}};
} else
throw Error("flake output attribute '%s' evaluates to the string '%s' which is not a store path", attrPath, s);
}
else else
throw Error("flake output attribute '%s' is not a derivation or path", attrPath); throw Error("flake output attribute '%s' is not a derivation or path", attrPath);
} }

View file

@ -41,4 +41,26 @@ ref<InstallableValue> InstallableValue::require(ref<Installable> installable)
return ref { castedInstallable }; return ref { castedInstallable };
} }
std::optional<DerivedPathWithInfo> InstallableValue::trySinglePathToDerivedPaths(Value & v, const PosIdx pos, std::string_view errorCtx)
{
if (v.type() == nPath) {
auto storePath = v.path().fetchToStore(state->store);
return {{
.path = DerivedPath::Opaque {
.path = std::move(storePath),
},
.info = make_ref<ExtraPathInfo>(),
}};
}
else if (v.type() == nString) {
return {{
.path = state->coerceToDerivedPath(pos, v, errorCtx),
.info = make_ref<ExtraPathInfo>(),
}};
}
else return std::nullopt;
}
} }

View file

@ -98,6 +98,24 @@ struct InstallableValue : Installable
static InstallableValue & require(Installable & installable); static InstallableValue & require(Installable & installable);
static ref<InstallableValue> require(ref<Installable> installable); static ref<InstallableValue> require(ref<Installable> installable);
protected:
/**
* Handles either a plain path, or a string with a single string
* context elem in the right format. The latter case is handled by
* `EvalState::coerceToDerivedPath()`; see it for details.
*
* @param v Value that is hopefully a string or path per the above.
*
* @param pos Position of value to aid with diagnostics.
*
* @param errorCtx Arbitrary message for use in potential error message when something is wrong with `v`.
*
* @result A derived path (with empty info, for now) if the value
* matched the above criteria.
*/
std::optional<DerivedPathWithInfo> trySinglePathToDerivedPaths(Value & v, const PosIdx pos, std::string_view errorCtx);
}; };
} }

View file

@ -57,6 +57,30 @@ nix build -f multiple-outputs.nix --json 'e^*' --no-link | jq --exit-status '
(.outputs | keys == ["a_a", "b", "c"])) (.outputs | keys == ["a_a", "b", "c"]))
' '
# test buidling from non-drv attr path
nix build -f multiple-outputs.nix --json 'e.a_a.outPath' --no-link | jq --exit-status '
(.[0] |
(.drvPath | match(".*multiple-outputs-e.drv")) and
(.outputs | keys == ["a_a"]))
'
# Illegal type of string context
expectStderr 1 nix build -f multiple-outputs.nix 'e.a_a.drvPath' \
| grepQuiet "has a context which refers to a complete source and binary closure."
# No string context
expectStderr 1 nix build --expr '""' --no-link \
| grepQuiet "has 0 entries in its context. It should only have exactly one entry"
# Too much string context
expectStderr 1 nix build --impure --expr 'with (import ./multiple-outputs.nix).e.a_a; "${drvPath}${outPath}"' --no-link \
| grepQuiet "has 2 entries in its context. It should only have exactly one entry"
nix build --impure --json --expr 'builtins.unsafeDiscardOutputDependency (import ./multiple-outputs.nix).e.a_a.drvPath' --no-link | jq --exit-status '
(.[0] | .path | match(".*multiple-outputs-e.drv"))
'
# Test building from raw store path to drv not expression. # Test building from raw store path to drv not expression.
drv=$(nix eval -f multiple-outputs.nix --raw a.drvPath) drv=$(nix eval -f multiple-outputs.nix --raw a.drvPath)

View file

@ -41,10 +41,27 @@ cat > $flake1Dir/flake.nix <<EOF
a8 = builtins.storePath $dep; a8 = builtins.storePath $dep;
a9 = "$dep"; a9 = "$dep";
drvCall = with import ./config.nix; mkDerivation {
name = "simple";
builder = ./simple.builder.sh;
PATH = "";
goodPath = path;
};
a10 = builtins.unsafeDiscardOutputDependency self.drvCall.drvPath;
a11 = self.drvCall.drvPath;
a12 = self.drvCall.outPath;
a13 = "\${self.drvCall.drvPath}\${self.drvCall.outPath}";
}; };
} }
EOF EOF
cp ../simple.nix ../simple.builder.sh ../config.nix $flake1Dir/
echo bar > $flake1Dir/foo echo bar > $flake1Dir/foo
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a1 nix build --json --out-link $TEST_ROOT/result $flake1Dir#a1
@ -63,4 +80,17 @@ nix build --json --out-link $TEST_ROOT/result $flake1Dir#a6
nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a8 nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a8
diff common.sh $TEST_ROOT/result diff common.sh $TEST_ROOT/result
(! nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a9) expectStderr 1 nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a9 \
| grepQuiet "has 0 entries in its context. It should only have exactly one entry"
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a10
[[ $(readlink -e $TEST_ROOT/result) = *simple.drv ]]
expectStderr 1 nix build --json --out-link $TEST_ROOT/result $flake1Dir#a11 \
| grepQuiet "has a context which refers to a complete source and binary closure"
nix build --json --out-link $TEST_ROOT/result $flake1Dir#a12
[[ -e $TEST_ROOT/result/hello ]]
expectStderr 1 nix build --impure --json --out-link $TEST_ROOT/result $flake1Dir#a13 \
| grepQuiet "has 2 entries in its context. It should only have exactly one entry"