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the "implement missing members" assist's const transformation patched
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ponyii committed Jun 16, 2023
1 parent 8a3c214 commit 7e08933
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Showing 3 changed files with 70 additions and 15 deletions.
35 changes: 35 additions & 0 deletions crates/ide-assists/src/handlers/add_missing_impl_members.rs
Original file line number Diff line number Diff line change
Expand Up @@ -423,8 +423,13 @@ impl<'x, 'y, T, V, U: Default> Trait<'x, 'y, T, V, U> for () {
check_assist(
add_missing_default_members,
r#"
struct Bar<const: N: bool> {
bar: [i32, N]
}
trait Foo<const N: usize, T> {
fn get_n_sq(&self, arg: &T) -> usize { N * N }
fn get_array(&self, arg: Bar<N>) -> [i32; N] { [1; N] }
}
struct S<T> {
Expand All @@ -435,8 +440,13 @@ impl<const X: usize, Y, Z> Foo<X, Z> for S<Y> {
$0
}"#,
r#"
struct Bar<const: N: bool> {
bar: [i32, N]
}
trait Foo<const N: usize, T> {
fn get_n_sq(&self, arg: &T) -> usize { N * N }
fn get_array(&self, arg: Bar<N>) -> [i32; N] { [1; N] }
}
struct S<T> {
Expand All @@ -445,6 +455,31 @@ struct S<T> {
impl<const X: usize, Y, Z> Foo<X, Z> for S<Y> {
$0fn get_n_sq(&self, arg: &Z) -> usize { X * X }
fn get_array(&self, arg: Bar<X>) -> [i32; X] { [1; X] }
}"#,
)
}

#[test]
fn test_const_substitution_2() {
check_assist(
add_missing_default_members,
r#"
trait Foo<const N: usize, const M: usize, T> {
fn get_sum(&self, arg: &T) -> usize { N + M }
}
impl<X> Foo<42, {20 + 22}, X> for () {
$0
}"#,
r#"
trait Foo<const N: usize, const M: usize, T> {
fn get_sum(&self, arg: &T) -> usize { N + M }
}
impl<X> Foo<42, {20 + 22}, X> for () {
$0fn get_sum(&self, arg: &X) -> usize { 42 + {20 + 22} }
}"#,
)
}
Expand Down
3 changes: 1 addition & 2 deletions crates/ide-assists/src/handlers/inline_call.rs
Original file line number Diff line number Diff line change
Expand Up @@ -958,7 +958,6 @@ fn main() {
);
}

// FIXME: const generics aren't being substituted, this is blocked on better support for them
#[test]
fn inline_substitutes_generics() {
check_assist(
Expand All @@ -982,7 +981,7 @@ fn foo<T, const N: usize>() {
fn bar<U, const M: usize>() {}
fn main() {
bar::<usize, N>();
bar::<usize, {0}>();
}
"#,
);
Expand Down
47 changes: 34 additions & 13 deletions crates/ide-db/src/path_transform.rs
Original file line number Diff line number Diff line change
Expand Up @@ -11,12 +11,15 @@ use syntax::{

#[derive(Default)]
struct AstSubsts {
// ast::TypeArgs stands in fact for both type and const params
// as consts declared elsewhere look just like type params.
types_and_consts: Vec<ast::TypeArg>,
types_and_consts: Vec<TypeOrConst>,
lifetimes: Vec<ast::LifetimeArg>,
}

enum TypeOrConst {
Either(ast::TypeArg), // indistinguishable type or const param
Const(ast::ConstArg),
}

type LifetimeName = String;

/// `PathTransform` substitutes path in SyntaxNodes in bulk.
Expand Down Expand Up @@ -125,27 +128,38 @@ impl<'a> PathTransform<'a> {
// the resulting change can be applied correctly.
.zip(self.substs.types_and_consts.iter().map(Some).chain(std::iter::repeat(None)))
.for_each(|(k, v)| match (k.split(db), v) {
(Either::Right(t), Some(v)) => {
(Either::Right(k), Some(TypeOrConst::Either(v))) => {
if let Some(ty) = v.ty() {
type_substs.insert(t, ty.clone());
type_substs.insert(k, ty.clone());
}
}
(Either::Right(t), None) => {
if let Some(default) = t.default(db) {
(Either::Right(k), None) => {
if let Some(default) = k.default(db) {
if let Some(default) =
&default.display_source_code(db, source_module.into(), false).ok()
{
type_substs.insert(t, ast::make::ty(default).clone_for_update());
default_types.push(t);
type_substs.insert(k, ast::make::ty(default).clone_for_update());
default_types.push(k);
}
}
}
(Either::Left(c), Some(v)) => {
(Either::Left(k), Some(TypeOrConst::Either(v))) => {
if let Some(ty) = v.ty() {
const_substs.insert(c, ty.syntax().clone());
const_substs.insert(k, ty.syntax().clone());
}
}
(Either::Left(k), Some(TypeOrConst::Const(v))) => {
if let Some(expr) = v.expr() {
// FIXME: expressions in curly brackets can cause ambiguity after insertion
// (e.g. `N * 2` -> `{1 + 1} * 2`; it's unclear whether `{1 + 1}`
// is a standalone statement or a part of another expresson)
// and sometimes require slight modifications; see
// https://doc.rust-lang.org/reference/statements.html#expression-statements
const_substs.insert(k, expr.syntax().clone());
}
}
(Either::Left(_), None) => (), // FIXME: get default const value
_ => (), // ignore mismatching params
});
let lifetime_substs: FxHashMap<_, _> = self
.generic_def
Expand Down Expand Up @@ -201,6 +215,9 @@ impl<'a> Ctx<'a> {
fn transform_default_type_substs(&self, default_types: Vec<hir::TypeParam>) {
for k in default_types {
let v = self.type_substs.get(&k).unwrap();
// `transform_path` may update a node's parent and that would break the
// tree traversal. Thus all paths in the tree are collected into a vec
// so that such operation is safe.
let paths = postorder(&v.syntax()).filter_map(ast::Path::cast).collect::<Vec<_>>();
for path in paths {
self.transform_path(path);
Expand Down Expand Up @@ -326,8 +343,12 @@ fn get_type_args_from_arg_list(generic_arg_list: ast::GenericArgList) -> Option<
// Const params are marked as consts on definition only,
// being passed to the trait they are indistguishable from type params;
// anyway, we don't really need to distinguish them here.
ast::GenericArg::TypeArg(type_or_const_arg) => {
result.types_and_consts.push(type_or_const_arg)
ast::GenericArg::TypeArg(type_arg) => {
result.types_and_consts.push(TypeOrConst::Either(type_arg))
}
// Some const values are recognized correctly.
ast::GenericArg::ConstArg(const_arg) => {
result.types_and_consts.push(TypeOrConst::Const(const_arg));
}
ast::GenericArg::LifetimeArg(l_arg) => result.lifetimes.push(l_arg),
_ => (),
Expand Down

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