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feat: In "Fill match arms", allow users to prefer Self to the enum name when possible #19939

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feat: In "Fill match arms", allow users to prefer Self to the enum name when possible #19939

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1 change: 1 addition & 0 deletions crates/ide-assists/src/assist_config.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ pub struct AssistConfig {
pub term_search_borrowck: bool,
pub code_action_grouping: bool,
pub expr_fill_default: ExprFillDefaultMode,
pub prefer_self_ty: bool,
}

impl AssistConfig {
Expand Down
207 changes: 178 additions & 29 deletions crates/ide-assists/src/handlers/add_missing_match_arms.rs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,13 @@
use std::iter::{self, Peekable};

use either::Either;
use hir::{Adt, Crate, HasAttrs, ImportPathConfig, ModuleDef, Semantics, sym};
use hir::{Adt, AsAssocItem, Crate, HasAttrs, ImportPathConfig, ModuleDef, Semantics, sym};
use ide_db::RootDatabase;
use ide_db::assists::ExprFillDefaultMode;
use ide_db::syntax_helpers::suggest_name;
use ide_db::{famous_defs::FamousDefs, helpers::mod_path_to_ast};
use itertools::Itertools;
use syntax::ToSmolStr;
use syntax::ast::edit::IndentLevel;
use syntax::ast::edit_in_place::Indent;
use syntax::ast::syntax_factory::SyntaxFactory;
Expand Down Expand Up @@ -79,12 +80,20 @@ pub(crate) fn add_missing_match_arms(acc: &mut Assists, ctx: &AssistContext<'_>)

let make = SyntaxFactory::with_mappings();

let module = ctx.sema.scope(expr.syntax())?.module();
let scope = ctx.sema.scope(expr.syntax())?;
let module = scope.module();
let self_ty = if ctx.config.prefer_self_ty {
scope
.containing_function()
.and_then(|function| function.as_assoc_item(ctx.db())?.implementing_ty(ctx.db()))
} else {
None
};
let (mut missing_pats, is_non_exhaustive, has_hidden_variants): (
Peekable<Box<dyn Iterator<Item = (ast::Pat, bool)>>>,
bool,
bool,
) = if let Some(enum_def) = resolve_enum_def(&ctx.sema, &expr) {
) = if let Some(enum_def) = resolve_enum_def(&ctx.sema, &expr, self_ty.as_ref()) {
let is_non_exhaustive = enum_def.is_non_exhaustive(ctx.db(), module.krate());

let variants = enum_def.variants(ctx.db());
Expand All @@ -102,16 +111,17 @@ pub(crate) fn add_missing_match_arms(acc: &mut Assists, ctx: &AssistContext<'_>)
})
.filter(|(variant_pat, _)| is_variant_missing(&top_lvl_pats, variant_pat));

let option_enum = FamousDefs(&ctx.sema, module.krate()).core_option_Option().map(lift_enum);
let missing_pats: Box<dyn Iterator<Item = _>> = if Some(enum_def) == option_enum {
let option_enum = FamousDefs(&ctx.sema, module.krate()).core_option_Option();
let missing_pats: Box<dyn Iterator<Item = _>> = if matches!(enum_def, ExtendedEnum::Enum { enum_: e, .. } if Some(e) == option_enum)
{
// Match `Some` variant first.
cov_mark::hit!(option_order);
Box::new(missing_pats.rev())
} else {
Box::new(missing_pats)
};
(missing_pats.peekable(), is_non_exhaustive, has_hidden_variants)
} else if let Some(enum_defs) = resolve_tuple_of_enum_def(&ctx.sema, &expr) {
} else if let Some(enum_defs) = resolve_tuple_of_enum_def(&ctx.sema, &expr, self_ty.as_ref()) {
let is_non_exhaustive =
enum_defs.iter().any(|enum_def| enum_def.is_non_exhaustive(ctx.db(), module.krate()));

Expand Down Expand Up @@ -159,7 +169,9 @@ pub(crate) fn add_missing_match_arms(acc: &mut Assists, ctx: &AssistContext<'_>)
is_non_exhaustive,
has_hidden_variants,
)
} else if let Some((enum_def, len)) = resolve_array_of_enum_def(&ctx.sema, &expr) {
} else if let Some((enum_def, len)) =
resolve_array_of_enum_def(&ctx.sema, &expr, self_ty.as_ref())
{
let is_non_exhaustive = enum_def.is_non_exhaustive(ctx.db(), module.krate());
let variants = enum_def.variants(ctx.db());

Expand Down Expand Up @@ -373,66 +385,81 @@ fn does_pat_match_variant(pat: &Pat, var: &Pat) -> bool {
}
}

#[derive(Eq, PartialEq, Clone, Copy)]
#[derive(Eq, PartialEq, Clone)]
enum ExtendedEnum {
Bool,
Enum(hir::Enum),
Enum { enum_: hir::Enum, use_self: bool },
}

#[derive(Eq, PartialEq, Clone, Copy, Debug)]
enum ExtendedVariant {
True,
False,
Variant(hir::Variant),
Variant { variant: hir::Variant, use_self: bool },
}

impl ExtendedVariant {
fn should_be_hidden(self, db: &RootDatabase, krate: Crate) -> bool {
match self {
ExtendedVariant::Variant(var) => {
ExtendedVariant::Variant { variant: var, .. } => {
var.attrs(db).has_doc_hidden() && var.module(db).krate() != krate
}
_ => false,
}
}
}

fn lift_enum(e: hir::Enum) -> ExtendedEnum {
ExtendedEnum::Enum(e)
}

impl ExtendedEnum {
fn is_non_exhaustive(self, db: &RootDatabase, krate: Crate) -> bool {
fn enum_(
db: &RootDatabase,
enum_: hir::Enum,
enum_ty: &hir::Type,
self_ty: Option<&hir::Type>,
) -> Self {
ExtendedEnum::Enum {
enum_,
use_self: self_ty.is_some_and(|self_ty| self_ty.could_unify_with_deeply(db, enum_ty)),
}
}

fn is_non_exhaustive(&self, db: &RootDatabase, krate: Crate) -> bool {
match self {
ExtendedEnum::Enum(e) => {
ExtendedEnum::Enum { enum_: e, .. } => {
e.attrs(db).by_key(sym::non_exhaustive).exists() && e.module(db).krate() != krate
}
_ => false,
}
}

fn variants(self, db: &RootDatabase) -> Vec<ExtendedVariant> {
match self {
ExtendedEnum::Enum(e) => {
e.variants(db).into_iter().map(ExtendedVariant::Variant).collect::<Vec<_>>()
}
fn variants(&self, db: &RootDatabase) -> Vec<ExtendedVariant> {
match *self {
ExtendedEnum::Enum { enum_: e, use_self } => e
.variants(db)
.into_iter()
.map(|variant| ExtendedVariant::Variant { variant, use_self })
.collect::<Vec<_>>(),
ExtendedEnum::Bool => {
Vec::<ExtendedVariant>::from([ExtendedVariant::True, ExtendedVariant::False])
}
}
}
}

fn resolve_enum_def(sema: &Semantics<'_, RootDatabase>, expr: &ast::Expr) -> Option<ExtendedEnum> {
fn resolve_enum_def(
sema: &Semantics<'_, RootDatabase>,
expr: &ast::Expr,
self_ty: Option<&hir::Type>,
) -> Option<ExtendedEnum> {
sema.type_of_expr(expr)?.adjusted().autoderef(sema.db).find_map(|ty| match ty.as_adt() {
Some(Adt::Enum(e)) => Some(ExtendedEnum::Enum(e)),
Some(Adt::Enum(e)) => Some(ExtendedEnum::enum_(sema.db, e, &ty, self_ty)),
_ => ty.is_bool().then_some(ExtendedEnum::Bool),
})
}

fn resolve_tuple_of_enum_def(
sema: &Semantics<'_, RootDatabase>,
expr: &ast::Expr,
self_ty: Option<&hir::Type>,
) -> Option<Vec<ExtendedEnum>> {
sema.type_of_expr(expr)?
.adjusted()
Expand All @@ -441,7 +468,7 @@ fn resolve_tuple_of_enum_def(
.map(|ty| {
ty.autoderef(sema.db).find_map(|ty| {
match ty.as_adt() {
Some(Adt::Enum(e)) => Some(lift_enum(e)),
Some(Adt::Enum(e)) => Some(ExtendedEnum::enum_(sema.db, e, &ty, self_ty)),
// For now we only handle expansion for a tuple of enums. Here
// we map non-enum items to None and rely on `collect` to
// convert Vec<Option<hir::Enum>> into Option<Vec<hir::Enum>>.
Expand All @@ -456,10 +483,11 @@ fn resolve_tuple_of_enum_def(
fn resolve_array_of_enum_def(
sema: &Semantics<'_, RootDatabase>,
expr: &ast::Expr,
self_ty: Option<&hir::Type>,
) -> Option<(ExtendedEnum, usize)> {
sema.type_of_expr(expr)?.adjusted().as_array(sema.db).and_then(|(ty, len)| {
ty.autoderef(sema.db).find_map(|ty| match ty.as_adt() {
Some(Adt::Enum(e)) => Some((lift_enum(e), len)),
Some(Adt::Enum(e)) => Some((ExtendedEnum::enum_(sema.db, e, &ty, self_ty), len)),
_ => ty.is_bool().then_some((ExtendedEnum::Bool, len)),
})
})
Expand All @@ -474,9 +502,21 @@ fn build_pat(
) -> Option<ast::Pat> {
let db = ctx.db();
match var {
ExtendedVariant::Variant(var) => {
ExtendedVariant::Variant { variant: var, use_self } => {
let edition = module.krate().edition(db);
let path = mod_path_to_ast(&module.find_path(db, ModuleDef::from(var), cfg)?, edition);
let path = if use_self {
make::path_from_segments(
[
make::path_segment(make::name_ref_self_ty()),
make::path_segment(make::name_ref(
&var.name(db).display(db, edition).to_smolstr(),
)),
],
false,
)
} else {
mod_path_to_ast(&module.find_path(db, ModuleDef::from(var), cfg)?, edition)
};
let fields = var.fields(db);
let pat: ast::Pat = match var.kind(db) {
hir::StructKind::Tuple => {
Expand Down Expand Up @@ -509,8 +549,10 @@ fn build_pat(

#[cfg(test)]
mod tests {
use crate::AssistConfig;
use crate::tests::{
check_assist, check_assist_not_applicable, check_assist_target, check_assist_unresolved,
TEST_CONFIG, check_assist, check_assist_not_applicable, check_assist_target,
check_assist_unresolved, check_assist_with_config,
};

use super::add_missing_match_arms;
Expand Down Expand Up @@ -2095,4 +2137,111 @@ fn f() {
"#,
);
}

#[test]
fn prefer_self() {
check_assist_with_config(
add_missing_match_arms,
AssistConfig { prefer_self_ty: true, ..TEST_CONFIG },
r#"
enum Foo {
Bar,
Baz,
}

impl Foo {
fn qux(&self) {
match self {
$0_ => {}
}
}
}
"#,
r#"
enum Foo {
Bar,
Baz,
}

impl Foo {
fn qux(&self) {
match self {
Self::Bar => ${1:todo!()},
Self::Baz => ${2:todo!()},$0
}
}
}
"#,
);
}

#[test]
fn prefer_self_with_generics() {
check_assist_with_config(
add_missing_match_arms,
AssistConfig { prefer_self_ty: true, ..TEST_CONFIG },
r#"
enum Foo<T> {
Bar(T),
Baz,
}

impl<T> Foo<T> {
fn qux(&self) {
match self {
$0_ => {}
}
}
}
"#,
r#"
enum Foo<T> {
Bar(T),
Baz,
}

impl<T> Foo<T> {
fn qux(&self) {
match self {
Self::Bar(${1:_}) => ${2:todo!()},
Self::Baz => ${3:todo!()},$0
}
}
}
"#,
);
check_assist_with_config(
add_missing_match_arms,
AssistConfig { prefer_self_ty: true, ..TEST_CONFIG },
r#"
enum Foo<T> {
Bar(T),
Baz,
}

impl<T> Foo<T> {
fn qux(v: Foo<i32>) {
match v {
$0_ => {}
}
}
}
"#,
r#"
enum Foo<T> {
Bar(T),
Baz,
}

impl<T> Foo<T> {
fn qux(v: Foo<i32>) {
match v {
Foo::Bar(${1:_}) => ${2:todo!()},
Foo::Baz => ${3:todo!()},$0
}
}
}
"#,
);
}
}
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