ide_assists/handlers/

inline_type_alias.rs

// Some ideas for future improvements:
// - Support replacing aliases which are used in expressions, e.g. `A::new()`.
// - Remove unused aliases if there are no longer any users, see inline_call.rs.

use hir::{HasSource, PathResolution};
use ide_db::FxHashMap;
use ide_db::{
    defs::Definition, imports::insert_use::remove_use_tree_if_simple, search::FileReference,
};
use itertools::Itertools;
use syntax::ast::syntax_factory::SyntaxFactory;
use syntax::syntax_editor::SyntaxEditor;
use syntax::{
    AstNode, NodeOrToken, SyntaxKind, SyntaxNode, T,
    ast::{self, HasGenericParams, HasName},
};

use crate::{
    AssistId,
    assist_context::{AssistContext, Assists},
};

use super::inline_call::split_refs_and_uses;

// Assist: inline_type_alias_uses
//
// Inline a type alias into all of its uses where possible.
//
// ```
// type $0A = i32;
// fn id(x: A) -> A {
//     x
// };
// fn foo() {
//     let _: A = 3;
// }
// ```
// ->
// ```
//
// fn id(x: i32) -> i32 {
//     x
// };
// fn foo() {
//     let _: i32 = 3;
// }
// ```
pub(crate) fn inline_type_alias_uses(acc: &mut Assists, ctx: &AssistContext<'_, '_>) -> Option<()> {
    let name = ctx.find_node_at_offset::<ast::Name>()?;
    let ast_alias = name.syntax().parent().and_then(ast::TypeAlias::cast)?;

    let hir_alias = ctx.sema.to_def(&ast_alias)?;
    let concrete_type = ast_alias.ty()?;

    let usages = Definition::TypeAlias(hir_alias).usages(&ctx.sema);
    if !usages.at_least_one() {
        return None;
    }

    // until this is ok

    acc.add(
        AssistId::refactor_inline("inline_type_alias_uses"),
        "Inline type alias into all uses",
        name.syntax().text_range(),
        |builder| {
            let usages = usages.all();
            let mut definition_deleted = false;

            let mut inline_refs_for_file = |file_id, refs: Vec<FileReference>| {
                let source = ctx.sema.parse(file_id);
                let editor = builder.make_editor(source.syntax());

                let (path_types, path_type_uses) = split_refs_and_uses(refs, |path_type| {
                    path_type.syntax().ancestors().nth(3).and_then(ast::PathType::cast)
                });
                path_type_uses
                    .iter()
                    .for_each(|use_tree| remove_use_tree_if_simple(use_tree, &editor));

                for (target, replacement) in path_types.into_iter().filter_map(|path_type| {
                    let replacement =
                        inline(&ast_alias, &path_type)?.replace_generic(&concrete_type);
                    let target = path_type.syntax().clone();
                    Some((target, replacement))
                }) {
                    editor.replace(target, replacement);
                }

                if file_id.file_id(ctx.db()) == ctx.vfs_file_id() {
                    editor.delete(ast_alias.syntax());
                    definition_deleted = true;
                }
                builder.add_file_edits(file_id.file_id(ctx.db()), editor);
            };

            for (file_id, refs) in usages.into_iter() {
                inline_refs_for_file(file_id, refs);
            }
            if !definition_deleted {
                let editor = builder.make_editor(ast_alias.syntax());
                editor.delete(ast_alias.syntax());
                builder.add_file_edits(ctx.vfs_file_id(), editor)
            }
        },
    )
}

// Assist: inline_type_alias
//
// Replace a type alias with its concrete type.
//
// ```
// type A<T = u32> = Vec<T>;
//
// fn main() {
//     let a: $0A;
// }
// ```
// ->
// ```
// type A<T = u32> = Vec<T>;
//
// fn main() {
//     let a: Vec<u32>;
// }
// ```
pub(crate) fn inline_type_alias(acc: &mut Assists, ctx: &AssistContext<'_, '_>) -> Option<()> {
    let alias_instance = ctx.find_node_at_offset::<ast::PathType>()?;
    let concrete_type;
    let replacement;
    match alias_instance.path()?.as_single_name_ref() {
        Some(nameref) if nameref.Self_token().is_some() => {
            match ctx.sema.resolve_path(&alias_instance.path()?)? {
                PathResolution::SelfType(imp) => {
                    concrete_type = imp.source(ctx.db())?.value.self_ty()?;
                }
                // FIXME: should also work in ADT definitions
                _ => return None,
            }

            replacement = Replacement::Plain;
        }
        _ => {
            let alias = get_type_alias(ctx, &alias_instance)?;
            concrete_type = alias.ty()?;
            replacement = inline(&alias, &alias_instance)?;
        }
    }

    acc.add(
        AssistId::refactor_inline("inline_type_alias"),
        "Inline type alias",
        alias_instance.syntax().text_range(),
        |builder| {
            let editor = builder.make_editor(alias_instance.syntax());
            let replace = replacement.replace_generic(&concrete_type);
            editor.replace(alias_instance.syntax(), replace);
            builder.add_file_edits(ctx.vfs_file_id(), editor);
        },
    )
}

impl Replacement {
    fn replace_generic(&self, concrete_type: &ast::Type) -> SyntaxNode {
        match self {
            Replacement::Generic { lifetime_map, const_and_type_map } => {
                create_replacement(lifetime_map, const_and_type_map, concrete_type)
            }
            Replacement::Plain => concrete_type.syntax().clone(),
        }
    }
}

enum Replacement {
    Generic { lifetime_map: LifetimeMap, const_and_type_map: ConstAndTypeMap },
    Plain,
}

fn inline(alias_def: &ast::TypeAlias, alias_instance: &ast::PathType) -> Option<Replacement> {
    let repl = if let Some(alias_generics) = alias_def.generic_param_list() {
        if alias_generics.generic_params().next().is_none() {
            cov_mark::hit!(no_generics_params);
            return None;
        }
        let instance_args =
            alias_instance.syntax().descendants().find_map(ast::GenericArgList::cast);

        Replacement::Generic {
            lifetime_map: LifetimeMap::new(&instance_args, &alias_generics)?,
            const_and_type_map: ConstAndTypeMap::new(&instance_args, &alias_generics)?,
        }
    } else {
        Replacement::Plain
    };
    Some(repl)
}

struct LifetimeMap(FxHashMap<String, ast::Lifetime>);

impl LifetimeMap {
    fn new(
        instance_args: &Option<ast::GenericArgList>,
        alias_generics: &ast::GenericParamList,
    ) -> Option<Self> {
        let mut inner = FxHashMap::default();
        let make = SyntaxFactory::without_mappings();
        let wildcard_lifetime = make.lifetime("'_");
        let lifetimes = alias_generics
            .lifetime_params()
            .filter_map(|lp| lp.lifetime())
            .map(|l| l.to_string())
            .collect_vec();

        for lifetime in &lifetimes {
            inner.insert(lifetime.to_string(), wildcard_lifetime.clone());
        }

        if let Some(instance_generic_args_list) = &instance_args {
            for (index, lifetime) in instance_generic_args_list
                .lifetime_args()
                .filter_map(|arg| arg.lifetime())
                .enumerate()
            {
                let key = match lifetimes.get(index) {
                    Some(key) => key,
                    None => {
                        cov_mark::hit!(too_many_lifetimes);
                        return None;
                    }
                };

                inner.insert(key.clone(), lifetime);
            }
        }

        Some(Self(inner))
    }
}

struct ConstAndTypeMap(FxHashMap<String, SyntaxNode>);

impl ConstAndTypeMap {
    fn new(
        instance_args: &Option<ast::GenericArgList>,
        alias_generics: &ast::GenericParamList,
    ) -> Option<Self> {
        let mut inner = FxHashMap::default();
        let instance_generics = generic_args_to_const_and_type_generics(instance_args);
        let alias_generics = generic_param_list_to_const_and_type_generics(alias_generics);

        if instance_generics.len() > alias_generics.len() {
            cov_mark::hit!(too_many_generic_args);
            return None;
        }

        // Any declaration generics that don't have a default value must have one
        // provided by the instance.
        for (i, declaration_generic) in alias_generics.iter().enumerate() {
            let key = declaration_generic.replacement_key()?;

            if let Some(instance_generic) = instance_generics.get(i) {
                inner.insert(key, instance_generic.replacement_value()?);
            } else if let Some(value) = declaration_generic.replacement_value() {
                inner.insert(key, value);
            } else {
                cov_mark::hit!(missing_replacement_param);
                return None;
            }
        }

        Some(Self(inner))
    }
}

/// This doesn't attempt to ensure specified generics are compatible with those
/// required by the type alias, other than lifetimes which must either all be
/// specified or all omitted. It will replace TypeArgs with ConstArgs and vice
/// versa if they're in the wrong position. It supports partially specified
/// generics.
///
/// 1. Map the provided instance's generic args to the type alias's generic
///    params:
///
///    ```ignore
///    type A<'a, const N: usize, T = u64> = &'a [T; N];
///          ^ alias generic params
///    let a: A<100>;
///            ^ instance generic args
///
///    generic['a] = '_ due to omission
///    generic[N] = 100 due to the instance arg
///    generic[T] = u64 due to the default param
///    ```
///
/// 2. Copy the concrete type and substitute in each found mapping:
///
///    ```ignore
///    &'_ [u64; 100]
///    ```
///
/// 3. Remove wildcard lifetimes entirely:
///
///    ```ignore
///    &[u64; 100]
///    ```
fn create_replacement(
    lifetime_map: &LifetimeMap,
    const_and_type_map: &ConstAndTypeMap,
    concrete_type: &ast::Type,
) -> SyntaxNode {
    let (editor, updated_concrete_type) = SyntaxEditor::new(concrete_type.syntax().clone());
    let make = editor.make();
    let mut replacements: Vec<(SyntaxNode, SyntaxNode)> = Vec::new();
    let mut removals: Vec<NodeOrToken<SyntaxNode, _>> = Vec::new();

    for syntax in updated_concrete_type.descendants() {
        if let Some(old_lifetime) = ast::Lifetime::cast(syntax.clone()) {
            if let Some(new_lifetime) = lifetime_map.0.get(&old_lifetime.to_string()) {
                if new_lifetime.text() == "'_" {
                    // Check if this lifetime is inside a LifetimeArg (in angle brackets)
                    if let Some(lifetime_arg) =
                        old_lifetime.syntax().parent().and_then(ast::LifetimeArg::cast)
                    {
                        // Remove LifetimeArg and associated comma/whitespace
                        let lifetime_arg_syntax = lifetime_arg.syntax();
                        removals.push(NodeOrToken::Node(lifetime_arg_syntax.clone()));

                        // Remove comma and whitespace (look forward then backward)
                        let comma_and_ws: Vec<_> = lifetime_arg_syntax
                            .siblings_with_tokens(syntax::Direction::Next)
                            .skip(1)
                            .take_while(|it| it.as_token().is_some())
                            .take_while_inclusive(|it| it.kind() == T![,])
                            .collect();

                        if comma_and_ws.iter().any(|it| it.kind() == T![,]) {
                            removals.extend(comma_and_ws);
                        } else {
                            // No comma after, try before
                            let comma_and_ws: Vec<_> = lifetime_arg_syntax
                                .siblings_with_tokens(syntax::Direction::Prev)
                                .skip(1)
                                .take_while(|it| it.as_token().is_some())
                                .take_while_inclusive(|it| it.kind() == T![,])
                                .collect();
                            removals.extend(comma_and_ws);
                        }
                        continue;
                    }
                    removals.push(NodeOrToken::Node(syntax.clone()));
                    if let Some(ws) = syntax.next_sibling_or_token()
                        && ws.kind() == SyntaxKind::WHITESPACE
                    {
                        removals.push(ws);
                    }
                    continue;
                }

                replacements.push((syntax.clone(), new_lifetime.syntax().clone()));
            }
        } else if let Some(name_ref) = ast::NameRef::cast(syntax.clone()) {
            let Some(replacement_syntax) = const_and_type_map.0.get(&name_ref.to_string()) else {
                continue;
            };
            let new_string = replacement_syntax.to_string();
            let new = if new_string == "_" {
                make.wildcard_pat().syntax().clone()
            } else {
                replacement_syntax.clone()
            };

            replacements.push((syntax.clone(), new));
        }
    }

    // Deduplicate removals to avoid intersecting changes
    removals.sort_by_key(|n| n.text_range().start());
    removals.dedup();

    // Remove GenericArgList entirely if all its args are being removed (avoids empty angle brackets)
    let generic_arg_lists_to_check: Vec<_> =
        updated_concrete_type.descendants().filter_map(ast::GenericArgList::cast).collect();

    for generic_arg_list in generic_arg_lists_to_check {
        let will_be_empty = generic_arg_list.generic_args().all(|arg| match arg {
            ast::GenericArg::LifetimeArg(lt_arg) => removals.iter().any(|removal| {
                if let NodeOrToken::Node(node) = removal { node == lt_arg.syntax() } else { false }
            }),
            _ => false,
        });

        if will_be_empty && generic_arg_list.generic_args().next().is_some() {
            removals.retain(|removal| {
                if let NodeOrToken::Node(node) = removal {
                    !node.ancestors().any(|anc| anc == *generic_arg_list.syntax())
                } else {
                    true
                }
            });
            removals.push(NodeOrToken::Node(generic_arg_list.syntax().clone()));
        }
    }

    for (old, new) in replacements {
        editor.replace(old, new);
    }

    for syntax in removals {
        editor.delete(syntax);
    }
    editor.finish().new_root().clone()
}

fn get_type_alias(ctx: &AssistContext<'_, '_>, path: &ast::PathType) -> Option<ast::TypeAlias> {
    let resolved_path = ctx.sema.resolve_path(&path.path()?)?;

    // We need the generics in the correct order to be able to map any provided
    // instance generics to declaration generics. The `hir::TypeAlias` doesn't
    // keep the order, so we must get the `ast::TypeAlias` from the hir
    // definition.
    if let PathResolution::Def(hir::ModuleDef::TypeAlias(ta)) = resolved_path {
        Some(ctx.sema.source(ta)?.value)
    } else {
        None
    }
}

enum ConstOrTypeGeneric {
    ConstArg(ast::ConstArg),
    TypeArg(ast::TypeArg),
    ConstParam(ast::ConstParam),
    TypeParam(ast::TypeParam),
}

impl ConstOrTypeGeneric {
    fn replacement_key(&self) -> Option<String> {
        // Only params are used as replacement keys.
        match self {
            ConstOrTypeGeneric::ConstParam(cp) => Some(cp.name()?.to_string()),
            ConstOrTypeGeneric::TypeParam(tp) => Some(tp.name()?.to_string()),
            _ => None,
        }
    }

    fn replacement_value(&self) -> Option<SyntaxNode> {
        Some(match self {
            ConstOrTypeGeneric::ConstArg(ca) => ca.expr()?.syntax().clone(),
            ConstOrTypeGeneric::TypeArg(ta) => ta.syntax().clone(),
            ConstOrTypeGeneric::ConstParam(cp) => cp.default_val()?.syntax().clone(),
            ConstOrTypeGeneric::TypeParam(tp) => tp.default_type()?.syntax().clone(),
        })
    }
}

fn generic_param_list_to_const_and_type_generics(
    generics: &ast::GenericParamList,
) -> Vec<ConstOrTypeGeneric> {
    let mut others = Vec::new();

    for param in generics.generic_params() {
        match param {
            ast::GenericParam::LifetimeParam(_) => {}
            ast::GenericParam::ConstParam(cp) => {
                others.push(ConstOrTypeGeneric::ConstParam(cp));
            }
            ast::GenericParam::TypeParam(tp) => others.push(ConstOrTypeGeneric::TypeParam(tp)),
        }
    }

    others
}

fn generic_args_to_const_and_type_generics(
    generics: &Option<ast::GenericArgList>,
) -> Vec<ConstOrTypeGeneric> {
    let mut others = Vec::new();

    // It's fine for there to be no instance generics because the declaration
    // might have default values or they might be inferred.
    if let Some(generics) = generics {
        for arg in generics.generic_args() {
            match arg {
                ast::GenericArg::TypeArg(ta) => {
                    others.push(ConstOrTypeGeneric::TypeArg(ta));
                }
                ast::GenericArg::ConstArg(ca) => {
                    others.push(ConstOrTypeGeneric::ConstArg(ca));
                }
                _ => {}
            }
        }
    }

    others
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::tests::{check_assist, check_assist_not_applicable};

    #[test]
    fn empty_generic_params() {
        cov_mark::check!(no_generics_params);
        check_assist_not_applicable(
            inline_type_alias,
            r#"
type A<> = T;
fn main() {
    let a: $0A<u32>;
}
            "#,
        );
    }

    #[test]
    fn too_many_generic_args() {
        cov_mark::check!(too_many_generic_args);
        check_assist_not_applicable(
            inline_type_alias,
            r#"
type A<T> = T;
fn main() {
    let a: $0A<u32, u64>;
}
            "#,
        );
    }

    #[test]
    fn too_many_lifetimes() {
        cov_mark::check!(too_many_lifetimes);
        check_assist_not_applicable(
            inline_type_alias,
            r#"
type A<'a> = &'a &'b u32;
fn f<'a>() {
    let a: $0A<'a, 'b> = 0;
}
"#,
        );
    }

    // This must be supported in order to support "inline_alias_to_users" or
    // whatever it will be called.
    #[test]
    fn alias_as_expression_ignored() {
        check_assist_not_applicable(
            inline_type_alias,
            r#"
type A = Vec<u32>;
fn main() {
    let a: A = $0A::new();
}
"#,
        );
    }

    #[test]
    fn primitive_arg() {
        check_assist(
            inline_type_alias,
            r#"
type A<T> = T;
fn main() {
    let a: $0A<u32> = 0;
}
"#,
            r#"
type A<T> = T;
fn main() {
    let a: u32 = 0;
}
"#,
        );
    }

    #[test]
    fn no_generic_replacements() {
        check_assist(
            inline_type_alias,
            r#"
type A = Vec<u32>;
fn main() {
    let a: $0A;
}
"#,
            r#"
type A = Vec<u32>;
fn main() {
    let a: Vec<u32>;
}
"#,
        );
    }

    #[test]
    fn param_expression() {
        check_assist(
            inline_type_alias,
            r#"
type A<const N: usize = { 1 }> = [u32; N];
fn main() {
    let a: $0A;
}
"#,
            r#"
type A<const N: usize = { 1 }> = [u32; N];
fn main() {
    let a: [u32; { 1 }];
}
"#,
        );
    }

    #[test]
    fn param_default_value() {
        check_assist(
            inline_type_alias,
            r#"
type A<const N: usize = 1> = [u32; N];
fn main() {
    let a: $0A;
}
"#,
            r#"
type A<const N: usize = 1> = [u32; N];
fn main() {
    let a: [u32; 1];
}
"#,
        );
    }

    #[test]
    fn all_param_types() {
        check_assist(
            inline_type_alias,
            r#"
struct Struct<const C: usize>;
type A<'inner1, 'outer1, Outer1, const INNER1: usize, Inner1: Clone, const OUTER1: usize> = (Struct<INNER1>, Struct<OUTER1>, Outer1, &'inner1 (), Inner1, &'outer1 ());
fn foo<'inner2, 'outer2, Outer2, const INNER2: usize, Inner2, const OUTER2: usize>() {
    let a: $0A<'inner2, 'outer2, Outer2, INNER2, Inner2, OUTER2>;
}
"#,
            r#"
struct Struct<const C: usize>;
type A<'inner1, 'outer1, Outer1, const INNER1: usize, Inner1: Clone, const OUTER1: usize> = (Struct<INNER1>, Struct<OUTER1>, Outer1, &'inner1 (), Inner1, &'outer1 ());
fn foo<'inner2, 'outer2, Outer2, const INNER2: usize, Inner2, const OUTER2: usize>() {
    let a: (Struct<INNER2>, Struct<OUTER2>, Outer2, &'inner2 (), Inner2, &'outer2 ());
}
"#,
        );
    }

    #[test]
    fn omitted_lifetimes() {
        check_assist(
            inline_type_alias,
            r#"
type A<'l, 'r> = &'l &'r u32;
fn main() {
    let a: $0A;
}
"#,
            r#"
type A<'l, 'r> = &'l &'r u32;
fn main() {
    let a: &&u32;
}
"#,
        );
    }

    #[test]
    fn omitted_type() {
        check_assist(
            inline_type_alias,
            r#"
type A<'r, 'l, T = u32> = &'l std::collections::HashMap<&'r str, T>;
fn main() {
    let a: $0A<'_, '_>;
}
"#,
            r#"
type A<'r, 'l, T = u32> = &'l std::collections::HashMap<&'r str, T>;
fn main() {
    let a: &std::collections::HashMap<&str, u32>;
}
"#,
        );
    }

    #[test]
    fn omitted_everything() {
        check_assist(
            inline_type_alias,
            r#"
type A<'r, 'l, T = u32> = &'l std::collections::HashMap<&'r str, T>;
fn main() {
    let v = std::collections::HashMap<&str, u32>;
    let a: $0A = &v;
}
"#,
            r#"
type A<'r, 'l, T = u32> = &'l std::collections::HashMap<&'r str, T>;
fn main() {
    let v = std::collections::HashMap<&str, u32>;
    let a: &std::collections::HashMap<&str, u32> = &v;
}
"#,
        );
    }

    // This doesn't actually cause the GenericArgsList to contain a AssocTypeArg.
    #[test]
    fn arg_associated_type() {
        check_assist(
            inline_type_alias,
            r#"
trait Tra { type Assoc; fn a(); }
struct Str {}
impl Tra for Str {
    type Assoc = u32;
    fn a() {
        type A<T> = Vec<T>;
        let a: $0A<Self::Assoc>;
    }
}
"#,
            r#"
trait Tra { type Assoc; fn a(); }
struct Str {}
impl Tra for Str {
    type Assoc = u32;
    fn a() {
        type A<T> = Vec<T>;
        let a: Vec<Self::Assoc>;
    }
}
"#,
        );
    }

    #[test]
    fn param_default_associated_type() {
        check_assist(
            inline_type_alias,
            r#"
trait Tra { type Assoc; fn a() }
struct Str {}
impl Tra for Str {
    type Assoc = u32;
    fn a() {
        type A<T = Self::Assoc> = Vec<T>;
        let a: $0A;
    }
}
"#,
            r#"
trait Tra { type Assoc; fn a() }
struct Str {}
impl Tra for Str {
    type Assoc = u32;
    fn a() {
        type A<T = Self::Assoc> = Vec<T>;
        let a: Vec<Self::Assoc>;
    }
}
"#,
        );
    }

    #[test]
    fn function_pointer() {
        check_assist(
            inline_type_alias,
            r#"
type A = fn(u32);
fn foo(a: u32) {}
fn main() {
    let a: $0A = foo;
}
"#,
            r#"
type A = fn(u32);
fn foo(a: u32) {}
fn main() {
    let a: fn(u32) = foo;
}
"#,
        );
    }

    #[test]
    fn closure() {
        check_assist(
            inline_type_alias,
            r#"
type A = Box<dyn FnOnce(u32) -> u32>;
fn main() {
    let a: $0A = Box::new(|_| 0);
}
"#,
            r#"
type A = Box<dyn FnOnce(u32) -> u32>;
fn main() {
    let a: Box<dyn FnOnce(u32) -> u32> = Box::new(|_| 0);
}
"#,
        );
    }

    // Type aliases can't be used in traits, but someone might use the assist to
    // fix the error.
    #[test]
    fn bounds() {
        check_assist(
            inline_type_alias,
            r#"type A = std::io::Write; fn f<T>() where T: $0A {}"#,
            r#"type A = std::io::Write; fn f<T>() where T: std::io::Write {}"#,
        );
    }

    #[test]
    fn function_parameter() {
        check_assist(
            inline_type_alias,
            r#"
type A = std::io::Write;
fn f(a: impl $0A) {}
"#,
            r#"
type A = std::io::Write;
fn f(a: impl std::io::Write) {}
"#,
        );
    }

    #[test]
    fn arg_expression() {
        check_assist(
            inline_type_alias,
            r#"
type A<const N: usize> = [u32; N];
fn main() {
    let a: $0A<{ 1 + 1 }>;
}
"#,
            r#"
type A<const N: usize> = [u32; N];
fn main() {
    let a: [u32; { 1 + 1 }];
}
"#,
        )
    }

    #[test]
    fn alias_instance_generic_path() {
        check_assist(
            inline_type_alias,
            r#"
type A<const N: usize> = [u32; N];
fn main() {
    let a: $0A<u32::MAX>;
}
"#,
            r#"
type A<const N: usize> = [u32; N];
fn main() {
    let a: [u32; u32::MAX];
}
"#,
        )
    }

    #[test]
    fn generic_type() {
        check_assist(
            inline_type_alias,
            r#"
type A = String;
fn f(a: Vec<$0A>) {}
"#,
            r#"
type A = String;
fn f(a: Vec<String>) {}
"#,
        );
    }

    #[test]
    fn missing_replacement_param() {
        cov_mark::check!(missing_replacement_param);
        check_assist_not_applicable(
            inline_type_alias,
            r#"
type A<U> = Vec<T>;
fn main() {
    let a: $0A;
}
"#,
        );
    }

    #[test]
    fn full_path_type_is_replaced() {
        check_assist(
            inline_type_alias,
            r#"
mod foo {
    pub type A = String;
}
fn main() {
    let a: foo::$0A;
}
"#,
            r#"
mod foo {
    pub type A = String;
}
fn main() {
    let a: String;
}
"#,
        );
    }

    #[test]
    fn inline_self_type() {
        check_assist(
            inline_type_alias,
            r#"
struct Strukt;

impl Strukt {
    fn new() -> Self$0 {}
}
"#,
            r#"
struct Strukt;

impl Strukt {
    fn new() -> Strukt {}
}
"#,
        );
        check_assist(
            inline_type_alias,
            r#"
struct Strukt<'a, T, const C: usize>(&'a [T; C]);

impl<T, const C: usize> Strukt<'_, T, C> {
    fn new() -> Self$0 {}
}
"#,
            r#"
struct Strukt<'a, T, const C: usize>(&'a [T; C]);

impl<T, const C: usize> Strukt<'_, T, C> {
    fn new() -> Strukt<'_, T, C> {}
}
"#,
        );
        check_assist(
            inline_type_alias,
            r#"
struct Strukt<'a, T, const C: usize>(&'a [T; C]);

trait Tr<'b, T> {}

impl<T, const C: usize> Tr<'static, u8> for Strukt<'_, T, C> {
    fn new() -> Self$0 {}
}
"#,
            r#"
struct Strukt<'a, T, const C: usize>(&'a [T; C]);

trait Tr<'b, T> {}

impl<T, const C: usize> Tr<'static, u8> for Strukt<'_, T, C> {
    fn new() -> Strukt<'_, T, C> {}
}
"#,
        );

        check_assist_not_applicable(
            inline_type_alias,
            r#"
trait Tr {
    fn new() -> Self$0;
}
"#,
        );
    }

    #[test]
    fn inline_types_with_lifetime() {
        check_assist(
            inline_type_alias_uses,
            r#"
struct A<'a, 'b>(pub &'a mut &'b mut ());

type $0T<'a, 'b> = A<'a, 'b>;

fn foo(_: T) {}
"#,
            r#"
struct A<'a, 'b>(pub &'a mut &'b mut ());



fn foo(_: A) {}
"#,
        );
    }

    #[test]
    fn mixed_lifetime_and_type_args() {
        check_assist(
            inline_type_alias,
            r#"
type Foo<'a, T> = Bar<'a, T>;
struct Bar<'a, T>(&'a T);
fn main() {
    let a: $0Foo<u32>;
}
"#,
            r#"
type Foo<'a, T> = Bar<'a, T>;
struct Bar<'a, T>(&'a T);
fn main() {
    let a: Bar<u32>;
}
"#,
        );
    }

    mod inline_type_alias_uses {
        use crate::{handlers::inline_type_alias::inline_type_alias_uses, tests::check_assist};

        #[test]
        fn inline_uses() {
            check_assist(
                inline_type_alias_uses,
                r#"
type $0A = u32;

fn foo() {
    let _: A = 3;
    let _: A = 4;
}
"#,
                r#"


fn foo() {
    let _: u32 = 3;
    let _: u32 = 4;
}
"#,
            );
        }

        #[test]
        fn inline_uses_across_files() {
            check_assist(
                inline_type_alias_uses,
                r#"
//- /lib.rs
mod foo;
type $0T<E> = Vec<E>;
fn f() -> T<&str> {
    vec!["hello"]
}

//- /foo.rs
use super::T;
fn foo() {
    let _: T<i8> = Vec::new();
}
"#,
                r#"
//- /lib.rs
mod foo;

fn f() -> Vec<&str> {
    vec!["hello"]
}

//- /foo.rs
fn foo() {
    let _: Vec<i8> = Vec::new();
}
"#,
            );
        }

        #[test]
        fn inline_uses_across_files_2() {
            check_assist(
                inline_type_alias_uses,
                r#"
//- /lib.rs
mod foo;
type $0I = i32;

//- /foo.rs
use super::I;
fn foo() {
    let _: I = 0;
}
"#,
                r#"
//- /lib.rs
mod foo;


//- /foo.rs
fn foo() {
    let _: i32 = 0;
}
"#,
            );
        }
    }
}