diff --git a/crates/ide-assists/src/handlers/replace_named_generic_with_impl.rs b/crates/ide-assists/src/handlers/replace_named_generic_with_impl.rs
new file mode 100644
index 00000000000..f32ceb42654
--- /dev/null
+++ b/crates/ide-assists/src/handlers/replace_named_generic_with_impl.rs
@@ -0,0 +1,213 @@
+use hir::Semantics;
+use ide_db::{
+ base_db::{FileId, FileRange},
+ defs::Definition,
+ search::SearchScope,
+ RootDatabase,
+};
+use syntax::{
+ ast::{self, make::impl_trait_type, HasGenericParams, HasName, HasTypeBounds},
+ ted, AstNode,
+};
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: replace_named_generic_with_impl
+//
+// Replaces named generic with an `impl Trait` in function argument.
+//
+// ```
+// fn new
>(location: P) -> Self {}
+// ```
+// ->
+// ```
+// fn new(location: impl AsRef) -> Self {}
+// ```
+pub(crate) fn replace_named_generic_with_impl(
+ acc: &mut Assists,
+ ctx: &AssistContext<'_>,
+) -> Option<()> {
+ // finds `>`
+ let type_param = ctx.find_node_at_offset::()?;
+ // returns `P`
+ let type_param_name = type_param.name()?;
+
+ // The list of type bounds / traits: `AsRef`
+ let type_bound_list = type_param.type_bound_list()?;
+
+ let fn_ = type_param.syntax().ancestors().find_map(ast::Fn::cast)?;
+ let params = fn_
+ .param_list()?
+ .params()
+ .filter_map(|param| {
+ // function parameter type needs to match generic type name
+ if let ast::Type::PathType(path_type) = param.ty()? {
+ let left = path_type.path()?.segment()?.name_ref()?.ident_token()?.to_string();
+ let right = type_param_name.to_string();
+ if left == right {
+ Some(param)
+ } else {
+ None
+ }
+ } else {
+ None
+ }
+ })
+ .collect::>();
+
+ if params.is_empty() {
+ return None;
+ }
+
+ let type_param_hir_def = ctx.sema.to_def(&type_param)?;
+ let type_param_def = Definition::GenericParam(hir::GenericParam::TypeParam(type_param_hir_def));
+
+ if is_referenced_outside(&ctx.sema, type_param_def, &fn_, ctx.file_id()) {
+ return None;
+ }
+
+ let target = type_param.syntax().text_range();
+
+ acc.add(
+ AssistId("replace_named_generic_with_impl", AssistKind::RefactorRewrite),
+ "Replace named generic with impl",
+ target,
+ |edit| {
+ let type_param = edit.make_mut(type_param);
+ let fn_ = edit.make_mut(fn_);
+
+ // get all params
+ let param_types = params
+ .iter()
+ .filter_map(|param| match param.ty() {
+ Some(ast::Type::PathType(param_type)) => Some(edit.make_mut(param_type)),
+ _ => None,
+ })
+ .collect::>();
+
+ if let Some(generic_params) = fn_.generic_param_list() {
+ generic_params.remove_generic_param(ast::GenericParam::TypeParam(type_param));
+ if generic_params.generic_params().count() == 0 {
+ ted::remove(generic_params.syntax());
+ }
+ }
+
+ // get type bounds in signature type: `P` -> `impl AsRef`
+ let new_bounds = impl_trait_type(type_bound_list);
+ for param_type in param_types.iter().rev() {
+ ted::replace(param_type.syntax(), new_bounds.clone_for_update().syntax());
+ }
+ },
+ )
+}
+
+fn is_referenced_outside(
+ sema: &Semantics<'_, RootDatabase>,
+ type_param_def: Definition,
+ fn_: &ast::Fn,
+ file_id: FileId,
+) -> bool {
+ // limit search scope to function body & return type
+ let search_ranges = vec![
+ fn_.body().map(|body| body.syntax().text_range()),
+ fn_.ret_type().map(|ret_type| ret_type.syntax().text_range()),
+ ];
+
+ search_ranges.into_iter().flatten().any(|search_range| {
+ let file_range = FileRange { file_id, range: search_range };
+ !type_param_def.usages(sema).in_scope(SearchScope::file_range(file_range)).all().is_empty()
+ })
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+
+ use crate::tests::{check_assist, check_assist_not_applicable};
+
+ #[test]
+ fn replace_generic_moves_into_function() {
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new(input: T) -> Self {}"#,
+ r#"fn new(input: impl ToString) -> Self {}"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_with_inner_associated_type() {
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new>(input: P) -> Self {}"#,
+ r#"fn new(input: impl AsRef) -> Self {}"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_trait_applies_to_all_matching_params() {
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new(a: T, b: T) -> Self {}"#,
+ r#"fn new(a: impl ToString, b: impl ToString) -> Self {}"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_with_multiple_generic_params() {
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new, T$0: ToString>(t: T, p: P) -> Self {}"#,
+ r#"fn new>(t: impl ToString, p: P) -> Self {}"#,
+ );
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new>(t: T, p: P) -> Self {}"#,
+ r#"fn new>(t: impl ToString, p: P) -> Self {}"#,
+ );
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new(a: A, b: B, c: C) -> Self {}"#,
+ r#"fn new(a: A, b: impl ToString, c: C) -> Self {}"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_with_multiple_trait_bounds() {
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"fn new(p: P) -> Self {}"#,
+ r#"fn new(p: impl Send + Sync) -> Self {}"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_not_applicable_if_param_used_as_return_type() {
+ check_assist_not_applicable(
+ replace_named_generic_with_impl,
+ r#"fn new
(p: P) -> P {}"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_not_applicable_if_param_used_in_fn_body() {
+ check_assist_not_applicable(
+ replace_named_generic_with_impl,
+ r#"fn new
(p: P) { let x: &dyn P = &O; }"#,
+ );
+ }
+
+ #[test]
+ fn replace_generic_ignores_another_function_with_same_param_type() {
+ check_assist(
+ replace_named_generic_with_impl,
+ r#"
+ fn new
(p: P) {}
+ fn hello(p: P) { println!("{:?}", p); }
+ "#,
+ r#"
+ fn new(p: impl Send + Sync) {}
+ fn hello(p: P) { println!("{:?}", p); }
+ "#,
+ );
+ }
+}
diff --git a/crates/ide-assists/src/lib.rs b/crates/ide-assists/src/lib.rs
index fc03903e593..bd282e53434 100644
--- a/crates/ide-assists/src/lib.rs
+++ b/crates/ide-assists/src/lib.rs
@@ -193,6 +193,7 @@ mod handlers {
mod replace_arith_op;
mod introduce_named_generic;
mod replace_let_with_if_let;
+ mod replace_named_generic_with_impl;
mod replace_qualified_name_with_use;
mod replace_string_with_char;
mod replace_turbofish_with_explicit_type;
@@ -299,6 +300,7 @@ mod handlers {
replace_let_with_if_let::replace_let_with_if_let,
replace_method_eager_lazy::replace_with_eager_method,
replace_method_eager_lazy::replace_with_lazy_method,
+ replace_named_generic_with_impl::replace_named_generic_with_impl,
replace_turbofish_with_explicit_type::replace_turbofish_with_explicit_type,
replace_qualified_name_with_use::replace_qualified_name_with_use,
replace_arith_op::replace_arith_with_wrapping,
diff --git a/crates/ide-assists/src/tests/generated.rs b/crates/ide-assists/src/tests/generated.rs
index 0096254ecb7..8a35fd290e6 100644
--- a/crates/ide-assists/src/tests/generated.rs
+++ b/crates/ide-assists/src/tests/generated.rs
@@ -2338,6 +2338,19 @@ fn handle(action: Action) {
)
}
+#[test]
+fn doctest_replace_named_generic_with_impl() {
+ check_doc_test(
+ "replace_named_generic_with_impl",
+ r#####"
+fn new>(location: P) -> Self {}
+"#####,
+ r#####"
+fn new(location: impl AsRef) -> Self {}
+"#####,
+ )
+}
+
#[test]
fn doctest_replace_qualified_name_with_use() {
check_doc_test(
diff --git a/crates/syntax/src/ast/edit_in_place.rs b/crates/syntax/src/ast/edit_in_place.rs
index 995e8d8d152..b3ea6ca8d46 100644
--- a/crates/syntax/src/ast/edit_in_place.rs
+++ b/crates/syntax/src/ast/edit_in_place.rs
@@ -236,6 +236,21 @@ impl ast::GenericParamList {
}
}
+ /// Removes the existing generic param
+ pub fn remove_generic_param(&self, generic_param: ast::GenericParam) {
+ if let Some(previous) = generic_param.syntax().prev_sibling() {
+ if let Some(next_token) = previous.next_sibling_or_token() {
+ ted::remove_all(next_token..=generic_param.syntax().clone().into());
+ }
+ } else if let Some(next) = generic_param.syntax().next_sibling() {
+ if let Some(next_token) = next.prev_sibling_or_token() {
+ ted::remove_all(generic_param.syntax().clone().into()..=next_token);
+ }
+ } else {
+ ted::remove(generic_param.syntax());
+ }
+ }
+
/// Constructs a matching [`ast::GenericArgList`]
pub fn to_generic_args(&self) -> ast::GenericArgList {
let args = self.generic_params().filter_map(|param| match param {
diff --git a/crates/syntax/src/ast/make.rs b/crates/syntax/src/ast/make.rs
index 8d2dc8709ba..3a61fb0a52c 100644
--- a/crates/syntax/src/ast/make.rs
+++ b/crates/syntax/src/ast/make.rs
@@ -232,6 +232,10 @@ pub fn impl_trait(
ast_from_text(&format!("impl{ty_params_str} {trait_} for {ty}{ty_genargs_str} {{}}"))
}
+pub fn impl_trait_type(bounds: ast::TypeBoundList) -> ast::ImplTraitType {
+ ast_from_text(&format!("fn f(x: impl {bounds}) {{}}"))
+}
+
pub fn path_segment(name_ref: ast::NameRef) -> ast::PathSegment {
ast_from_text(&format!("type __ = {name_ref};"))
}