fix: rewrite code_action generate_delegate_trait

crates/hir/src/semantics.rs

@@ -40,8 +40,8 @@ use crate::{
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
     Access, Adjust, Adjustment, AutoBorrow, BindingMode, BuiltinAttr, Callable, ConstParam, Crate,
     DeriveHelper, Field, Function, HasSource, HirFileId, Impl, InFile, Label, LifetimeParam, Local,
-    Macro, Module, ModuleDef, Name, OverloadedDeref, Path, ScopeDef, ToolModule, Trait, Type,
+    Macro, Module, ModuleDef, Name, OverloadedDeref, Path, ScopeDef, Struct, ToolModule, Trait,
-    TypeAlias, TypeParam, VariantDef,
+    Type, TypeAlias, TypeParam, VariantDef,
 };
 
 pub enum DescendPreference {
@@ -229,6 +229,14 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn to_module_defs(&self, file: FileId) -> impl Iterator<Item = Module> {
         self.imp.to_module_def(file)
     }
+
+    pub fn to_struct_def(&self, s: &ast::Struct) -> Option<Struct> {
+        self.imp.to_def(s).map(Struct::from)
+    }
+
+    pub fn to_impl_def(&self, i: &ast::Impl) -> Option<Impl> {
+        self.imp.to_def(i).map(Impl::from)
+    }
 }
 
 impl<'db> SemanticsImpl<'db> {

crates/ide-assists/src/tests/generated.rs

@@ -1153,7 +1153,7 @@ impl SomeTrait for B {
     }
 
     fn method_(&mut self) -> bool {
-        <A as SomeTrait>::method_( &mut self.a )
+        <A as SomeTrait>::method_(&mut self.a)
     }
 }
 "#####,

crates/ide-assists/src/utils/suggest_name.rs

@@ -58,6 +58,32 @@ const USELESS_METHODS: &[&str] = &[
     "into_future",
 ];
 
+pub(crate) fn for_unique_generic_name(
+    name: &str,
+    existing_params: &ast::GenericParamList,
+) -> SmolStr {
+    let param_names = existing_params
+        .generic_params()
+        .map(|param| match param {
+            ast::GenericParam::TypeParam(t) => t.name().unwrap().to_string(),
+            p => p.to_string(),
+        })
+        .collect_vec();
+    let mut name = name.to_string();
+    let base_len = name.len();
+    // 4*len bytes for base, and 2 bytes for 2 digits
+    name.reserve(4 * base_len + 2);
+
+    let mut count = 0;
+    while param_names.contains(&name) {
+        name.truncate(base_len);
+        name.push_str(&count.to_string());
+        count += 1;
+    }
+
+    name.into()
+}
+
 pub(crate) fn for_generic_parameter(ty: &ast::ImplTraitType) -> SmolStr {
     let c = ty
         .type_bound_list()

crates/ide-db/src/path_transform.rs

@@ -82,6 +82,34 @@ impl<'a> PathTransform<'a> {
         }
     }
 
+    pub fn impl_transformation(
+        target_scope: &'a SemanticsScope<'a>,
+        source_scope: &'a SemanticsScope<'a>,
+        impl_: hir::Impl,
+        generic_arg_list: ast::GenericArgList,
+    ) -> PathTransform<'a> {
+        PathTransform {
+            source_scope,
+            target_scope,
+            generic_def: Some(impl_.into()),
+            substs: get_type_args_from_arg_list(generic_arg_list).unwrap_or_default(),
+        }
+    }
+
+    pub fn adt_transformation(
+        target_scope: &'a SemanticsScope<'a>,
+        source_scope: &'a SemanticsScope<'a>,
+        adt: hir::Adt,
+        generic_arg_list: ast::GenericArgList,
+    ) -> PathTransform<'a> {
+        PathTransform {
+            source_scope,
+            target_scope,
+            generic_def: Some(adt.into()),
+            substs: get_type_args_from_arg_list(generic_arg_list).unwrap_or_default(),
+        }
+    }
+
     pub fn generic_transformation(
         target_scope: &'a SemanticsScope<'a>,
         source_scope: &'a SemanticsScope<'a>,

crates/syntax/src/ast/edit_in_place.rs

@@ -13,7 +13,7 @@ use crate::{
     SyntaxNode, SyntaxToken,
 };
 
-use super::{HasArgList, HasName};
+use super::{GenericParam, HasArgList, HasName};
 
 pub trait GenericParamsOwnerEdit: ast::HasGenericParams {
     fn get_or_create_generic_param_list(&self) -> ast::GenericParamList;
@@ -272,6 +272,36 @@ impl ast::GenericParamList {
         }
     }
 
+    /// Find the params corresponded to generic arg
+    pub fn find_generic_arg(&self, generic_arg: &ast::GenericArg) -> Option<GenericParam> {
+        self.generic_params().find_map(move |param| match (&param, &generic_arg) {
+            (ast::GenericParam::LifetimeParam(a), ast::GenericArg::LifetimeArg(b)) => {
+                (a.lifetime()?.lifetime_ident_token()?.text()
+                    == b.lifetime()?.lifetime_ident_token()?.text())
+                .then_some(param)
+            }
+            (ast::GenericParam::TypeParam(a), ast::GenericArg::TypeArg(b)) => {
+                debug_assert_eq!(b.syntax().first_token(), b.syntax().last_token());
+                (a.name()?.text() == b.syntax().first_token()?.text()).then_some(param)
+            }
+            (ast::GenericParam::ConstParam(a), ast::GenericArg::TypeArg(b)) => {
+                debug_assert_eq!(b.syntax().first_token(), b.syntax().last_token());
+                (a.name()?.text() == b.syntax().first_token()?.text()).then_some(param)
+            }
+            _ => None,
+        })
+    }
+
+    /// Removes the corresponding generic arg
+    pub fn remove_generic_arg(&self, generic_arg: &ast::GenericArg) -> Option<GenericParam> {
+        let param_to_remove = self.find_generic_arg(generic_arg);
+
+        if let Some(param) = &param_to_remove {
+            self.remove_generic_param(param.clone());
+        }
+        param_to_remove
+    }
+
     /// Constructs a matching [`ast::GenericArgList`]
     pub fn to_generic_args(&self) -> ast::GenericArgList {
         let args = self.generic_params().filter_map(|param| match param {
@@ -300,6 +330,20 @@ impl ast::WhereClause {
         }
         ted::append_child(self.syntax(), predicate.syntax());
     }
+
+    pub fn remove_predicate(&self, predicate: ast::WherePred) {
+        if let Some(previous) = predicate.syntax().prev_sibling() {
+            if let Some(next_token) = previous.next_sibling_or_token() {
+                ted::remove_all(next_token..=predicate.syntax().clone().into());
+            }
+        } else if let Some(next) = predicate.syntax().next_sibling() {
+            if let Some(next_token) = next.prev_sibling_or_token() {
+                ted::remove_all(predicate.syntax().clone().into()..=next_token);
+            }
+        } else {
+            ted::remove(predicate.syntax());
+        }
+    }
 }
 
 impl ast::TypeParam {

crates/syntax/src/ast/make.rs

@@ -207,10 +207,28 @@ fn merge_gen_params(
         (None, Some(bs)) => Some(bs),
         (Some(ps), None) => Some(ps),
         (Some(ps), Some(bs)) => {
-            for b in bs.generic_params() {
+            // make sure lifetime is placed before other generic params
-                ps.add_generic_param(b);
+            let generic_params = ps.generic_params().merge_by(bs.generic_params(), |_, b| {
-            }
+                !matches!(b, ast::GenericParam::LifetimeParam(_))
-            Some(ps)
+            });
+            Some(generic_param_list(generic_params))
+        }
+    }
+}
+
+fn merge_where_clause(
+    ps: Option<ast::WhereClause>,
+    bs: Option<ast::WhereClause>,
+) -> Option<ast::WhereClause> {
+    match (ps, bs) {
+        (None, None) => None,
+        (None, Some(bs)) => Some(bs),
+        (Some(ps), None) => Some(ps),
+        (Some(ps), Some(bs)) => {
+            let preds = where_clause(std::iter::empty()).clone_for_update();
+            ps.predicates().for_each(|p| preds.add_predicate(p));
+            bs.predicates().for_each(|p| preds.add_predicate(p));
+            Some(preds)
         }
     }
 }
@@ -251,9 +269,9 @@ pub fn impl_(
 pub fn impl_trait(
     is_unsafe: bool,
     trait_gen_params: Option<ast::GenericParamList>,
-    trait_gen_args: Option<ast::GenericParamList>,
+    trait_gen_args: Option<ast::GenericArgList>,
     type_gen_params: Option<ast::GenericParamList>,
-    type_gen_args: Option<ast::GenericParamList>,
+    type_gen_args: Option<ast::GenericArgList>,
     is_negative: bool,
     path_type: ast::Type,
     ty: ast::Type,
@@ -262,15 +280,9 @@ pub fn impl_trait(
     body: Option<Vec<either::Either<ast::Attr, ast::AssocItem>>>,
 ) -> ast::Impl {
     let is_unsafe = if is_unsafe { "unsafe " } else { "" };
-    let ty_gen_args = match merge_gen_params(type_gen_params.clone(), type_gen_args) {
-        Some(pars) => pars.to_generic_args().to_string(),
-        None => String::new(),
-    };
 
-    let tr_gen_args = match merge_gen_params(trait_gen_params.clone(), trait_gen_args) {
+    let trait_gen_args = trait_gen_args.map(|args| args.to_string()).unwrap_or_default();
-        Some(pars) => pars.to_generic_args().to_string(),
+    let type_gen_args = type_gen_args.map(|args| args.to_string()).unwrap_or_default();
-        None => String::new(),
-    };
 
     let gen_params = match merge_gen_params(trait_gen_params, type_gen_params) {
         Some(pars) => pars.to_string(),
@@ -279,25 +291,15 @@ pub fn impl_trait(
 
     let is_negative = if is_negative { "! " } else { "" };
 
-    let where_clause = match (ty_where_clause, trait_where_clause) {
+    let where_clause = merge_where_clause(ty_where_clause, trait_where_clause)
-        (None, None) => " ".to_string(),
+        .map_or_else(|| " ".to_string(), |wc| format!("\n{}\n", wc));
-        (None, Some(tr)) => format!("\n{}\n", tr).to_string(),
-        (Some(ty), None) => format!("\n{}\n", ty).to_string(),
-        (Some(ty), Some(tr)) => {
-            let updated = ty.clone_for_update();
-            tr.predicates().for_each(|p| {
-                ty.add_predicate(p);
-            });
-            format!("\n{}\n", updated).to_string()
-        }
-    };
 
     let body = match body {
         Some(bd) => bd.iter().map(|elem| elem.to_string()).join(""),
         None => String::new(),
     };
 
-    ast_from_text(&format!("{is_unsafe}impl{gen_params} {is_negative}{path_type}{tr_gen_args} for {ty}{ty_gen_args}{where_clause}{{{}}}" , body))
+    ast_from_text(&format!("{is_unsafe}impl{gen_params} {is_negative}{path_type}{trait_gen_args} for {ty}{type_gen_args}{where_clause}{{{}}}" , body))
 }
 
 pub fn impl_trait_type(bounds: ast::TypeBoundList) -> ast::ImplTraitType {
@@ -922,6 +924,10 @@ pub fn type_param(name: ast::Name, bounds: Option<ast::TypeBoundList>) -> ast::T
     ast_from_text(&format!("fn f<{name}{bounds}>() {{ }}"))
 }
 
+pub fn const_param(name: ast::Name, ty: ast::Type) -> ast::ConstParam {
+    ast_from_text(&format!("fn f<const {name}: {ty}>() {{ }}"))
+}
+
 pub fn lifetime_param(lifetime: ast::Lifetime) -> ast::LifetimeParam {
     ast_from_text(&format!("fn f<{lifetime}>() {{ }}"))
 }
@@ -948,9 +954,7 @@ pub fn turbofish_generic_arg_list(
     ast_from_text(&format!("const S: T::<{args}> = ();"))
 }
 
-pub(crate) fn generic_arg_list(
+pub fn generic_arg_list(args: impl IntoIterator<Item = ast::GenericArg>) -> ast::GenericArgList {
-    args: impl IntoIterator<Item = ast::GenericArg>,
-) -> ast::GenericArgList {
     let args = args.into_iter().join(", ");
     ast_from_text(&format!("const S: T<{args}> = ();"))
 }

crates/syntax/src/ast/node_ext.rs

@@ -572,6 +572,16 @@ impl ast::Item {
     }
 }
 
+impl ast::Type {
+    pub fn generic_arg_list(&self) -> Option<ast::GenericArgList> {
+        if let ast::Type::PathType(path_type) = self {
+            path_type.path()?.segment()?.generic_arg_list()
+        } else {
+            None
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum FieldKind {
     Name(ast::NameRef),