4 files changed, 104 insertions, 105 deletions

diff --git a/crates/assists/src/handlers/generate_from_impl_for_enum.rs b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
index f6febd3aa..d9388a737 100644
--- a/crates/assists/src/handlers/generate_from_impl_for_enum.rs
+++ b/crates/assists/src/handlers/generate_from_impl_for_enum.rs
@@ -1,15 +1,9 @@
-use ast::GenericParamsOwner;
 use ide_db::helpers::FamousDefs;
 use ide_db::RootDatabase;
-use itertools::Itertools;
-use stdx::format_to;
-use syntax::{
-    ast::{self, AstNode, NameOwner},
-    SmolStr,
-};
+use syntax::ast::{self, AstNode, NameOwner};
 use test_utils::mark;
 
-use crate::{AssistContext, AssistId, AssistKind, Assists};
+use crate::{utils::generate_trait_impl_text, AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: generate_from_impl_for_enum
 //
@@ -31,8 +25,7 @@ use crate::{AssistContext, AssistId, AssistKind, Assists};
 pub(crate) fn generate_from_impl_for_enum(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let variant = ctx.find_node_at_offset::<ast::Variant>()?;
     let variant_name = variant.name()?;
-    let enum_name = variant.parent_enum().name()?;
-    let enum_type_params = variant.parent_enum().generic_param_list();
+    let enum_ = ast::Adt::Enum(variant.parent_enum());
     let (field_name, field_type) = match variant.kind() {
         ast::StructKind::Tuple(field_list) => {
             if field_list.fields().count() != 1 {
@@ -62,49 +55,27 @@ pub(crate) fn generate_from_impl_for_enum(acc: &mut Assists, ctx: &AssistContext
         target,
         |edit| {
             let start_offset = variant.parent_enum().syntax().text_range().end();
-            let mut buf = String::from("\n\nimpl");
-            if let Some(type_params) = &enum_type_params {
-                format_to!(buf, "{}", type_params.syntax());
-            }
-            format_to!(buf, " From<{}> for {}", field_type.syntax(), enum_name);
-            if let Some(type_params) = enum_type_params {
-                let lifetime_params = type_params
-                    .lifetime_params()
-                    .filter_map(|it| it.lifetime())
-                    .map(|it| SmolStr::from(it.text()));
-                let type_params = type_params
-                    .type_params()
-                    .filter_map(|it| it.name())
-                    .map(|it| SmolStr::from(it.text()));
-
-                let generic_params = lifetime_params.chain(type_params).format(", ");
-                format_to!(buf, "<{}>", generic_params)
-            }
-            if let Some(name) = field_name {
-                format_to!(
-                    buf,
-                    r#" {{
-    fn from({0}: {1}) -> Self {{
+            let from_trait = format!("From<{}>", field_type.syntax());
+            let impl_code = if let Some(name) = field_name {
+                format!(
+                    r#"    fn from({0}: {1}) -> Self {{
         Self::{2} {{ {0} }}
-    }}
-}}"#,
+    }}"#,
                     name.text(),
                     field_type.syntax(),
                     variant_name,
-                );
+                )
             } else {
-                format_to!(
-                    buf,
-                    r#" {{
-    fn from(v: {}) -> Self {{
+                format!(
+                    r#"    fn from(v: {}) -> Self {{
         Self::{}(v)
-    }}
-}}"#,
+    }}"#,
                     field_type.syntax(),
                     variant_name,
-                );
-            }
-            edit.insert(start_offset, buf);
+                )
+            };
+            let from_impl = generate_trait_impl_text(&enum_, &from_trait, &impl_code);
+            edit.insert(start_offset, from_impl);
         },
     )
 }
diff --git a/crates/assists/src/handlers/generate_impl.rs b/crates/assists/src/handlers/generate_impl.rs
index 61d1bd25c..16a600e6f 100644
--- a/crates/assists/src/handlers/generate_impl.rs
+++ b/crates/assists/src/handlers/generate_impl.rs
@@ -1,11 +1,6 @@
-use itertools::Itertools;
-use stdx::format_to;
-use syntax::{
-    ast::{self, AstNode, AttrsOwner, GenericParamsOwner, NameOwner},
-    SmolStr,
-};
+use syntax::ast::{self, AstNode, NameOwner};
 
-use crate::{AssistContext, AssistId, AssistKind, Assists};
+use crate::{utils::generate_impl_text, AssistContext, AssistId, AssistKind, Assists};
 
 // Assist: generate_impl
 //
@@ -36,44 +31,15 @@ pub(crate) fn generate_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<()
         format!("Generate impl for `{}`", name),
         target,
         |edit| {
-            let type_params = nominal.generic_param_list();
             let start_offset = nominal.syntax().text_range().end();
-            let mut buf = String::new();
-            buf.push_str("\n\n");
-            nominal
-                .attrs()
-                .filter(|attr| {
-                    attr.as_simple_call().map(|(name, _arg)| name == "cfg").unwrap_or(false)
-                })
-                .for_each(|attr| buf.push_str(format!("{}\n", attr.to_string()).as_str()));
-
-            buf.push_str("impl");
-            if let Some(type_params) = &type_params {
-                format_to!(buf, "{}", type_params.syntax());
-            }
-            buf.push_str(" ");
-            buf.push_str(name.text());
-            if let Some(type_params) = type_params {
-                let lifetime_params = type_params
-                    .lifetime_params()
-                    .filter_map(|it| it.lifetime())
-                    .map(|it| SmolStr::from(it.text()));
-                let type_params = type_params
-                    .type_params()
-                    .filter_map(|it| it.name())
-                    .map(|it| SmolStr::from(it.text()));
-
-                let generic_params = lifetime_params.chain(type_params).format(", ");
-                format_to!(buf, "<{}>", generic_params)
-            }
             match ctx.config.snippet_cap {
                 Some(cap) => {
-                    buf.push_str(" {\n    $0\n}");
-                    edit.insert_snippet(cap, start_offset, buf);
+                    let snippet = generate_impl_text(&nominal, "    $0");
+                    edit.insert_snippet(cap, start_offset, snippet);
                 }
                 None => {
-                    buf.push_str(" {\n}");
-                    edit.insert(start_offset, buf);
+                    let snippet = generate_impl_text(&nominal, "");
+                    edit.insert(start_offset, snippet);
                 }
             }
         },
@@ -132,6 +98,30 @@ mod tests {
                 $0
             }"#,
         );
+
+        check_assist(
+            generate_impl,
+            r#"
+            struct Defaulted<T = i32> {}$0"#,
+            r#"
+            struct Defaulted<T = i32> {}
+
+            impl<T> Defaulted<T> {
+                $0
+            }"#,
+        );
+
+        check_assist(
+            generate_impl,
+            r#"
+            struct Defaulted<'a, 'b: 'a, T: Debug + Clone + 'a + 'b = String> {}$0"#,
+            r#"
+            struct Defaulted<'a, 'b: 'a, T: Debug + Clone + 'a + 'b = String> {}
+
+            impl<'a, 'b: 'a, T: Debug + Clone + 'a + 'b> Defaulted<'a, 'b, T> {
+                $0
+            }"#,
+        );
     }
 
     #[test]
diff --git a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
index 6aa9d2f2c..c69bc5cac 100644
--- a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -2,8 +2,7 @@ use ide_db::helpers::mod_path_to_ast;
 use ide_db::imports_locator;
 use itertools::Itertools;
 use syntax::{
-    ast::{self, make, AstNode},
-    Direction,
+    ast::{self, make, AstNode, NameOwner},
     SyntaxKind::{IDENT, WHITESPACE},
     TextSize,
 };
@@ -11,7 +10,8 @@ use syntax::{
 use crate::{
     assist_context::{AssistBuilder, AssistContext, Assists},
     utils::{
-        add_trait_assoc_items_to_impl, filter_assoc_items, render_snippet, Cursor, DefaultMethods,
+        add_trait_assoc_items_to_impl, filter_assoc_items, generate_trait_impl_text,
+        render_snippet, Cursor, DefaultMethods,
     },
     AssistId, AssistKind,
 };
@@ -57,8 +57,9 @@ pub(crate) fn replace_derive_with_manual_impl(
     let trait_token = ctx.token_at_offset().find(|t| t.kind() == IDENT && t.text() != "derive")?;
     let trait_path = make::path_unqualified(make::path_segment(make::name_ref(trait_token.text())));
 
-    let annotated_name = attr.syntax().siblings(Direction::Next).find_map(ast::Name::cast)?;
-    let insert_pos = annotated_name.syntax().parent()?.text_range().end();
+    let adt = attr.syntax().parent().and_then(ast::Adt::cast)?;
+    let annotated_name = adt.name()?;
+    let insert_pos = adt.syntax().text_range().end();
 
     let current_module = ctx.sema.scope(annotated_name.syntax()).module()?;
     let current_crate = current_module.krate();
@@ -82,10 +83,10 @@ pub(crate) fn replace_derive_with_manual_impl(
 
     let mut no_traits_found = true;
     for (trait_path, trait_) in found_traits.inspect(|_| no_traits_found = false) {
-        add_assist(acc, ctx, &attr, &trait_path, Some(trait_), &annotated_name, insert_pos)?;
+        add_assist(acc, ctx, &attr, &trait_path, Some(trait_), &adt, &annotated_name, insert_pos)?;
     }
     if no_traits_found {
-        add_assist(acc, ctx, &attr, &trait_path, None, &annotated_name, insert_pos)?;
+        add_assist(acc, ctx, &attr, &trait_path, None, &adt, &annotated_name, insert_pos)?;
     }
     Some(())
 }
@@ -96,6 +97,7 @@ fn add_assist(
     attr: &ast::Attr,
     trait_path: &ast::Path,
     trait_: Option<hir::Trait>,
+    adt: &ast::Adt,
     annotated_name: &ast::Name,
     insert_pos: TextSize,
 ) -> Option<()> {
@@ -112,15 +114,15 @@ fn add_assist(
             let impl_def_with_items =
                 impl_def_from_trait(&ctx.sema, annotated_name, trait_, trait_path);
             update_attribute(builder, &input, &trait_name, &attr);
+            let trait_path = format!("{}", trait_path);
             match (ctx.config.snippet_cap, impl_def_with_items) {
-                (None, _) => builder.insert(
-                    insert_pos,
-                    format!("\n\nimpl {} for {} {{\n\n}}", trait_path, annotated_name),
-                ),
+                (None, _) => {
+                    builder.insert(insert_pos, generate_trait_impl_text(adt, &trait_path, ""))
+                }
                 (Some(cap), None) => builder.insert_snippet(
                     cap,
                     insert_pos,
-                    format!("\n\nimpl {} for {} {{\n    $0\n}}", trait_path, annotated_name),
+                    generate_trait_impl_text(adt, &trait_path, "    $0"),
                 ),
                 (Some(cap), Some((impl_def, first_assoc_item))) => {
                     let mut cursor = Cursor::Before(first_assoc_item.syntax());
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 5dd32aef1..8418e6e12 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -2,6 +2,7 @@
 
 use std::ops;
 
+use ast::TypeBoundsOwner;
 use hir::{Adt, HasSource};
 use ide_db::{helpers::SnippetCap, RootDatabase};
 use itertools::Itertools;
@@ -367,21 +368,56 @@ pub(crate) fn find_impl_block_end(impl_def: ast::Impl, buf: &mut String) -> Opti
 // Generates the surrounding `impl Type { <code> }` including type and lifetime
 // parameters
 pub(crate) fn generate_impl_text(adt: &ast::Adt, code: &str) -> String {
-    let type_params = adt.generic_param_list();
+    generate_impl_text_inner(adt, None, code)
+}
+
+// Generates the surrounding `impl <trait> for Type { <code> }` including type
+// and lifetime parameters
+pub(crate) fn generate_trait_impl_text(adt: &ast::Adt, trait_text: &str, code: &str) -> String {
+    generate_impl_text_inner(adt, Some(trait_text), code)
+}
+
+fn generate_impl_text_inner(adt: &ast::Adt, trait_text: Option<&str>, code: &str) -> String {
+    let generic_params = adt.generic_param_list();
     let mut buf = String::with_capacity(code.len());
-    buf.push_str("\n\nimpl");
-    if let Some(type_params) = &type_params {
-        format_to!(buf, "{}", type_params.syntax());
+    buf.push_str("\n\n");
+    adt.attrs()
+        .filter(|attr| attr.as_simple_call().map(|(name, _arg)| name == "cfg").unwrap_or(false))
+        .for_each(|attr| buf.push_str(format!("{}\n", attr.to_string()).as_str()));
+    buf.push_str("impl");
+    if let Some(generic_params) = &generic_params {
+        let lifetimes = generic_params.lifetime_params().map(|lt| format!("{}", lt.syntax()));
+        let type_params = generic_params.type_params().map(|type_param| {
+            let mut buf = String::new();
+            if let Some(it) = type_param.name() {
+                format_to!(buf, "{}", it.syntax());
+            }
+            if let Some(it) = type_param.colon_token() {
+                format_to!(buf, "{} ", it);
+            }
+            if let Some(it) = type_param.type_bound_list() {
+                format_to!(buf, "{}", it.syntax());
+            }
+            buf
+        });
+        let generics = lifetimes.chain(type_params).format(", ");
+        format_to!(buf, "<{}>", generics);
     }
     buf.push(' ');
+    if let Some(trait_text) = trait_text {
+        buf.push_str(trait_text);
+        buf.push_str(" for ");
+    }
     buf.push_str(adt.name().unwrap().text());
-    if let Some(type_params) = type_params {
-        let lifetime_params = type_params
+    if let Some(generic_params) = generic_params {
+        let lifetime_params = generic_params
             .lifetime_params()
             .filter_map(|it| it.lifetime())
             .map(|it| SmolStr::from(it.text()));
-        let type_params =
-            type_params.type_params().filter_map(|it| it.name()).map(|it| SmolStr::from(it.text()));
+        let type_params = generic_params
+            .type_params()
+            .filter_map(|it| it.name())
+            .map(|it| SmolStr::from(it.text()));
         format_to!(buf, "<{}>", lifetime_params.chain(type_params).format(", "))
     }