6 files changed, 242 insertions, 30 deletions

diff --git a/crates/assists/src/handlers/add_missing_impl_members.rs b/crates/assists/src/handlers/add_missing_impl_members.rs
index e413505d3..7df05b841 100644
--- a/crates/assists/src/handlers/add_missing_impl_members.rs
+++ b/crates/assists/src/handlers/add_missing_impl_members.rs
@@ -15,7 +15,7 @@ use crate::{
 //
 // ```
 // trait Trait<T> {
-//     Type X;
+//     type X;
 //     fn foo(&self) -> T;
 //     fn bar(&self) {}
 // }
@@ -27,14 +27,16 @@ use crate::{
 // ->
 // ```
 // trait Trait<T> {
-//     Type X;
+//     type X;
 //     fn foo(&self) -> T;
 //     fn bar(&self) {}
 // }
 //
 // impl Trait<u32> for () {
+//     $0type X;
+//
 //     fn foo(&self) -> u32 {
-//         ${0:todo!()}
+//         todo!()
 //     }
 // }
 // ```
@@ -54,13 +56,13 @@ pub(crate) fn add_missing_impl_members(acc: &mut Assists, ctx: &AssistContext) -
 //
 // ```
 // trait Trait {
-//     Type X;
+//     type X;
 //     fn foo(&self);
 //     fn bar(&self) {}
 // }
 //
 // impl Trait for () {
-//     Type X = ();
+//     type X = ();
 //     fn foo(&self) {}<|>
 //
 // }
@@ -68,13 +70,13 @@ pub(crate) fn add_missing_impl_members(acc: &mut Assists, ctx: &AssistContext) -
 // ->
 // ```
 // trait Trait {
-//     Type X;
+//     type X;
 //     fn foo(&self);
 //     fn bar(&self) {}
 // }
 //
 // impl Trait for () {
-//     Type X = ();
+//     type X = ();
 //     fn foo(&self) {}
 //
 //     $0fn bar(&self) {}
diff --git a/crates/assists/src/handlers/extract_module_to_file.rs b/crates/assists/src/handlers/extract_module_to_file.rs
new file mode 100644
index 000000000..50bf67ef7
--- /dev/null
+++ b/crates/assists/src/handlers/extract_module_to_file.rs
@@ -0,0 +1,133 @@
+use ast::edit::IndentLevel;
+use ide_db::base_db::AnchoredPathBuf;
+use syntax::{
+    ast::{self, edit::AstNodeEdit, NameOwner},
+    AstNode,
+};
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: extract_module_to_file
+//
+// This assist extract module to file.
+//
+// ```
+// mod foo {<|>
+//     fn t() {}
+// }
+// ```
+// ->
+// ```
+// mod foo;
+// ```
+pub(crate) fn extract_module_to_file(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let module_ast = ctx.find_node_at_offset::<ast::Module>()?;
+    let module_name = module_ast.name()?;
+
+    let module_def = ctx.sema.to_def(&module_ast)?;
+    let parent_module = module_def.parent(ctx.db())?;
+
+    let module_items = module_ast.item_list()?;
+    let target = module_ast.syntax().text_range();
+    let anchor_file_id = ctx.frange.file_id;
+
+    acc.add(
+        AssistId("extract_module_to_file", AssistKind::RefactorExtract),
+        "Extract module to file",
+        target,
+        |builder| {
+            let path = {
+                let dir = match parent_module.name(ctx.db()) {
+                    Some(name) if !parent_module.is_mod_rs(ctx.db()) => format!("{}/", name),
+                    _ => String::new(),
+                };
+                format!("./{}{}.rs", dir, module_name)
+            };
+            let contents = {
+                let items = module_items.dedent(IndentLevel(1)).to_string();
+                let mut items =
+                    items.trim_start_matches('{').trim_end_matches('}').trim().to_string();
+                if !items.is_empty() {
+                    items.push('\n');
+                }
+                items
+            };
+
+            builder.replace(target, format!("mod {};", module_name));
+
+            let dst = AnchoredPathBuf { anchor: anchor_file_id, path };
+            builder.create_file(dst, contents);
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::check_assist;
+
+    use super::*;
+
+    #[test]
+    fn extract_from_root() {
+        check_assist(
+            extract_module_to_file,
+            r#"
+mod tests {<|>
+    #[test] fn t() {}
+}
+"#,
+            r#"
+//- /main.rs
+mod tests;
+//- /tests.rs
+#[test] fn t() {}
+"#,
+        );
+    }
+
+    #[test]
+    fn extract_from_submodule() {
+        check_assist(
+            extract_module_to_file,
+            r#"
+//- /main.rs
+mod submod;
+//- /submod.rs
+mod inner<|> {
+    fn f() {}
+}
+fn g() {}
+"#,
+            r#"
+//- /submod.rs
+mod inner;
+fn g() {}
+//- /submod/inner.rs
+fn f() {}
+"#,
+        );
+    }
+
+    #[test]
+    fn extract_from_mod_rs() {
+        check_assist(
+            extract_module_to_file,
+            r#"
+//- /main.rs
+mod submodule;
+//- /submodule/mod.rs
+mod inner<|> {
+    fn f() {}
+}
+fn g() {}
+"#,
+            r#"
+//- /submodule/mod.rs
+mod inner;
+fn g() {}
+//- /submodule/inner.rs
+fn f() {}
+"#,
+        );
+    }
+}
diff --git a/crates/assists/src/handlers/extract_variable.rs b/crates/assists/src/handlers/extract_variable.rs
index d2ae137cd..9957012fe 100644
--- a/crates/assists/src/handlers/extract_variable.rs
+++ b/crates/assists/src/handlers/extract_variable.rs
@@ -91,7 +91,7 @@ pub(crate) fn extract_variable(acc: &mut Assists, ctx: &AssistContext) -> Option
             // extra newlines in the indent block
             let text = indent.text();
             if text.starts_with('\n') {
-                buf.push_str("\n");
+                buf.push('\n');
                 buf.push_str(text.trim_start_matches('\n'));
             } else {
                 buf.push_str(text);
diff --git a/crates/assists/src/handlers/invert_if.rs b/crates/assists/src/handlers/invert_if.rs
index 91e2f5c8c..f9c33b3f7 100644
--- a/crates/assists/src/handlers/invert_if.rs
+++ b/crates/assists/src/handlers/invert_if.rs
@@ -78,6 +78,15 @@ mod tests {
     }
 
     #[test]
+    fn invert_if_remove_not_parentheses() {
+        check_assist(
+            invert_if,
+            "fn f() { i<|>f !(x == 3 || x == 4 || x == 5) { 3 * 2 } else { 1 } }",
+            "fn f() { if x == 3 || x == 4 || x == 5 { 1 } else { 3 * 2 } }",
+        )
+    }
+
+    #[test]
     fn invert_if_remove_inequality() {
         check_assist(
             invert_if,
diff --git a/crates/assists/src/handlers/remove_unused_param.rs b/crates/assists/src/handlers/remove_unused_param.rs
index 1ff5e92b0..f72dd49ed 100644
--- a/crates/assists/src/handlers/remove_unused_param.rs
+++ b/crates/assists/src/handlers/remove_unused_param.rs
@@ -2,9 +2,10 @@ use ide_db::{defs::Definition, search::Reference};
 use syntax::{
     algo::find_node_at_range,
     ast::{self, ArgListOwner},
-    AstNode, SyntaxNode, TextRange, T,
+    AstNode, SyntaxKind, SyntaxNode, TextRange, T,
 };
 use test_utils::mark;
+use SyntaxKind::WHITESPACE;
 
 use crate::{
     assist_context::AssistBuilder, utils::next_prev, AssistContext, AssistId, AssistKind, Assists,
@@ -56,7 +57,7 @@ pub(crate) fn remove_unused_param(acc: &mut Assists, ctx: &AssistContext) -> Opt
         "Remove unused parameter",
         param.syntax().text_range(),
         |builder| {
-            builder.delete(range_with_coma(param.syntax()));
+            builder.delete(range_to_remove(param.syntax()));
             for usage in fn_def.usages(&ctx.sema).all() {
                 process_usage(ctx, builder, usage, param_position);
             }
@@ -80,19 +81,34 @@ fn process_usage(
     let arg = call_expr.arg_list()?.args().nth(arg_to_remove)?;
 
     builder.edit_file(usage.file_range.file_id);
-    builder.delete(range_with_coma(arg.syntax()));
+    builder.delete(range_to_remove(arg.syntax()));
 
     Some(())
 }
 
-fn range_with_coma(node: &SyntaxNode) -> TextRange {
-    let up_to = next_prev().find_map(|dir| {
+fn range_to_remove(node: &SyntaxNode) -> TextRange {
+    let up_to_comma = next_prev().find_map(|dir| {
         node.siblings_with_tokens(dir)
             .filter_map(|it| it.into_token())
             .find(|it| it.kind() == T![,])
+            .map(|it| (dir, it))
     });
-    let up_to = up_to.map_or(node.text_range(), |it| it.text_range());
-    node.text_range().cover(up_to)
+    if let Some((dir, token)) = up_to_comma {
+        if node.next_sibling().is_some() {
+            let up_to_space = token
+                .siblings_with_tokens(dir)
+                .skip(1)
+                .take_while(|it| it.kind() == WHITESPACE)
+                .last()
+                .and_then(|it| it.into_token());
+            return node
+                .text_range()
+                .cover(up_to_space.map_or(token.text_range(), |it| it.text_range()));
+        }
+        node.text_range().cover(token.text_range())
+    } else {
+        node.text_range()
+    }
 }
 
 #[cfg(test)]
@@ -119,6 +135,57 @@ fn b() { foo(9, ) }
     }
 
     #[test]
+    fn remove_unused_first_param() {
+        check_assist(
+            remove_unused_param,
+            r#"
+fn foo(<|>x: i32, y: i32) { y; }
+fn a() { foo(1, 2) }
+fn b() { foo(1, 2,) }
+"#,
+            r#"
+fn foo(y: i32) { y; }
+fn a() { foo(2) }
+fn b() { foo(2,) }
+"#,
+        );
+    }
+
+    #[test]
+    fn remove_unused_single_param() {
+        check_assist(
+            remove_unused_param,
+            r#"
+fn foo(<|>x: i32) { 0; }
+fn a() { foo(1) }
+fn b() { foo(1, ) }
+"#,
+            r#"
+fn foo() { 0; }
+fn a() { foo() }
+fn b() { foo( ) }
+"#,
+        );
+    }
+
+    #[test]
+    fn remove_unused_surrounded_by_parms() {
+        check_assist(
+            remove_unused_param,
+            r#"
+fn foo(x: i32, <|>y: i32, z: i32) { x; }
+fn a() { foo(1, 2, 3) }
+fn b() { foo(1, 2, 3,) }
+"#,
+            r#"
+fn foo(x: i32, z: i32) { x; }
+fn a() { foo(1, 3) }
+fn b() { foo(1, 3,) }
+"#,
+        );
+    }
+
+    #[test]
     fn remove_unused_qualified_call() {
         check_assist(
             remove_unused_param,
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 4d6a1956b..cb7a5c104 100644
--- a/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
+++ b/crates/assists/src/handlers/replace_derive_with_manual_impl.rs
@@ -62,21 +62,22 @@ pub(crate) fn replace_derive_with_manual_impl(
     let current_module = ctx.sema.scope(annotated_name.syntax()).module()?;
     let current_crate = current_module.krate();
 
-    let found_traits =
-        imports_locator::find_exact_imports(&ctx.sema, current_crate, trait_token.text())
-            .filter_map(
-                |candidate: either::Either<hir::ModuleDef, hir::MacroDef>| match candidate {
-                    either::Either::Left(hir::ModuleDef::Trait(trait_)) => Some(trait_),
-                    _ => None,
-                },
-            )
-            .flat_map(|trait_| {
-                current_module
-                    .find_use_path(ctx.sema.db, hir::ModuleDef::Trait(trait_))
-                    .as_ref()
-                    .map(mod_path_to_ast)
-                    .zip(Some(trait_))
-            });
+    let found_traits = imports_locator::find_exact_imports(
+        &ctx.sema,
+        current_crate,
+        trait_token.text().to_string(),
+    )
+    .filter_map(|candidate: either::Either<hir::ModuleDef, hir::MacroDef>| match candidate {
+        either::Either::Left(hir::ModuleDef::Trait(trait_)) => Some(trait_),
+        _ => None,
+    })
+    .flat_map(|trait_| {
+        current_module
+            .find_use_path(ctx.sema.db, hir::ModuleDef::Trait(trait_))
+            .as_ref()
+            .map(mod_path_to_ast)
+            .zip(Some(trait_))
+    });
 
     let mut no_traits_found = true;
     for (trait_path, trait_) in found_traits.inspect(|_| no_traits_found = false) {