Merge pull request #19704 from Veykril/push-wrvznvvpvtvp

Add expression fill mode variant for filling with underscore expressions

crates/hir-def/src/nameres/mod_resolution.rs

@@ -86,7 +86,7 @@ impl ModDir {
                 let dir_path = if root_dir_owner {
                     DirPath::empty()
                 } else {
-                    DirPath::new(format!("{}/", name))
+                    DirPath::new(format!("{name}/"))
                 };
                 if let Some(mod_dir) = self.child(dir_path, !root_dir_owner) {
                     return Ok((

crates/hir-expand/src/db.rs

@@ -752,8 +752,7 @@ fn check_tt_count(tt: &tt::TopSubtree) -> Result<(), ExpandResult<()>> {
             err: Some(ExpandError::other(
                 tt.delimiter.open,
                 format!(
-                    "macro invocation exceeds token limit: produced {} tokens, limit is {}",
-                    count, TOKEN_LIMIT,
+                    "macro invocation exceeds token limit: produced {count} tokens, limit is {TOKEN_LIMIT}",
                 ),
             )),
         })

crates/hir-expand/src/lib.rs

@@ -206,8 +206,7 @@ impl ExpandErrorKind {
                     },
                     None => RenderedExpandError {
                         message: format!(
-                            "internal error: proc-macro map is missing error entry for crate {:?}",
-                            def_crate
+                            "internal error: proc-macro map is missing error entry for crate {def_crate:?}"
                         ),
                         error: true,
                         kind: RenderedExpandError::GENERAL_KIND,

crates/ide-assists/src/assist_config.rs

@@ -5,7 +5,7 @@
 //! assists if we are allowed to.
 
 use hir::ImportPathConfig;
-use ide_db::{SnippetCap, imports::insert_use::InsertUseConfig};
+use ide_db::{SnippetCap, assists::ExprFillDefaultMode, imports::insert_use::InsertUseConfig};
 
 use crate::AssistKind;
 
@@ -21,6 +21,7 @@ pub struct AssistConfig {
     pub term_search_fuel: u64,
     pub term_search_borrowck: bool,
     pub code_action_grouping: bool,
+    pub expr_fill_default: ExprFillDefaultMode,
 }
 
 impl AssistConfig {

crates/ide-assists/src/handlers/add_missing_impl_members.rs

@@ -150,6 +150,7 @@ fn add_missing_impl_members_inner(
         let new_impl_def = edit.make_mut(impl_def.clone());
         let first_new_item = add_trait_assoc_items_to_impl(
             &ctx.sema,
+            ctx.config,
             &missing_items,
             trait_,
             &new_impl_def,

crates/ide-assists/src/handlers/add_missing_match_arms.rs

@@ -3,6 +3,7 @@ use std::iter::{self, Peekable};
 use either::Either;
 use hir::{Adt, Crate, HasAttrs, ImportPathConfig, ModuleDef, Semantics, sym};
 use ide_db::RootDatabase;
+use ide_db::assists::ExprFillDefaultMode;
 use ide_db::syntax_helpers::suggest_name;
 use ide_db::{famous_defs::FamousDefs, helpers::mod_path_to_ast};
 use itertools::Itertools;
@@ -216,7 +217,17 @@ pub(crate) fn add_missing_match_arms(acc: &mut Assists, ctx: &AssistContext<'_>)
                     // filter out hidden patterns because they're handled by the catch-all arm
                     !hidden
                 })
-                .map(|(pat, _)| make.match_arm(pat, None, make::ext::expr_todo()));
+                .map(|(pat, _)| {
+                    make.match_arm(
+                        pat,
+                        None,
+                        match ctx.config.expr_fill_default {
+                            ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+                            ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+                            ExprFillDefaultMode::Default => make::ext::expr_todo(),
+                        },
+                    )
+                });
 
             let mut arms: Vec<_> = match_arm_list
                 .arms()
@@ -246,7 +257,15 @@ pub(crate) fn add_missing_match_arms(acc: &mut Assists, ctx: &AssistContext<'_>)
 
             if needs_catch_all_arm && !has_catch_all_arm {
                 cov_mark::hit!(added_wildcard_pattern);
-                let arm = make.match_arm(make.wildcard_pat().into(), None, make::ext::expr_todo());
+                let arm = make.match_arm(
+                    make.wildcard_pat().into(),
+                    None,
+                    match ctx.config.expr_fill_default {
+                        ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+                        ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+                        ExprFillDefaultMode::Default => make::ext::expr_todo(),
+                    },
+                );
                 arms.push(arm);
             }
 

crates/ide-assists/src/handlers/destructure_tuple_binding.rs

@@ -142,7 +142,7 @@ fn collect_data(ident_pat: IdentPat, ctx: &AssistContext<'_>) -> Option<TupleDat
         .map(|(id, ty)| {
             match name_generator.for_type(&ty, ctx.db(), ctx.edition()) {
                 Some(name) => name,
-                None => name_generator.suggest_name(&format!("_{}", id)),
+                None => name_generator.suggest_name(&format!("_{id}")),
             }
             .to_string()
         })

crates/ide-assists/src/handlers/generate_function.rs

@@ -4,6 +4,7 @@ use hir::{
 };
 use ide_db::{
     FileId, FxHashMap, FxHashSet, RootDatabase, SnippetCap,
+    assists::ExprFillDefaultMode,
     defs::{Definition, NameRefClass},
     famous_defs::FamousDefs,
     helpers::is_editable_crate,
@@ -276,7 +277,11 @@ impl FunctionBuilder {
                 target_module,
                 &mut necessary_generic_params,
             );
-            let placeholder_expr = make::ext::expr_todo();
+            let placeholder_expr = match ctx.config.expr_fill_default {
+                ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+                ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+                ExprFillDefaultMode::Default => make::ext::expr_todo(),
+            };
             fn_body = make::block_expr(vec![], Some(placeholder_expr));
         };
 
@@ -331,7 +336,11 @@ impl FunctionBuilder {
         let (generic_param_list, where_clause) =
             fn_generic_params(ctx, necessary_generic_params, &target)?;
 
-        let placeholder_expr = make::ext::expr_todo();
+        let placeholder_expr = match ctx.config.expr_fill_default {
+            ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+            ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+            ExprFillDefaultMode::Default => make::ext::expr_todo(),
+        };
         let fn_body = make::block_expr(vec![], Some(placeholder_expr));
 
         Some(Self {
@@ -444,7 +453,11 @@ fn make_fn_body_as_new_function(
     let adt_info = adt_info.as_ref()?;
 
     let path_self = make::ext::ident_path("Self");
-    let placeholder_expr = make::ext::expr_todo();
+    let placeholder_expr = match ctx.config.expr_fill_default {
+        ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+        ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+        ExprFillDefaultMode::Default => make::ext::expr_todo(),
+    };
     let tail_expr = if let Some(strukt) = adt_info.adt.as_struct() {
         match strukt.kind(ctx.db()) {
             StructKind::Record => {

crates/ide-assists/src/handlers/replace_derive_with_manual_impl.rs

@@ -9,7 +9,7 @@ use syntax::{
 };
 
 use crate::{
-    AssistId,
+    AssistConfig, AssistId,
     assist_context::{AssistContext, Assists, SourceChangeBuilder},
     utils::{
         DefaultMethods, IgnoreAssocItems, add_trait_assoc_items_to_impl, filter_assoc_items,
@@ -128,8 +128,14 @@ fn add_assist(
     acc.add(AssistId::refactor("replace_derive_with_manual_impl"), label, target, |builder| {
         let insert_after = ted::Position::after(builder.make_mut(adt.clone()).syntax());
         let impl_is_unsafe = trait_.map(|s| s.is_unsafe(ctx.db())).unwrap_or(false);
-        let impl_def_with_items =
-            impl_def_from_trait(&ctx.sema, adt, &annotated_name, trait_, replace_trait_path);
+        let impl_def_with_items = impl_def_from_trait(
+            &ctx.sema,
+            ctx.config,
+            adt,
+            &annotated_name,
+            trait_,
+            replace_trait_path,
+        );
         update_attribute(builder, old_derives, old_tree, old_trait_path, attr);
 
         let trait_path = make::ty_path(replace_trait_path.clone());
@@ -217,6 +223,7 @@ fn add_assist(
 
 fn impl_def_from_trait(
     sema: &hir::Semantics<'_, ide_db::RootDatabase>,
+    config: &AssistConfig,
     adt: &ast::Adt,
     annotated_name: &ast::Name,
     trait_: Option<hir::Trait>,
@@ -241,7 +248,7 @@ fn impl_def_from_trait(
     let impl_def = generate_trait_impl(adt, make::ty_path(trait_path.clone()));
 
     let first_assoc_item =
-        add_trait_assoc_items_to_impl(sema, &trait_items, trait_, &impl_def, &target_scope);
+        add_trait_assoc_items_to_impl(sema, config, &trait_items, trait_, &impl_def, &target_scope);
 
     // Generate a default `impl` function body for the derived trait.
     if let ast::AssocItem::Fn(ref func) = first_assoc_item {

crates/ide-assists/src/tests.rs

@@ -4,6 +4,7 @@ use expect_test::expect;
 use hir::Semantics;
 use ide_db::{
     EditionedFileId, FileRange, RootDatabase, SnippetCap,
+    assists::ExprFillDefaultMode,
     base_db::SourceDatabase,
     imports::insert_use::{ImportGranularity, InsertUseConfig},
     source_change::FileSystemEdit,
@@ -35,6 +36,7 @@ pub(crate) const TEST_CONFIG: AssistConfig = AssistConfig {
     term_search_fuel: 400,
     term_search_borrowck: true,
     code_action_grouping: true,
+    expr_fill_default: ExprFillDefaultMode::Todo,
 };
 
 pub(crate) const TEST_CONFIG_NO_GROUPING: AssistConfig = AssistConfig {
@@ -54,6 +56,7 @@ pub(crate) const TEST_CONFIG_NO_GROUPING: AssistConfig = AssistConfig {
     term_search_fuel: 400,
     term_search_borrowck: true,
     code_action_grouping: false,
+    expr_fill_default: ExprFillDefaultMode::Todo,
 };
 
 pub(crate) const TEST_CONFIG_NO_SNIPPET_CAP: AssistConfig = AssistConfig {
@@ -73,6 +76,7 @@ pub(crate) const TEST_CONFIG_NO_SNIPPET_CAP: AssistConfig = AssistConfig {
     term_search_fuel: 400,
     term_search_borrowck: true,
     code_action_grouping: true,
+    expr_fill_default: ExprFillDefaultMode::Todo,
 };
 
 pub(crate) const TEST_CONFIG_IMPORT_ONE: AssistConfig = AssistConfig {
@@ -92,6 +96,7 @@ pub(crate) const TEST_CONFIG_IMPORT_ONE: AssistConfig = AssistConfig {
     term_search_fuel: 400,
     term_search_borrowck: true,
     code_action_grouping: true,
+    expr_fill_default: ExprFillDefaultMode::Todo,
 };
 
 pub(crate) fn with_single_file(text: &str) -> (RootDatabase, EditionedFileId) {

crates/ide-assists/src/utils.rs

@@ -8,6 +8,7 @@ use hir::{
 };
 use ide_db::{
     RootDatabase,
+    assists::ExprFillDefaultMode,
     famous_defs::FamousDefs,
     path_transform::PathTransform,
     syntax_helpers::{node_ext::preorder_expr, prettify_macro_expansion},
@@ -27,7 +28,10 @@ use syntax::{
     ted,
 };
 
-use crate::assist_context::{AssistContext, SourceChangeBuilder};
+use crate::{
+    AssistConfig,
+    assist_context::{AssistContext, SourceChangeBuilder},
+};
 
 mod gen_trait_fn_body;
 pub(crate) mod ref_field_expr;
@@ -174,6 +178,7 @@ pub fn filter_assoc_items(
 /// inserted.
 pub fn add_trait_assoc_items_to_impl(
     sema: &Semantics<'_, RootDatabase>,
+    config: &AssistConfig,
     original_items: &[InFile<ast::AssocItem>],
     trait_: hir::Trait,
     impl_: &ast::Impl,
@@ -219,7 +224,14 @@ pub fn add_trait_assoc_items_to_impl(
         match &item {
             ast::AssocItem::Fn(fn_) if fn_.body().is_none() => {
                 let body = AstNodeEdit::indent(
-                    &make::block_expr(None, Some(make::ext::expr_todo())),
+                    &make::block_expr(
+                        None,
+                        Some(match config.expr_fill_default {
+                            ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+                            ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+                            ExprFillDefaultMode::Default => make::ext::expr_todo(),
+                        }),
+                    ),
                     new_indent_level,
                 );
                 ted::replace(fn_.get_or_create_body().syntax(), body.clone_for_update().syntax())

crates/ide-completion/src/item.rs

@@ -135,7 +135,7 @@ impl fmt::Debug for CompletionItem {
                 },
                 CompletionItemRefMode::Dereference => "*",
             };
-            s.field("ref_match", &format!("{}@{offset:?}", prefix));
+            s.field("ref_match", &format!("{prefix}@{offset:?}"));
         }
         if self.trigger_call_info {
             s.field("trigger_call_info", &true);

crates/ide-db/src/assists.rs

@@ -169,3 +169,15 @@ impl AssistResolveStrategy {
 
 #[derive(Clone, Debug)]
 pub struct GroupLabel(pub String);
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum ExprFillDefaultMode {
+    Todo,
+    Default,
+    Underscore,
+}
+impl Default for ExprFillDefaultMode {
+    fn default() -> Self {
+        Self::Todo
+    }
+}

crates/ide-diagnostics/src/handlers/missing_fields.rs

@@ -5,9 +5,13 @@ use hir::{
     sym,
 };
 use ide_db::{
-    FxHashMap, assists::Assist, famous_defs::FamousDefs,
-    imports::import_assets::item_for_path_search, source_change::SourceChange,
-    syntax_helpers::tree_diff::diff, text_edit::TextEdit,
+    FxHashMap,
+    assists::{Assist, ExprFillDefaultMode},
+    famous_defs::FamousDefs,
+    imports::import_assets::item_for_path_search,
+    source_change::SourceChange,
+    syntax_helpers::tree_diff::diff,
+    text_edit::TextEdit,
     use_trivial_constructor::use_trivial_constructor,
 };
 use stdx::format_to;
@@ -102,8 +106,9 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::MissingFields) -> Option<Vec<Ass
             });
 
             let generate_fill_expr = |ty: &Type| match ctx.config.expr_fill_default {
-                crate::ExprFillDefaultMode::Todo => make::ext::expr_todo(),
-                crate::ExprFillDefaultMode::Default => {
+                ExprFillDefaultMode::Todo => make::ext::expr_todo(),
+                ExprFillDefaultMode::Underscore => make::ext::expr_underscore(),
+                ExprFillDefaultMode::Default => {
                     get_default_constructor(ctx, d, ty).unwrap_or_else(make::ext::expr_todo)
                 }
             };

crates/ide-diagnostics/src/handlers/typed_hole.rs

@@ -1,3 +1,5 @@
+use std::ops::Not;
+
 use hir::{
     ClosureStyle, HirDisplay, ImportPathConfig,
     db::ExpandDatabase,
@@ -60,9 +62,13 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::TypedHole) -> Option<Vec<Assist>
 
     let mut formatter = |_: &hir::Type| String::from("_");
 
-    let assists: Vec<Assist> = paths
+    let assists: Vec<Assist> = d
+        .expected
+        .is_unknown()
+        .not()
+        .then(|| "todo!()".to_owned())
         .into_iter()
-        .filter_map(|path| {
+        .chain(paths.into_iter().filter_map(|path| {
             path.gen_source_code(
                 &scope,
                 &mut formatter,
@@ -75,7 +81,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::TypedHole) -> Option<Vec<Assist>
                 ctx.display_target,
             )
             .ok()
-        })
+        }))
         .unique()
         .map(|code| Assist {
             id: AssistId::quick_fix("typed-hole"),
@@ -95,9 +101,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::TypedHole) -> Option<Vec<Assist>
 
 #[cfg(test)]
 mod tests {
-    use crate::tests::{
-        check_diagnostics, check_fixes_unordered, check_has_fix, check_has_single_fix,
-    };
+    use crate::tests::{check_diagnostics, check_fixes_unordered, check_has_fix};
 
     #[test]
     fn unknown() {
@@ -119,9 +123,9 @@ fn main() {
     if _ {}
      //^ 💡 error: invalid `_` expression, expected type `bool`
     let _: fn() -> i32 = _;
-                       //^ error: invalid `_` expression, expected type `fn() -> i32`
+                       //^ 💡 error: invalid `_` expression, expected type `fn() -> i32`
     let _: fn() -> () = _; // FIXME: This should trigger an assist because `main` matches via *coercion*
-                      //^ error: invalid `_` expression, expected type `fn()`
+                      //^ 💡 error: invalid `_` expression, expected type `fn()`
 }
 "#,
         );
@@ -147,7 +151,7 @@ fn main() {
 fn main() {
     let mut x = t();
     x = _;
-      //^ error: invalid `_` expression, expected type `&str`
+      //^ 💡 error: invalid `_` expression, expected type `&str`
     x = "";
 }
 fn t<T>() -> T { loop {} }
@@ -308,7 +312,7 @@ fn main() {
 
     #[test]
     fn ignore_impl_func_with_incorrect_return() {
-        check_has_single_fix(
+        check_fixes_unordered(
             r#"
 struct Bar {}
 trait Foo {
@@ -323,7 +327,8 @@ fn main() {
     let a: i32 = 1;
     let c: Bar = _$0;
 }"#,
-            r#"
+            vec![
+                r#"
 struct Bar {}
 trait Foo {
     type Res;
@@ -337,6 +342,21 @@ fn main() {
     let a: i32 = 1;
     let c: Bar = Bar {  };
 }"#,
+                r#"
+struct Bar {}
+trait Foo {
+    type Res;
+    fn foo(&self) -> Self::Res;
+}
+impl Foo for i32 {
+    type Res = Self;
+    fn foo(&self) -> Self::Res { 1 }
+}
+fn main() {
+    let a: i32 = 1;
+    let c: Bar = todo!();
+}"#,
+            ],
         );
     }
 

crates/ide-diagnostics/src/lib.rs

@@ -92,7 +92,7 @@ use hir::{
 };
 use ide_db::{
     EditionedFileId, FileId, FileRange, FxHashMap, FxHashSet, RootDatabase, Severity, SnippetCap,
-    assists::{Assist, AssistId, AssistResolveStrategy},
+    assists::{Assist, AssistId, AssistResolveStrategy, ExprFillDefaultMode},
     base_db::{ReleaseChannel, RootQueryDb as _},
     generated::lints::{CLIPPY_LINT_GROUPS, DEFAULT_LINT_GROUPS, DEFAULT_LINTS, Lint, LintGroup},
     imports::insert_use::InsertUseConfig,
@@ -219,17 +219,6 @@ impl Diagnostic {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
-pub enum ExprFillDefaultMode {
-    Todo,
-    Default,
-}
-impl Default for ExprFillDefaultMode {
-    fn default() -> Self {
-        Self::Todo
-    }
-}
-
 #[derive(Debug, Clone)]
 pub struct DiagnosticsConfig {
     /// Whether native diagnostics are enabled.

crates/ide-diagnostics/src/tests.rs

@@ -3,14 +3,16 @@
 mod overly_long_real_world_cases;
 
 use ide_db::{
-    LineIndexDatabase, RootDatabase, assists::AssistResolveStrategy, base_db::SourceDatabase,
+    LineIndexDatabase, RootDatabase,
+    assists::{AssistResolveStrategy, ExprFillDefaultMode},
+    base_db::SourceDatabase,
 };
 use itertools::Itertools;
 use stdx::trim_indent;
 use test_fixture::WithFixture;
 use test_utils::{MiniCore, assert_eq_text, extract_annotations};
 
-use crate::{DiagnosticsConfig, ExprFillDefaultMode, Severity};
+use crate::{DiagnosticsConfig, Severity};
 
 /// Takes a multi-file input fixture with annotated cursor positions,
 /// and checks that:
@@ -160,55 +162,6 @@ pub(crate) fn check_has_fix(
     assert!(fix.is_some(), "no diagnostic with desired fix");
 }
 
-#[track_caller]
-pub(crate) fn check_has_single_fix(
-    #[rust_analyzer::rust_fixture] ra_fixture_before: &str,
-    #[rust_analyzer::rust_fixture] ra_fixture_after: &str,
-) {
-    let after = trim_indent(ra_fixture_after);
-
-    let (db, file_position) = RootDatabase::with_position(ra_fixture_before);
-    let mut conf = DiagnosticsConfig::test_sample();
-    conf.expr_fill_default = ExprFillDefaultMode::Default;
-    let mut n_fixes = 0;
-    let fix = super::full_diagnostics(
-        &db,
-        &conf,
-        &AssistResolveStrategy::All,
-        file_position.file_id.file_id(&db),
-    )
-    .into_iter()
-    .find(|d| {
-        d.fixes
-            .as_ref()
-            .and_then(|fixes| {
-                n_fixes += fixes.len();
-                fixes.iter().find(|fix| {
-                    if !fix.target.contains_inclusive(file_position.offset) {
-                        return false;
-                    }
-                    let actual = {
-                        let source_change = fix.source_change.as_ref().unwrap();
-                        let file_id = *source_change.source_file_edits.keys().next().unwrap();
-                        let mut actual = db.file_text(file_id).text(&db).to_string();
-
-                        for (edit, snippet_edit) in source_change.source_file_edits.values() {
-                            edit.apply(&mut actual);
-                            if let Some(snippet_edit) = snippet_edit {
-                                snippet_edit.apply(&mut actual);
-                            }
-                        }
-                        actual
-                    };
-                    after == actual
-                })
-            })
-            .is_some()
-    });
-    assert!(fix.is_some(), "no diagnostic with desired fix");
-    assert!(n_fixes == 1, "Too many fixes suggested");
-}
-
 /// Checks that there's a diagnostic *without* fix at `$0`.
 pub(crate) fn check_no_fix(#[rust_analyzer::rust_fixture] ra_fixture: &str) {
     let (db, file_position) = RootDatabase::with_position(ra_fixture);

crates/ide/src/doc_links.rs

@@ -599,7 +599,7 @@ fn filename_and_frag_for_def(
             Some(name) => {
                 match m.attrs(db).by_key(sym::doc).find_string_value_in_tt(sym::keyword) {
                     Some(kw) => {
-                        format!("keyword.{}.html", kw)
+                        format!("keyword.{kw}.html")
                     }
                     None => format!("{}/index.html", name.as_str()),
                 }

crates/ide/src/lib.rs

@@ -123,9 +123,9 @@ pub use ide_completion::{
     CallableSnippets, CompletionConfig, CompletionFieldsToResolve, CompletionItem,
     CompletionItemKind, CompletionItemRefMode, CompletionRelevance, Snippet, SnippetScope,
 };
-pub use ide_db::text_edit::{Indel, TextEdit};
 pub use ide_db::{
     FileId, FilePosition, FileRange, RootDatabase, Severity, SymbolKind,
+    assists::ExprFillDefaultMode,
     base_db::{Crate, CrateGraphBuilder, FileChange, SourceRoot, SourceRootId},
     documentation::Documentation,
     label::Label,
@@ -134,8 +134,9 @@ pub use ide_db::{
     search::{ReferenceCategory, SearchScope},
     source_change::{FileSystemEdit, SnippetEdit, SourceChange},
     symbol_index::Query,
+    text_edit::{Indel, TextEdit},
 };
-pub use ide_diagnostics::{Diagnostic, DiagnosticCode, DiagnosticsConfig, ExprFillDefaultMode};
+pub use ide_diagnostics::{Diagnostic, DiagnosticCode, DiagnosticsConfig};
 pub use ide_ssr::SsrError;
 pub use span::Edition;
 pub use syntax::{TextRange, TextSize};

crates/ide/src/moniker.rs

@@ -451,7 +451,7 @@ mod tests {
         assert_eq!(x.len(), 1);
         match x.into_iter().next().unwrap() {
             MonikerResult::Local { enclosing_moniker } => {
-                panic!("Unexpected local enclosed in {:?}", enclosing_moniker);
+                panic!("Unexpected local enclosed in {enclosing_moniker:?}");
             }
             MonikerResult::Moniker(x) => {
                 assert_eq!(identifier, x.identifier.to_string());

crates/ide/src/status.rs

@@ -51,8 +51,8 @@ pub(crate) fn status(db: &RootDatabase, file_id: Option<FileId>) -> String {
                 buf,
                 "Crate: {}\n",
                 match display_name {
-                    Some(it) => format!("{it}({:?})", crate_id),
-                    None => format!("{:?}", crate_id),
+                    Some(it) => format!("{it}({crate_id:?})"),
+                    None => format!("{crate_id:?}"),
                 }
             );
             format_to!(buf, "    Root module file id: {}\n", root_file_id.index());

crates/ide/src/view_crate_graph.rs

@@ -80,7 +80,7 @@ impl<'a> dot::Labeller<'a, Crate, Edge<'a>> for DotCrateGraph<'_> {
 
     fn node_id(&'a self, n: &Crate) -> Id<'a> {
         let id = n.as_id().as_u32();
-        Id::new(format!("_{:?}", id)).unwrap()
+        Id::new(format!("_{id:?}")).unwrap()
     }
 
     fn node_shape(&'a self, _node: &Crate) -> Option<LabelText<'a>> {

crates/proc-macro-srv/build.rs

@@ -12,5 +12,5 @@ fn main() {
     let version_string = std::str::from_utf8(&output.stdout[..])
         .expect("rustc --version output must be UTF-8")
         .trim();
-    println!("cargo::rustc-env=RUSTC_VERSION={}", version_string);
+    println!("cargo::rustc-env=RUSTC_VERSION={version_string}");
 }

crates/query-group-macro/tests/logger_db.rs

@@ -40,7 +40,7 @@ impl LoggerDb {
     /// it is meant to be run from outside any tracked functions.
     pub(crate) fn assert_logs(&self, expected: expect_test::Expect) {
         let logs = std::mem::take(&mut *self.logger.logs.lock().unwrap());
-        expected.assert_eq(&format!("{:#?}", logs));
+        expected.assert_eq(&format!("{logs:#?}"));
     }
 }
 

crates/rust-analyzer/src/cli/analysis_stats.rs

@@ -175,7 +175,7 @@ impl flags::AnalysisStats {
             UsizeWithUnderscore(dep_loc),
             UsizeWithUnderscore(dep_item_trees),
         );
-        eprintln!("  dependency item stats: {}", dep_item_stats);
+        eprintln!("  dependency item stats: {dep_item_stats}");
 
         // FIXME(salsa-transition): bring back stats for ParseQuery (file size)
         // and ParseMacroExpansionQuery (macro expansion "file") size whenever we implement
@@ -295,7 +295,7 @@ impl flags::AnalysisStats {
             UsizeWithUnderscore(workspace_loc),
             UsizeWithUnderscore(workspace_item_trees),
         );
-        eprintln!("    usages: {}", workspace_item_stats);
+        eprintln!("    usages: {workspace_item_stats}");
 
         eprintln!("  Dependencies:");
         eprintln!(
@@ -303,7 +303,7 @@ impl flags::AnalysisStats {
             UsizeWithUnderscore(dep_loc),
             UsizeWithUnderscore(dep_item_trees),
         );
-        eprintln!("    declarations: {}", dep_item_stats);
+        eprintln!("    declarations: {dep_item_stats}");
 
         let crate_def_map_time = crate_def_map_sw.elapsed();
         eprintln!("{:<20} {}", "Item Collection:", crate_def_map_time);
@@ -1294,7 +1294,7 @@ impl fmt::Display for UsizeWithUnderscore {
         let num_str = self.0.to_string();
 
         if num_str.len() <= 3 {
-            return write!(f, "{}", num_str);
+            return write!(f, "{num_str}");
         }
 
         let mut result = String::new();
@@ -1307,7 +1307,7 @@ impl fmt::Display for UsizeWithUnderscore {
         }
 
         let result = result.chars().rev().collect::<String>();
-        write!(f, "{}", result)
+        write!(f, "{result}")
     }
 }
 

crates/rust-analyzer/src/cli/scip.rs

@@ -265,10 +265,10 @@ impl flags::Scip {
         };
 
         if !duplicate_symbol_errors.is_empty() {
-            eprintln!("{}", DUPLICATE_SYMBOLS_MESSAGE);
+            eprintln!("{DUPLICATE_SYMBOLS_MESSAGE}");
             for (source_location, symbol) in duplicate_symbol_errors {
-                eprintln!("{}", source_location);
-                eprintln!("  Duplicate symbol: {}", symbol);
+                eprintln!("{source_location}");
+                eprintln!("  Duplicate symbol: {symbol}");
                 eprintln!();
             }
         }

crates/rust-analyzer/src/config.rs

@@ -9,13 +9,14 @@ use cfg::{CfgAtom, CfgDiff};
 use hir::Symbol;
 use ide::{
     AssistConfig, CallHierarchyConfig, CallableSnippets, CompletionConfig,
-    CompletionFieldsToResolve, DiagnosticsConfig, ExprFillDefaultMode, GenericParameterHints,
-    HighlightConfig, HighlightRelatedConfig, HoverConfig, HoverDocFormat, InlayFieldsToResolve,
-    InlayHintsConfig, JoinLinesConfig, MemoryLayoutHoverConfig, MemoryLayoutHoverRenderKind,
-    Snippet, SnippetScope, SourceRootId,
+    CompletionFieldsToResolve, DiagnosticsConfig, GenericParameterHints, HighlightConfig,
+    HighlightRelatedConfig, HoverConfig, HoverDocFormat, InlayFieldsToResolve, InlayHintsConfig,
+    JoinLinesConfig, MemoryLayoutHoverConfig, MemoryLayoutHoverRenderKind, Snippet, SnippetScope,
+    SourceRootId,
 };
 use ide_db::{
     SnippetCap,
+    assists::ExprFillDefaultMode,
     imports::insert_use::{ImportGranularity, InsertUseConfig, PrefixKind},
 };
 use itertools::{Either, Itertools};
@@ -1493,6 +1494,11 @@ impl Config {
             term_search_fuel: self.assist_termSearch_fuel(source_root).to_owned() as u64,
             term_search_borrowck: self.assist_termSearch_borrowcheck(source_root).to_owned(),
             code_action_grouping: self.code_action_group(),
+            expr_fill_default: match self.assist_expressionFillDefault(source_root) {
+                ExprFillDefaultDef::Todo => ExprFillDefaultMode::Todo,
+                ExprFillDefaultDef::Default => ExprFillDefaultMode::Default,
+                ExprFillDefaultDef::Underscore => ExprFillDefaultMode::Underscore,
+            },
         }
     }
 
@@ -1577,6 +1583,7 @@ impl Config {
             expr_fill_default: match self.assist_expressionFillDefault(source_root) {
                 ExprFillDefaultDef::Todo => ExprFillDefaultMode::Todo,
                 ExprFillDefaultDef::Default => ExprFillDefaultMode::Default,
+                ExprFillDefaultDef::Underscore => ExprFillDefaultMode::Underscore,
             },
             snippet_cap: self.snippet_cap(),
             insert_use: self.insert_use_config(source_root),
@@ -2527,6 +2534,7 @@ where
 enum ExprFillDefaultDef {
     Todo,
     Default,
+    Underscore,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone)]

crates/syntax/src/ast/make.rs

@@ -69,6 +69,9 @@ pub mod ext {
     pub fn expr_todo() -> ast::Expr {
         expr_from_text("todo!()")
     }
+    pub fn expr_underscore() -> ast::Expr {
+        expr_from_text("_")
+    }
     pub fn expr_ty_default(ty: &ast::Type) -> ast::Expr {
         expr_from_text(&format!("{ty}::default()"))
     }

crates/tt/src/lib.rs

@@ -728,9 +728,9 @@ fn print_debug_subtree<S: fmt::Debug>(
     };
 
     write!(f, "{align}SUBTREE {delim} ",)?;
-    write!(f, "{:#?}", open)?;
+    write!(f, "{open:#?}")?;
     write!(f, " ")?;
-    write!(f, "{:#?}", close)?;
+    write!(f, "{close:#?}")?;
     for child in iter {
         writeln!(f)?;
         print_debug_token(f, level + 1, child)?;
@@ -855,7 +855,7 @@ impl<S> fmt::Display for Literal<S> {
             }
         }?;
         if let Some(suffix) = &self.suffix {
-            write!(f, "{}", suffix)?;
+            write!(f, "{suffix}")?;
         }
         Ok(())
     }

xtask/src/codegen/grammar.rs

@@ -414,7 +414,7 @@ fn generate_nodes(kinds: KindsSrc, grammar: &AstSrc) -> String {
         .map(|kind| to_pascal_case(kind))
         .filter(|name| !defined_nodes.iter().any(|&it| it == name))
     {
-        eprintln!("Warning: node {} not defined in AST source", node);
+        eprintln!("Warning: node {node} not defined in AST source");
         drop(node);
     }
 

xtask/src/codegen/parser_inline_tests.rs

@@ -159,7 +159,7 @@ fn collect_tests(s: &str) -> Vec<Test> {
                 (name.to_owned(), Some(edition.to_owned()))
             }
             [name] => (name.to_owned(), None),
-            _ => panic!("invalid test name: {:?}", name),
+            _ => panic!("invalid test name: {name:?}"),
         };
         let text: String = edition
             .as_ref()
@@ -212,7 +212,7 @@ fn existing_tests(dir: &Path, ok: TestKind) -> Result<HashMap<String, (PathBuf,
                 text.lines().next().and_then(|it| it.strip_prefix("// ")).map(ToOwned::to_owned);
             let test = Test { name: name.clone(), text, kind: ok, edition };
             if let Some(old) = res.insert(name, (path, test)) {
-                println!("Duplicate test: {:?}", old);
+                println!("Duplicate test: {old:?}");
             }
         }
     }