Add expression fill mode variant for filling with underscore expressions

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);