5 files changed, 361 insertions, 30 deletions

diff --git a/crates/ide_assists/src/handlers/fill_match_arms.rs b/crates/ide_assists/src/handlers/fill_match_arms.rs
index 80bd1b7e8..a30c4d04e 100644
--- a/crates/ide_assists/src/handlers/fill_match_arms.rs
+++ b/crates/ide_assists/src/handlers/fill_match_arms.rs
@@ -1,5 +1,6 @@
 use std::iter;
 
+use either::Either;
 use hir::{Adt, HasSource, ModuleDef, Semantics};
 use ide_db::helpers::{mod_path_to_ast, FamousDefs};
 use ide_db::RootDatabase;
@@ -7,7 +8,7 @@ use itertools::Itertools;
 use syntax::ast::{self, make, AstNode, MatchArm, NameOwner, Pat};
 
 use crate::{
-    utils::{does_pat_match_variant, render_snippet, Cursor},
+    utils::{self, render_snippet, Cursor},
     AssistContext, AssistId, AssistKind, Assists,
 };
 
@@ -48,6 +49,18 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
         }
     }
 
+    let top_lvl_pats: Vec<_> = arms
+        .iter()
+        .filter_map(ast::MatchArm::pat)
+        .flat_map(|pat| match pat {
+            // Special casee OrPat as separate top-level pats
+            Pat::OrPat(or_pat) => Either::Left(or_pat.pats()),
+            _ => Either::Right(iter::once(pat)),
+        })
+        // Exclude top level wildcards so that they are expanded by this assist, retains status quo in #8129.
+        .filter(|pat| !matches!(pat, Pat::WildcardPat(_)))
+        .collect();
+
     let module = ctx.sema.scope(expr.syntax()).module()?;
 
     let missing_arms: Vec<MatchArm> = if let Some(enum_def) = resolve_enum_def(&ctx.sema, &expr) {
@@ -56,7 +69,7 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
         let mut variants = variants
             .into_iter()
             .filter_map(|variant| build_pat(ctx.db(), module, variant))
-            .filter(|variant_pat| is_variant_missing(&mut arms, variant_pat))
+            .filter(|variant_pat| is_variant_missing(&top_lvl_pats, variant_pat))
             .map(|pat| make::match_arm(iter::once(pat), make::expr_empty_block()))
             .collect::<Vec<_>>();
         if Some(enum_def) == FamousDefs(&ctx.sema, Some(module.krate())).core_option_Option() {
@@ -66,11 +79,6 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
         }
         variants
     } else if let Some(enum_defs) = resolve_tuple_of_enum_def(&ctx.sema, &expr) {
-        // Partial fill not currently supported for tuple of enums.
-        if !arms.is_empty() {
-            return None;
-        }
-
         // When calculating the match arms for a tuple of enums, we want
         // to create a match arm for each possible combination of enum
         // values. The `multi_cartesian_product` method transforms
@@ -85,7 +93,7 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
                     variants.into_iter().filter_map(|variant| build_pat(ctx.db(), module, variant));
                 ast::Pat::from(make::tuple_pat(patterns))
             })
-            .filter(|variant_pat| is_variant_missing(&mut arms, variant_pat))
+            .filter(|variant_pat| is_variant_missing(&top_lvl_pats, variant_pat))
             .map(|pat| make::match_arm(iter::once(pat), make::expr_empty_block()))
             .collect()
     } else {
@@ -128,16 +136,19 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
     )
 }
 
-fn is_variant_missing(existing_arms: &mut Vec<MatchArm>, var: &Pat) -> bool {
-    existing_arms.iter().filter_map(|arm| arm.pat()).all(|pat| {
-        // Special casee OrPat as separate top-level pats
-        let top_level_pats: Vec<Pat> = match pat {
-            Pat::OrPat(pats) => pats.pats().collect::<Vec<_>>(),
-            _ => vec![pat],
-        };
+fn is_variant_missing(existing_pats: &[Pat], var: &Pat) -> bool {
+    !existing_pats.iter().any(|pat| does_pat_match_variant(pat, var))
+}
 
-        !top_level_pats.iter().any(|pat| does_pat_match_variant(pat, var))
-    })
+// Fixme: this is still somewhat limited, use hir_ty::diagnostics::match_check?
+fn does_pat_match_variant(pat: &Pat, var: &Pat) -> bool {
+    match (pat, var) {
+        (Pat::WildcardPat(_), _) => true,
+        (Pat::TuplePat(tpat), Pat::TuplePat(tvar)) => {
+            tpat.fields().zip(tvar.fields()).all(|(p, v)| does_pat_match_variant(&p, &v))
+        }
+        _ => utils::does_pat_match_variant(pat, var),
+    }
 }
 
 fn resolve_enum_def(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> Option<hir::Enum> {
@@ -467,20 +478,81 @@ fn main() {
 
     #[test]
     fn fill_match_arms_tuple_of_enum_partial() {
-        check_assist_not_applicable(
+        check_assist(
             fill_match_arms,
             r#"
-            enum A { One, Two }
-            enum B { One, Two }
+enum A { One, Two }
+enum B { One, Two }
 
-            fn main() {
-                let a = A::One;
-                let b = B::One;
-                match (a$0, b) {
-                    (A::Two, B::One) => {}
-                }
-            }
-            "#,
+fn main() {
+    let a = A::One;
+    let b = B::One;
+    match (a$0, b) {
+        (A::Two, B::One) => {}
+    }
+}
+"#,
+            r#"
+enum A { One, Two }
+enum B { One, Two }
+
+fn main() {
+    let a = A::One;
+    let b = B::One;
+    match (a, b) {
+        (A::Two, B::One) => {}
+        $0(A::One, B::One) => {}
+        (A::One, B::Two) => {}
+        (A::Two, B::Two) => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn fill_match_arms_tuple_of_enum_partial_with_wildcards() {
+        let ra_fixture = r#"
+fn main() {
+    let a = Some(1);
+    let b = Some(());
+    match (a$0, b) {
+        (Some(_), _) => {}
+        (None, Some(_)) => {}
+    }
+}
+"#;
+        check_assist(
+            fill_match_arms,
+            &format!("//- /main.rs crate:main deps:core{}{}", ra_fixture, FamousDefs::FIXTURE),
+            r#"
+fn main() {
+    let a = Some(1);
+    let b = Some(());
+    match (a, b) {
+        (Some(_), _) => {}
+        (None, Some(_)) => {}
+        $0(None, None) => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn fill_match_arms_partial_with_deep_pattern() {
+        // Fixme: cannot handle deep patterns
+        let ra_fixture = r#"
+fn main() {
+    match $0Some(true) {
+        Some(true) => {}
+        None => {}
+    }
+}
+"#;
+        check_assist_not_applicable(
+            fill_match_arms,
+            &format!("//- /main.rs crate:main deps:core{}{}", ra_fixture, FamousDefs::FIXTURE),
         );
     }
 
diff --git a/crates/ide_assists/src/handlers/generate_deref.rs b/crates/ide_assists/src/handlers/generate_deref.rs
new file mode 100644
index 000000000..4998ff7a4
--- /dev/null
+++ b/crates/ide_assists/src/handlers/generate_deref.rs
@@ -0,0 +1,227 @@
+use std::fmt::Display;
+
+use ide_db::{helpers::FamousDefs, RootDatabase};
+use syntax::{
+    ast::{self, NameOwner},
+    AstNode, SyntaxNode,
+};
+
+use crate::{
+    assist_context::{AssistBuilder, AssistContext, Assists},
+    utils::generate_trait_impl_text,
+    AssistId, AssistKind,
+};
+
+// Assist: generate_deref
+//
+// Generate `Deref` impl using the given struct field.
+//
+// ```
+// struct A;
+// struct B {
+//    $0a: A
+// }
+// ```
+// ->
+// ```
+// struct A;
+// struct B {
+//    a: A
+// }
+//
+// impl std::ops::Deref for B {
+//     type Target = A;
+//
+//     fn deref(&self) -> &Self::Target {
+//         &self.a
+//     }
+// }
+// ```
+pub(crate) fn generate_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    generate_record_deref(acc, ctx).or_else(|| generate_tuple_deref(acc, ctx))
+}
+
+fn generate_record_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
+    let field = ctx.find_node_at_offset::<ast::RecordField>()?;
+
+    if existing_deref_impl(&ctx.sema, &strukt).is_some() {
+        cov_mark::hit!(test_add_record_deref_impl_already_exists);
+        return None;
+    }
+
+    let field_type = field.ty()?;
+    let field_name = field.name()?;
+    let target = field.syntax().text_range();
+    acc.add(
+        AssistId("generate_deref", AssistKind::Generate),
+        format!("Generate `Deref` impl using `{}`", field_name),
+        target,
+        |edit| generate_edit(edit, strukt, field_type.syntax(), field_name.syntax()),
+    )
+}
+
+fn generate_tuple_deref(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
+    let field = ctx.find_node_at_offset::<ast::TupleField>()?;
+    let field_list = ctx.find_node_at_offset::<ast::TupleFieldList>()?;
+    let field_list_index =
+        field_list.syntax().children().into_iter().position(|s| &s == field.syntax())?;
+
+    if existing_deref_impl(&ctx.sema, &strukt).is_some() {
+        cov_mark::hit!(test_add_field_deref_impl_already_exists);
+        return None;
+    }
+
+    let field_type = field.ty()?;
+    let target = field.syntax().text_range();
+    acc.add(
+        AssistId("generate_deref", AssistKind::Generate),
+        format!("Generate `Deref` impl using `{}`", field.syntax()),
+        target,
+        |edit| generate_edit(edit, strukt, field_type.syntax(), field_list_index),
+    )
+}
+
+fn generate_edit(
+    edit: &mut AssistBuilder,
+    strukt: ast::Struct,
+    field_type_syntax: &SyntaxNode,
+    field_name: impl Display,
+) {
+    let start_offset = strukt.syntax().text_range().end();
+    let impl_code = format!(
+        r#"    type Target = {0};
+
+    fn deref(&self) -> &Self::Target {{
+        &self.{1}
+    }}"#,
+        field_type_syntax, field_name
+    );
+    let strukt_adt = ast::Adt::Struct(strukt);
+    let deref_impl = generate_trait_impl_text(&strukt_adt, "std::ops::Deref", &impl_code);
+    edit.insert(start_offset, deref_impl);
+}
+
+fn existing_deref_impl(
+    sema: &'_ hir::Semantics<'_, RootDatabase>,
+    strukt: &ast::Struct,
+) -> Option<()> {
+    let strukt = sema.to_def(strukt)?;
+    let krate = strukt.module(sema.db).krate();
+
+    let deref_trait = FamousDefs(sema, Some(krate)).core_ops_Deref()?;
+    let strukt_type = strukt.ty(sema.db);
+
+    if strukt_type.impls_trait(sema.db, deref_trait, &[]) {
+        Some(())
+    } else {
+        None
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable};
+
+    use super::*;
+
+    #[test]
+    fn test_generate_record_deref() {
+        check_assist(
+            generate_deref,
+            r#"struct A { }
+struct B { $0a: A }"#,
+            r#"struct A { }
+struct B { a: A }
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.a
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn test_generate_field_deref_idx_0() {
+        check_assist(
+            generate_deref,
+            r#"struct A { }
+struct B($0A);"#,
+            r#"struct A { }
+struct B(A);
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}"#,
+        );
+    }
+    #[test]
+    fn test_generate_field_deref_idx_1() {
+        check_assist(
+            generate_deref,
+            r#"struct A { }
+struct B(u8, $0A);"#,
+            r#"struct A { }
+struct B(u8, A);
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.1
+    }
+}"#,
+        );
+    }
+
+    fn check_not_applicable(ra_fixture: &str) {
+        let fixture = format!(
+            "//- /main.rs crate:main deps:core,std\n{}\n{}",
+            ra_fixture,
+            FamousDefs::FIXTURE
+        );
+        check_assist_not_applicable(generate_deref, &fixture)
+    }
+
+    #[test]
+    fn test_generate_record_deref_not_applicable_if_already_impl() {
+        cov_mark::check!(test_add_record_deref_impl_already_exists);
+        check_not_applicable(
+            r#"struct A { }
+struct B { $0a: A }
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.a
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn test_generate_field_deref_not_applicable_if_already_impl() {
+        cov_mark::check!(test_add_field_deref_impl_already_exists);
+        check_not_applicable(
+            r#"struct A { }
+struct B($0A)
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}"#,
+        )
+    }
+}
diff --git a/crates/ide_assists/src/lib.rs b/crates/ide_assists/src/lib.rs
index 3694f468f..8996c1b61 100644
--- a/crates/ide_assists/src/lib.rs
+++ b/crates/ide_assists/src/lib.rs
@@ -134,6 +134,7 @@ mod handlers {
     mod generate_default_from_enum_variant;
     mod generate_default_from_new;
     mod generate_is_empty_from_len;
+    mod generate_deref;
     mod generate_derive;
     mod generate_enum_is_method;
     mod generate_enum_projection_method;
@@ -201,6 +202,7 @@ mod handlers {
             generate_default_from_enum_variant::generate_default_from_enum_variant,
             generate_default_from_new::generate_default_from_new,
             generate_is_empty_from_len::generate_is_empty_from_len,
+            generate_deref::generate_deref,
             generate_derive::generate_derive,
             generate_enum_is_method::generate_enum_is_method,
             generate_enum_projection_method::generate_enum_as_method,
diff --git a/crates/ide_assists/src/tests.rs b/crates/ide_assists/src/tests.rs
index a7a923beb..49533e7d2 100644
--- a/crates/ide_assists/src/tests.rs
+++ b/crates/ide_assists/src/tests.rs
@@ -84,7 +84,8 @@ fn check_doc_test(assist_id: &str, before: &str, after: &str) {
         });
 
     let actual = {
-        let source_change = assist.source_change.unwrap();
+        let source_change =
+            assist.source_change.expect("Assist did not contain any source changes");
         let mut actual = before;
         if let Some(source_file_edit) = source_change.get_source_edit(file_id) {
             source_file_edit.apply(&mut actual);
@@ -121,7 +122,8 @@ fn check(handler: Handler, before: &str, expected: ExpectedResult, assist_label:
 
     match (assist, expected) {
         (Some(assist), ExpectedResult::After(after)) => {
-            let source_change = assist.source_change.unwrap();
+            let source_change =
+                assist.source_change.expect("Assist did not contain any source changes");
             assert!(!source_change.source_file_edits.is_empty());
             let skip_header = source_change.source_file_edits.len() == 1
                 && source_change.file_system_edits.len() == 0;
@@ -191,6 +193,7 @@ fn assist_order_field_struct() {
     let mut assists = assists.iter();
 
     assert_eq!(assists.next().expect("expected assist").label, "Change visibility to pub(crate)");
+    assert_eq!(assists.next().expect("expected assist").label, "Generate `Deref` impl using `bar`");
     assert_eq!(assists.next().expect("expected assist").label, "Generate a mut getter method");
     assert_eq!(assists.next().expect("expected assist").label, "Generate a getter method");
     assert_eq!(assists.next().expect("expected assist").label, "Generate a setter method");
diff --git a/crates/ide_assists/src/tests/generated.rs b/crates/ide_assists/src/tests/generated.rs
index 27a22ca10..41559b43a 100644
--- a/crates/ide_assists/src/tests/generated.rs
+++ b/crates/ide_assists/src/tests/generated.rs
@@ -552,6 +552,33 @@ impl Default for Example {
 }
 
 #[test]
+fn doctest_generate_deref() {
+    check_doc_test(
+        "generate_deref",
+        r#####"
+struct A;
+struct B {
+   $0a: A
+}
+"#####,
+        r#####"
+struct A;
+struct B {
+   a: A
+}
+
+impl std::ops::Deref for B {
+    type Target = A;
+
+    fn deref(&self) -> &Self::Target {
+        &self.a
+    }
+}
+"#####,
+    )
+}
+
+#[test]
 fn doctest_generate_derive() {
     check_doc_test(
         "generate_derive",