6 files changed, 591 insertions, 7 deletions

diff --git a/crates/ra_assists/src/ast_transform.rs b/crates/ra_assists/src/ast_transform.rs
index 9ac65ab39..3079a02a2 100644
--- a/crates/ra_assists/src/ast_transform.rs
+++ b/crates/ra_assists/src/ast_transform.rs
@@ -1,7 +1,7 @@
 //! `AstTransformer`s are functions that replace nodes in an AST and can be easily combined.
 use rustc_hash::FxHashMap;
 
-use hir::{PathResolution, SemanticsScope};
+use hir::{HirDisplay, PathResolution, SemanticsScope};
 use ra_ide_db::RootDatabase;
 use ra_syntax::{
     algo::SyntaxRewriter,
@@ -51,7 +51,27 @@ impl<'a> SubstituteTypeParams<'a> {
             .into_iter()
             // this is a trait impl, so we need to skip the first type parameter -- this is a bit hacky
             .skip(1)
-            .zip(substs.into_iter())
+            // The actual list of trait type parameters may be longer than the one
+            // used in the `impl` block due to trailing default type parametrs.
+            // For that case we extend the `substs` with an empty iterator so we
+            // can still hit those trailing values and check if they actually have
+            // a default type. If they do, go for that type from `hir` to `ast` so
+            // the resulting change can be applied correctly.
+            .zip(substs.into_iter().map(Some).chain(std::iter::repeat(None)))
+            .filter_map(|(k, v)| match v {
+                Some(v) => Some((k, v)),
+                None => {
+                    let default = k.default(source_scope.db)?;
+                    Some((
+                        k,
+                        ast::make::type_ref(
+                            &default
+                                .display_source_code(source_scope.db, source_scope.module()?.into())
+                                .ok()?,
+                        ),
+                    ))
+                }
+            })
             .collect();
         return SubstituteTypeParams {
             source_scope,
diff --git a/crates/ra_assists/src/handlers/add_custom_impl.rs b/crates/ra_assists/src/handlers/add_custom_impl.rs
index 795a225a4..2baeb8607 100644
--- a/crates/ra_assists/src/handlers/add_custom_impl.rs
+++ b/crates/ra_assists/src/handlers/add_custom_impl.rs
@@ -49,7 +49,7 @@ pub(crate) fn add_custom_impl(acc: &mut Assists, ctx: &AssistContext) -> Option<
     let start_offset = annotated.syntax().parent()?.text_range().end();
 
     let label =
-        format!("Add custom impl '{}' for '{}'", trait_token.text().as_str(), annotated_name);
+        format!("Add custom impl `{}` for `{}`", trait_token.text().as_str(), annotated_name);
 
     let target = attr.syntax().text_range();
     acc.add(AssistId("add_custom_impl"), label, target, |edit| {
diff --git a/crates/ra_assists/src/handlers/add_explicit_type.rs b/crates/ra_assists/src/handlers/add_explicit_type.rs
index 7ced00626..0c7d5e355 100644
--- a/crates/ra_assists/src/handlers/add_explicit_type.rs
+++ b/crates/ra_assists/src/handlers/add_explicit_type.rs
@@ -61,7 +61,7 @@ pub(crate) fn add_explicit_type(acc: &mut Assists, ctx: &AssistContext) -> Optio
     let inferred_type = ty.display_source_code(ctx.db, module.into()).ok()?;
     acc.add(
         AssistId("add_explicit_type"),
-        format!("Insert explicit type '{}'", inferred_type),
+        format!("Insert explicit type `{}`", inferred_type),
         pat_range,
         |builder| match ascribed_ty {
             Some(ascribed_ty) => {
diff --git a/crates/ra_assists/src/handlers/add_missing_impl_members.rs b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
index c1ce87914..22e1156d2 100644
--- a/crates/ra_assists/src/handlers/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/handlers/add_missing_impl_members.rs
@@ -618,4 +618,54 @@ impl Foo for S {
 }"#,
         )
     }
+
+    #[test]
+    fn test_generic_single_default_parameter() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+trait Foo<T = Self> {
+    fn bar(&self, other: &T);
+}
+
+struct S;
+impl Foo for S { <|> }"#,
+            r#"
+trait Foo<T = Self> {
+    fn bar(&self, other: &T);
+}
+
+struct S;
+impl Foo for S {
+    <|>fn bar(&self, other: &Self) {
+        todo!()
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn test_generic_default_parameter_is_second() {
+        check_assist(
+            add_missing_impl_members,
+            r#"
+trait Foo<T1, T2 = Self> {
+    fn bar(&self, this: &T1, that: &T2);
+}
+
+struct S<T>;
+impl Foo<T> for S<T> { <|> }"#,
+            r#"
+trait Foo<T1, T2 = Self> {
+    fn bar(&self, this: &T1, that: &T2);
+}
+
+struct S<T>;
+impl Foo<T> for S<T> {
+    <|>fn bar(&self, this: &T, that: &Self) {
+        todo!()
+    }
+}"#,
+        )
+    }
 }
diff --git a/crates/ra_assists/src/handlers/change_visibility.rs b/crates/ra_assists/src/handlers/change_visibility.rs
index e631766ef..40cf4b422 100644
--- a/crates/ra_assists/src/handlers/change_visibility.rs
+++ b/crates/ra_assists/src/handlers/change_visibility.rs
@@ -5,11 +5,14 @@ use ra_syntax::{
         ATTR, COMMENT, CONST_DEF, ENUM_DEF, FN_DEF, MODULE, STRUCT_DEF, TRAIT_DEF, VISIBILITY,
         WHITESPACE,
     },
-    SyntaxNode, TextSize, T,
+    SyntaxNode, TextRange, TextSize, T,
 };
+
+use hir::{db::HirDatabase, HasSource, HasVisibility, PathResolution};
 use test_utils::tested_by;
 
 use crate::{AssistContext, AssistId, Assists};
+use ra_db::FileId;
 
 // Assist: change_visibility
 //
@@ -27,6 +30,8 @@ pub(crate) fn change_visibility(acc: &mut Assists, ctx: &AssistContext) -> Optio
         return change_vis(acc, vis);
     }
     add_vis(acc, ctx)
+        .or_else(|| add_vis_to_referenced_module_def(acc, ctx))
+        .or_else(|| add_vis_to_referenced_record_field(acc, ctx))
 }
 
 fn add_vis(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
@@ -72,6 +77,143 @@ fn add_vis(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     })
 }
 
+fn add_vis_to_referenced_module_def(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let path: ast::Path = ctx.find_node_at_offset()?;
+    let path_res = ctx.sema.resolve_path(&path)?;
+    let def = match path_res {
+        PathResolution::Def(def) => def,
+        _ => return None,
+    };
+
+    let current_module = ctx.sema.scope(&path.syntax()).module()?;
+    let target_module = def.module(ctx.db)?;
+
+    let vis = target_module.visibility_of(ctx.db, &def)?;
+    if vis.is_visible_from(ctx.db, current_module.into()) {
+        return None;
+    };
+
+    let (offset, target, target_file, target_name) = target_data_for_def(ctx.db, def)?;
+
+    let missing_visibility =
+        if current_module.krate() == target_module.krate() { "pub(crate)" } else { "pub" };
+
+    let assist_label = match target_name {
+        None => format!("Change visibility to {}", missing_visibility),
+        Some(name) => format!("Change visibility of {} to {}", name, missing_visibility),
+    };
+
+    acc.add(AssistId("change_visibility"), assist_label, target, |edit| {
+        edit.set_file(target_file);
+        edit.insert(offset, format!("{} ", missing_visibility));
+        edit.set_cursor(offset);
+    })
+}
+
+fn add_vis_to_referenced_record_field(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let record_field: ast::RecordField = ctx.find_node_at_offset()?;
+    let (record_field_def, _) = ctx.sema.resolve_record_field(&record_field)?;
+
+    let current_module = ctx.sema.scope(record_field.syntax()).module()?;
+    let visibility = record_field_def.visibility(ctx.db);
+    if visibility.is_visible_from(ctx.db, current_module.into()) {
+        return None;
+    }
+
+    let parent = record_field_def.parent_def(ctx.db);
+    let parent_name = parent.name(ctx.db);
+    let target_module = parent.module(ctx.db);
+
+    let in_file_source = record_field_def.source(ctx.db);
+    let (offset, target) = match in_file_source.value {
+        hir::FieldSource::Named(it) => {
+            let s = it.syntax();
+            (vis_offset(s), s.text_range())
+        }
+        hir::FieldSource::Pos(it) => {
+            let s = it.syntax();
+            (vis_offset(s), s.text_range())
+        }
+    };
+
+    let missing_visibility =
+        if current_module.krate() == target_module.krate() { "pub(crate)" } else { "pub" };
+    let target_file = in_file_source.file_id.original_file(ctx.db);
+
+    let target_name = record_field_def.name(ctx.db);
+    let assist_label =
+        format!("Change visibility of {}.{} to {}", parent_name, target_name, missing_visibility);
+
+    acc.add(AssistId("change_visibility"), assist_label, target, |edit| {
+        edit.set_file(target_file);
+        edit.insert(offset, format!("{} ", missing_visibility));
+        edit.set_cursor(offset)
+    })
+}
+
+fn target_data_for_def(
+    db: &dyn HirDatabase,
+    def: hir::ModuleDef,
+) -> Option<(TextSize, TextRange, FileId, Option<hir::Name>)> {
+    fn offset_target_and_file_id<S, Ast>(
+        db: &dyn HirDatabase,
+        x: S,
+    ) -> (TextSize, TextRange, FileId)
+    where
+        S: HasSource<Ast = Ast>,
+        Ast: AstNode,
+    {
+        let source = x.source(db);
+        let in_file_syntax = source.syntax();
+        let file_id = in_file_syntax.file_id;
+        let syntax = in_file_syntax.value;
+        (vis_offset(syntax), syntax.text_range(), file_id.original_file(db.upcast()))
+    }
+
+    let target_name;
+    let (offset, target, target_file) = match def {
+        hir::ModuleDef::Function(f) => {
+            target_name = Some(f.name(db));
+            offset_target_and_file_id(db, f)
+        }
+        hir::ModuleDef::Adt(adt) => {
+            target_name = Some(adt.name(db));
+            match adt {
+                hir::Adt::Struct(s) => offset_target_and_file_id(db, s),
+                hir::Adt::Union(u) => offset_target_and_file_id(db, u),
+                hir::Adt::Enum(e) => offset_target_and_file_id(db, e),
+            }
+        }
+        hir::ModuleDef::Const(c) => {
+            target_name = c.name(db);
+            offset_target_and_file_id(db, c)
+        }
+        hir::ModuleDef::Static(s) => {
+            target_name = s.name(db);
+            offset_target_and_file_id(db, s)
+        }
+        hir::ModuleDef::Trait(t) => {
+            target_name = Some(t.name(db));
+            offset_target_and_file_id(db, t)
+        }
+        hir::ModuleDef::TypeAlias(t) => {
+            target_name = Some(t.name(db));
+            offset_target_and_file_id(db, t)
+        }
+        hir::ModuleDef::Module(m) => {
+            target_name = m.name(db);
+            let in_file_source = m.declaration_source(db)?;
+            let file_id = in_file_source.file_id.original_file(db.upcast());
+            let syntax = in_file_source.value.syntax();
+            (vis_offset(syntax), syntax.text_range(), file_id)
+        }
+        // Enum variants can't be private, we can't modify builtin types
+        hir::ModuleDef::EnumVariant(_) | hir::ModuleDef::BuiltinType(_) => return None,
+    };
+
+    Some((offset, target, target_file, target_name))
+}
+
 fn vis_offset(node: &SyntaxNode) -> TextSize {
     node.children_with_tokens()
         .skip_while(|it| match it.kind() {
@@ -192,6 +334,378 @@ mod tests {
     }
 
     #[test]
+    fn change_visibility_of_fn_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { fn foo() {} }
+              fn main() { foo::foo<|>() } ",
+            r"mod foo { <|>pub(crate) fn foo() {} }
+              fn main() { foo::foo() } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub fn foo() {} }
+              fn main() { foo::foo<|>() } ",
+        )
+    }
+
+    #[test]
+    fn change_visibility_of_adt_in_submodule_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { struct Foo; }
+              fn main() { foo::Foo<|> } ",
+            r"mod foo { <|>pub(crate) struct Foo; }
+              fn main() { foo::Foo } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub struct Foo; }
+              fn main() { foo::Foo<|> } ",
+        );
+        check_assist(
+            change_visibility,
+            r"mod foo { enum Foo; }
+              fn main() { foo::Foo<|> } ",
+            r"mod foo { <|>pub(crate) enum Foo; }
+              fn main() { foo::Foo } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub enum Foo; }
+              fn main() { foo::Foo<|> } ",
+        );
+        check_assist(
+            change_visibility,
+            r"mod foo { union Foo; }
+              fn main() { foo::Foo<|> } ",
+            r"mod foo { <|>pub(crate) union Foo; }
+              fn main() { foo::Foo } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub union Foo; }
+              fn main() { foo::Foo<|> } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_adt_in_other_file_via_path() {
+        check_assist(
+            change_visibility,
+            r"
+              //- /main.rs
+              mod foo;
+              fn main() { foo::Foo<|> }
+
+              //- /foo.rs
+              struct Foo;
+              ",
+            r"<|>pub(crate) struct Foo;
+
+",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_struct_field_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { pub struct Foo { bar: (), } }
+              fn main() { foo::Foo { <|>bar: () }; } ",
+            r"mod foo { pub struct Foo { <|>pub(crate) bar: (), } }
+              fn main() { foo::Foo { bar: () }; } ",
+        );
+        check_assist(
+            change_visibility,
+            r"//- /lib.rs
+              mod foo;
+              fn main() { foo::Foo { <|>bar: () }; }
+              //- /foo.rs
+              pub struct Foo { bar: () }
+              ",
+            r"pub struct Foo { <|>pub(crate) bar: () }
+
+",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub struct Foo { pub bar: (), } }
+              fn main() { foo::Foo { <|>bar: () }; } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"//- /lib.rs
+              mod foo;
+              fn main() { foo::Foo { <|>bar: () }; }
+              //- /foo.rs
+              pub struct Foo { pub bar: () }
+              ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_enum_variant_field_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { pub enum Foo { Bar { bar: () } } }
+              fn main() { foo::Foo::Bar { <|>bar: () }; } ",
+            r"mod foo { pub enum Foo { Bar { <|>pub(crate) bar: () } } }
+              fn main() { foo::Foo::Bar { bar: () }; } ",
+        );
+        check_assist(
+            change_visibility,
+            r"//- /lib.rs
+              mod foo;
+              fn main() { foo::Foo::Bar { <|>bar: () }; }
+              //- /foo.rs
+              pub enum Foo { Bar { bar: () } }
+              ",
+            r"pub enum Foo { Bar { <|>pub(crate) bar: () } }
+
+",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub struct Foo { pub bar: (), } }
+              fn main() { foo::Foo { <|>bar: () }; } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"//- /lib.rs
+              mod foo;
+              fn main() { foo::Foo { <|>bar: () }; }
+              //- /foo.rs
+              pub struct Foo { pub bar: () }
+              ",
+        );
+    }
+
+    #[test]
+    #[ignore]
+    // FIXME reenable this test when `Semantics::resolve_record_field` works with union fields
+    fn change_visibility_of_union_field_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { pub union Foo { bar: (), } }
+              fn main() { foo::Foo { <|>bar: () }; } ",
+            r"mod foo { pub union Foo { <|>pub(crate) bar: (), } }
+              fn main() { foo::Foo { bar: () }; } ",
+        );
+        check_assist(
+            change_visibility,
+            r"//- /lib.rs
+              mod foo;
+              fn main() { foo::Foo { <|>bar: () }; }
+              //- /foo.rs
+              pub union Foo { bar: () }
+              ",
+            r"pub union Foo { <|>pub(crate) bar: () }
+
+",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub union Foo { pub bar: (), } }
+              fn main() { foo::Foo { <|>bar: () }; } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"//- /lib.rs
+              mod foo;
+              fn main() { foo::Foo { <|>bar: () }; }
+              //- /foo.rs
+              pub union Foo { pub bar: () }
+              ",
+        );
+    }
+
+    #[test]
+    fn not_applicable_for_enum_variants() {
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub enum Foo {Foo1} }
+              fn main() { foo::Foo::Foo1<|> } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_const_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { const FOO: () = (); }
+              fn main() { foo::FOO<|> } ",
+            r"mod foo { <|>pub(crate) const FOO: () = (); }
+              fn main() { foo::FOO } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub const FOO: () = (); }
+              fn main() { foo::FOO<|> } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_static_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { static FOO: () = (); }
+              fn main() { foo::FOO<|> } ",
+            r"mod foo { <|>pub(crate) static FOO: () = (); }
+              fn main() { foo::FOO } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub static FOO: () = (); }
+              fn main() { foo::FOO<|> } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_trait_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { trait Foo { fn foo(&self) {} } }
+              fn main() { let x: &dyn foo::<|>Foo; } ",
+            r"mod foo { <|>pub(crate) trait Foo { fn foo(&self) {} } }
+              fn main() { let x: &dyn foo::Foo; } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub trait Foo { fn foo(&self) {} } }
+              fn main() { let x: &dyn foo::Foo<|>; } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_type_alias_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { type Foo = (); }
+              fn main() { let x: foo::Foo<|>; } ",
+            r"mod foo { <|>pub(crate) type Foo = (); }
+              fn main() { let x: foo::Foo; } ",
+        );
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub type Foo = (); }
+              fn main() { let x: foo::Foo<|>; } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_module_via_path() {
+        check_assist(
+            change_visibility,
+            r"mod foo { mod bar { fn bar() {} } }
+              fn main() { foo::bar<|>::bar(); } ",
+            r"mod foo { <|>pub(crate) mod bar { fn bar() {} } }
+              fn main() { foo::bar::bar(); } ",
+        );
+
+        check_assist(
+            change_visibility,
+            r"
+            //- /main.rs
+            mod foo;
+            fn main() { foo::bar<|>::baz(); }
+
+            //- /foo.rs
+            mod bar {
+                pub fn baz() {}
+            }
+            ",
+            r"<|>pub(crate) mod bar {
+    pub fn baz() {}
+}
+
+",
+        );
+
+        check_assist_not_applicable(
+            change_visibility,
+            r"mod foo { pub mod bar { pub fn bar() {} } }
+              fn main() { foo::bar<|>::bar(); } ",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_inline_module_in_other_file_via_path() {
+        check_assist(
+            change_visibility,
+            r"
+            //- /main.rs
+            mod foo;
+            fn main() { foo::bar<|>::baz(); }
+
+            //- /foo.rs
+            mod bar;
+
+            //- /foo/bar.rs
+            pub fn baz() {}
+            }
+            ",
+            r"<|>pub(crate) mod bar;
+",
+        );
+    }
+
+    #[test]
+    fn change_visibility_of_module_declaration_in_other_file_via_path() {
+        check_assist(
+            change_visibility,
+            r"//- /main.rs
+              mod foo;
+              fn main() { foo::bar<|>>::baz(); }
+
+              //- /foo.rs
+              mod bar {
+                  pub fn baz() {}
+              }",
+            r"<|>pub(crate) mod bar {
+    pub fn baz() {}
+}
+",
+        );
+    }
+
+    #[test]
+    #[ignore]
+    // FIXME handle reexports properly
+    fn change_visibility_of_reexport() {
+        check_assist(
+            change_visibility,
+            r"
+            mod foo {
+                use bar::Baz;
+                mod bar { pub(super) struct Baz; }
+            }
+            foo::Baz<|>
+            ",
+            r"
+            mod foo {
+                <|>pub(crate) use bar::Baz;
+                mod bar { pub(super) struct Baz; }
+            }
+            foo::Baz
+            ",
+        )
+    }
+
+    #[test]
+    fn adds_pub_when_target_is_in_another_crate() {
+        check_assist(
+            change_visibility,
+            r"//- /main.rs crate:a deps:foo
+              foo::Bar<|>
+              //- /lib.rs crate:foo
+              struct Bar;",
+            r"<|>pub struct Bar;
+",
+        )
+    }
+
+    #[test]
     fn change_visibility_target() {
         check_assist_target(change_visibility, "<|>fn foo() {}", "fn");
         check_assist_target(change_visibility, "pub(crate)<|> fn foo() {}", "pub(crate)");
diff --git a/crates/ra_assists/src/utils.rs b/crates/ra_assists/src/utils.rs
index 2f15a3f15..f3fc92ebf 100644
--- a/crates/ra_assists/src/utils.rs
+++ b/crates/ra_assists/src/utils.rs
@@ -103,7 +103,7 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
 }
 
 #[derive(Clone, Copy)]
-pub(crate) enum TryEnum {
+pub enum TryEnum {
     Result,
     Option,
 }
@@ -111,7 +111,7 @@ pub(crate) enum TryEnum {
 impl TryEnum {
     const ALL: [TryEnum; 2] = [TryEnum::Option, TryEnum::Result];
 
-    pub(crate) fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> {
+    pub fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> {
         let enum_ = match ty.as_adt() {
             Some(Adt::Enum(it)) => it,
             _ => return None,