Fix parsing of parenthesized type args and RTN

crates/hir-def/src/path/lower.rs

@@ -48,7 +48,7 @@ pub(super) fn lower_path(ctx: &mut LowerCtx<'_>, mut path: ast::Path) -> Option<
                     .or_else(|| {
                         lower_generic_args_from_fn_path(
                             ctx,
-                            segment.param_list(),
+                            segment.parenthesized_arg_list(),
                             segment.ret_type(),
                         )
                     });
@@ -247,12 +247,12 @@ pub(super) fn lower_generic_args(
 /// -> Z` (which desugars to `Fn<(X, Y), Output=Z>`).
 fn lower_generic_args_from_fn_path(
     ctx: &mut LowerCtx<'_>,
-    params: Option<ast::ParamList>,
+    args: Option<ast::ParenthesizedArgList>,
     ret_type: Option<ast::RetType>,
 ) -> Option<GenericArgs> {
-    let params = params?;
+    let params = args?;
     let mut param_types = Vec::new();
-    for param in params.params() {
+    for param in params.type_args() {
         let type_ref = TypeRef::from_ast_opt(ctx, param.ty());
         param_types.push(type_ref);
     }

crates/ide-db/src/path_transform.rs

@@ -286,7 +286,8 @@ impl Ctx<'_> {
             return None;
         }
         if path.segment().map_or(false, |s| {
-            s.param_list().is_some() || (s.self_token().is_some() && path.parent_path().is_none())
+            s.parenthesized_arg_list().is_some()
+                || (s.self_token().is_some() && path.parent_path().is_none())
         }) {
             // don't try to qualify `Fn(Foo) -> Bar` paths, they are in prelude anyway
             // don't try to qualify sole `self` either, they are usually locals, but are returned as modules due to namespace clashing

crates/ide-ssr/src/matching.rs

@@ -359,8 +359,8 @@ impl<'db, 'sema> Matcher<'db, 'sema> {
                 )?;
                 self.attempt_match_opt(
                     phase,
-                    pattern_segment.param_list(),
-                    code_segment.param_list(),
+                    pattern_segment.parenthesized_arg_list(),
+                    code_segment.parenthesized_arg_list(),
                 )?;
             }
             if matches!(phase, Phase::Second(_)) {

crates/ide/src/inlay_hints/lifetime.rs

@@ -41,7 +41,15 @@ pub(super) fn fn_hints(
         fd,
         config,
         file_id,
-        param_list,
+        param_list.params().filter_map(|it| {
+            Some((
+                it.pat().and_then(|it| match it {
+                    ast::Pat::IdentPat(p) => p.name(),
+                    _ => None,
+                }),
+                it.ty()?,
+            ))
+        }),
         generic_param_list,
         ret_type,
         self_param,
@@ -90,7 +98,15 @@ pub(super) fn fn_ptr_hints(
         fd,
         config,
         file_id,
-        param_list,
+        param_list.params().filter_map(|it| {
+            Some((
+                it.pat().and_then(|it| match it {
+                    ast::Pat::IdentPat(p) => p.name(),
+                    _ => None,
+                }),
+                it.ty()?,
+            ))
+        }),
         generic_param_list,
         ret_type,
         None,
@@ -148,7 +164,7 @@ pub(super) fn fn_path_hints(
         fd,
         config,
         file_id,
-        param_list,
+        param_list.type_args().filter_map(|it| Some((None, it.ty()?))),
         generic_param_list,
         ret_type,
         None,
@@ -177,8 +193,8 @@ pub(super) fn fn_path_hints(
     )
 }
 
-fn path_as_fn(path: &ast::Path) -> Option<(ast::ParamList, Option<ast::RetType>)> {
-    path.segment().and_then(|it| it.param_list().zip(Some(it.ret_type())))
+fn path_as_fn(path: &ast::Path) -> Option<(ast::ParenthesizedArgList, Option<ast::RetType>)> {
+    path.segment().and_then(|it| it.parenthesized_arg_list().zip(Some(it.ret_type())))
 }
 
 fn hints_(
@@ -187,7 +203,7 @@ fn hints_(
     FamousDefs(_, _): &FamousDefs<'_, '_>,
     config: &InlayHintsConfig,
     _file_id: EditionedFileId,
-    param_list: ast::ParamList,
+    params: impl Iterator<Item = (Option<ast::Name>, ast::Type)>,
     generic_param_list: Option<ast::GenericParamList>,
     ret_type: Option<ast::RetType>,
     self_param: Option<ast::SelfParam>,
@@ -217,45 +233,34 @@ fn hints_(
             let is_elided = is_elided(&lifetime);
             acc.push((None, self_param.amp_token(), lifetime, is_elided));
         }
-        param_list
-            .params()
-            .filter_map(|it| {
-                Some((
-                    it.pat().and_then(|it| match it {
-                        ast::Pat::IdentPat(p) => p.name(),
-                        _ => None,
-                    }),
-                    it.ty()?,
-                ))
-            })
-            .for_each(|(name, ty)| {
-                // FIXME: check path types
-                walk_ty(&ty, &mut |ty| match ty {
-                    ast::Type::RefType(r) => {
-                        let lifetime = r.lifetime();
-                        let is_elided = is_elided(&lifetime);
-                        acc.push((name.clone(), r.amp_token(), lifetime, is_elided));
-                        false
-                    }
-                    ast::Type::FnPtrType(_) => {
+        params.for_each(|(name, ty)| {
+            // FIXME: check path types
+            walk_ty(&ty, &mut |ty| match ty {
+                ast::Type::RefType(r) => {
+                    let lifetime = r.lifetime();
+                    let is_elided = is_elided(&lifetime);
+                    acc.push((name.clone(), r.amp_token(), lifetime, is_elided));
+                    false
+                }
+                ast::Type::FnPtrType(_) => {
+                    is_trivial = false;
+                    true
+                }
+                ast::Type::PathType(t) => {
+                    if t.path()
+                        .and_then(|it| it.segment())
+                        .and_then(|it| it.parenthesized_arg_list())
+                        .is_some()
+                    {
                         is_trivial = false;
                         true
+                    } else {
+                        false
                     }
-                    ast::Type::PathType(t) => {
-                        if t.path()
-                            .and_then(|it| it.segment())
-                            .and_then(|it| it.param_list())
-                            .is_some()
-                        {
-                            is_trivial = false;
-                            true
-                        } else {
-                            false
-                        }
-                    }
-                    _ => false,
-                })
-            });
+                }
+                _ => false,
+            })
+        });
         acc
     };
 
@@ -339,7 +344,10 @@ fn hints_(
                     true
                 }
                 ast::Type::PathType(t) => {
-                    if t.path().and_then(|it| it.segment()).and_then(|it| it.param_list()).is_some()
+                    if t.path()
+                        .and_then(|it| it.segment())
+                        .and_then(|it| it.parenthesized_arg_list())
+                        .is_some()
                     {
                         is_trivial = false;
                         true

crates/parser/src/grammar/expressions.rs

@@ -525,7 +525,7 @@ fn method_call_expr<const FLOAT_RECOVERY: bool>(
         p.bump(T![.]);
     }
     name_ref(p);
-    generic_args::opt_generic_arg_list(p, true);
+    generic_args::opt_generic_arg_list_expr(p);
     if p.at(T!['(']) {
         arg_list(p);
     } else {

crates/parser/src/grammar/generic_args.rs

@@ -1,14 +1,13 @@
 use super::*;
 
-// test_err generic_arg_list_recover
-// type T = T<0, ,T>;
-pub(super) fn opt_generic_arg_list(p: &mut Parser<'_>, colon_colon_required: bool) {
+// test_err generic_arg_list_recover_expr
+// const _: () = T::<0, ,T>;
+// const _: () = T::<0, ,T>();
+pub(super) fn opt_generic_arg_list_expr(p: &mut Parser<'_>) {
     let m;
     if p.at(T![::]) && p.nth(2) == T![<] {
         m = p.start();
         p.bump(T![::]);
-    } else if !colon_colon_required && p.at(T![<]) && p.nth(1) != T![=] {
-        m = p.start();
     } else {
         return;
     }
@@ -25,7 +24,7 @@ pub(super) fn opt_generic_arg_list(p: &mut Parser<'_>, colon_colon_required: boo
     m.complete(p, GENERIC_ARG_LIST);
 }
 
-const GENERIC_ARG_FIRST: TokenSet = TokenSet::new(&[
+pub(crate) const GENERIC_ARG_FIRST: TokenSet = TokenSet::new(&[
     LIFETIME_IDENT,
     IDENT,
     T!['{'],
@@ -47,20 +46,23 @@ const GENERIC_ARG_RECOVERY_SET: TokenSet = TokenSet::new(&[T![>], T![,]]);
 
 // test generic_arg
 // type T = S<i32>;
-fn generic_arg(p: &mut Parser<'_>) -> bool {
+pub(crate) fn generic_arg(p: &mut Parser<'_>) -> bool {
     match p.current() {
         LIFETIME_IDENT if !p.nth_at(1, T![+]) => lifetime_arg(p),
         T!['{'] | T![true] | T![false] | T![-] => const_arg(p),
         k if k.is_literal() => const_arg(p),
-        // test associated_type_bounds
-        // fn print_all<T: Iterator<Item, Item::Item, Item::<true>, Item: Display, Item<'a> = Item>>(printables: T) {}
+        // test generic_arg_bounds
+        // type Plain = Foo<Item, Item::Item, Item: Bound, Item = Item>;
+        // type GenericArgs = Foo<Item<T>, Item::<T>, Item<T>: Bound, Item::<T>: Bound, Item<T> = Item, Item::<T> = Item>;
+        // type ParenthesizedArgs = Foo<Item(T), Item::(T), Item(T): Bound, Item::(T): Bound, Item(T) = Item, Item::(T) = Item>;
+        // type RTN = Foo<Item(..), Item(..), Item(..): Bound, Item(..): Bound, Item(..) = Item, Item(..) = Item>;
 
         // test macro_inside_generic_arg
         // type A = Foo<syn::Token![_]>;
-        IDENT if [T![<], T![=], T![:]].contains(&p.nth(1)) && !p.nth_at(1, T![::]) => {
+        IDENT => {
             let m = p.start();
             name_ref(p);
-            opt_generic_arg_list(p, false);
+            paths::opt_path_type_args(p);
             match p.current() {
                 T![=] => {
                     p.bump_any();
@@ -88,45 +90,26 @@ fn generic_arg(p: &mut Parser<'_>) -> bool {
                 }
                 // test assoc_type_bound
                 // type T = StreamingIterator<Item<'a>: Clone>;
+                // type T = StreamingIterator<Item(T): Clone>;
                 T![:] if !p.at(T![::]) => {
                     generic_params::bounds(p);
                     m.complete(p, ASSOC_TYPE_ARG);
                 }
+                // Turned out to be just a normal path type (mirror `path_or_macro_type`)
                 _ => {
                     let m = m.complete(p, PATH_SEGMENT).precede(p).complete(p, PATH);
                     let m = paths::type_path_for_qualifier(p, m);
-                    m.precede(p).complete(p, PATH_TYPE).precede(p).complete(p, TYPE_ARG);
+                    let m = if p.at(T![!]) && !p.at(T![!=]) {
+                        let m = m.precede(p);
+                        items::macro_call_after_excl(p);
+                        m.complete(p, MACRO_CALL).precede(p).complete(p, MACRO_TYPE)
+                    } else {
+                        m.precede(p).complete(p, PATH_TYPE)
+                    };
+                    types::opt_type_bounds_as_dyn_trait_type(p, m).precede(p).complete(p, TYPE_ARG);
                 }
             }
         }
-        IDENT if p.nth_at(1, T!['(']) => {
-            let m = p.start();
-            name_ref(p);
-            if p.nth_at(1, T![..]) {
-                let rtn = p.start();
-                p.bump(T!['(']);
-                p.bump(T![..]);
-                p.expect(T![')']);
-                rtn.complete(p, RETURN_TYPE_SYNTAX);
-                // test return_type_syntax_assoc_type_bound
-                // fn foo<T: Trait<method(..): Send>>() {}
-                generic_params::bounds(p);
-                m.complete(p, ASSOC_TYPE_ARG);
-            } else {
-                params::param_list_fn_trait(p);
-                // test bare_dyn_types_with_paren_as_generic_args
-                // type A = S<Fn(i32)>;
-                // type A = S<Fn(i32) + Send>;
-                // type B = S<Fn(i32) -> i32>;
-                // type C = S<Fn(i32) -> i32 + Send>;
-                opt_ret_type(p);
-                let m = m.complete(p, PATH_SEGMENT).precede(p).complete(p, PATH);
-                let m = paths::type_path_for_qualifier(p, m);
-                let m = m.precede(p).complete(p, PATH_TYPE);
-                let m = types::opt_type_bounds_as_dyn_trait_type(p, m);
-                m.precede(p).complete(p, TYPE_ARG);
-            }
-        }
         _ if p.at_ts(types::TYPE_FIRST) => type_arg(p),
         _ => return false,
     }
@@ -190,7 +173,7 @@ pub(super) fn const_arg(p: &mut Parser<'_>) {
     m.complete(p, CONST_ARG);
 }
 
-fn type_arg(p: &mut Parser<'_>) {
+pub(crate) fn type_arg(p: &mut Parser<'_>) {
     let m = p.start();
     types::type_(p);
     m.complete(p, TYPE_ARG);

crates/parser/src/grammar/params.rs

@@ -14,12 +14,6 @@ pub(super) fn param_list_fn_def(p: &mut Parser<'_>) {
     list_(p, Flavor::FnDef);
 }
 
-// test param_list_opt_patterns
-// fn foo<F: FnMut(&mut Foo<'a>)>(){}
-pub(super) fn param_list_fn_trait(p: &mut Parser<'_>) {
-    list_(p, Flavor::FnTrait);
-}
-
 pub(super) fn param_list_fn_ptr(p: &mut Parser<'_>) {
     list_(p, Flavor::FnPointer);
 }
@@ -28,10 +22,9 @@ pub(super) fn param_list_closure(p: &mut Parser<'_>) {
     list_(p, Flavor::Closure);
 }
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 enum Flavor {
-    FnDef,   // Includes trait fn params; omitted param idents are not supported
-    FnTrait, // Params for `Fn(...)`/`FnMut(...)`/`FnOnce(...)` annotations
+    FnDef, // Includes trait fn params; omitted param idents are not supported
     FnPointer,
     Closure,
 }
@@ -41,7 +34,7 @@ fn list_(p: &mut Parser<'_>, flavor: Flavor) {
 
     let (bra, ket) = match flavor {
         Closure => (T![|], T![|]),
-        FnDef | FnTrait | FnPointer => (T!['('], T![')']),
+        FnDef | FnPointer => (T!['('], T![')']),
     };
 
     let list_marker = p.start();
@@ -119,11 +112,6 @@ fn param(p: &mut Parser<'_>, m: Marker, flavor: Flavor) {
                 }
             }
         }
-        // test value_parameters_no_patterns
-        // type F = Box<Fn(i32, &i32, &i32, ())>;
-        Flavor::FnTrait => {
-            types::type_(p);
-        }
         // test fn_pointer_param_ident_path
         // type Foo = fn(Bar::Baz);
         // type Qux = fn(baz: Bar::Baz);