Fix Return Type Syntax to include .. (i.e. method(..) and not method()) as specified in the RFC

crates/parser/src/grammar/generic_args.rs

@@ -102,13 +102,18 @@ fn generic_arg(p: &mut Parser<'_>) -> bool {
         IDENT if p.nth_at(1, T!['(']) => {
             let m = p.start();
             name_ref(p);
-            params::param_list_fn_trait(p);
+            if p.nth_at(1, T![..]) {
-            if p.at(T![:]) && !p.at(T![::]) {
+                let rtn = p.start();
-                // test associated_return_type_bounds
+                p.bump(T!['(']);
-                // fn foo<T: Foo<foo(): Send, bar(i32): Send, baz(i32, i32): Send>>() {}
+                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>;

crates/parser/src/grammar/generic_params.rs

@@ -119,8 +119,7 @@ fn lifetime_bounds(p: &mut Parser<'_>) {
 // test type_param_bounds
 // struct S<T: 'a + ?Sized + (Copy) + ~const Drop>;
 pub(super) fn bounds(p: &mut Parser<'_>) {
-    assert!(p.at(T![:]));
+    p.expect(T![:]);
-    p.bump(T![:]);
     bounds_without_colon(p);
 }
 

crates/parser/src/grammar/paths.rs

@@ -140,11 +140,24 @@ fn opt_path_type_args(p: &mut Parser<'_>, mode: Mode) {
             if p.at(T![::]) && p.nth_at(2, T!['(']) {
                 p.bump(T![::]);
             }
-            // test path_fn_trait_args
-            // type F = Box<Fn(i32) -> ()>;
             if p.at(T!['(']) {
-                params::param_list_fn_trait(p);
+                if p.nth_at(1, T![..]) {
-                opt_ret_type(p);
+                    // test return_type_syntax_in_path
+                    // fn foo<T>()
+                    // where
+                    //     T::method(..): Send,
+                    // {}
+                    let rtn = p.start();
+                    p.bump(T!['(']);
+                    p.bump(T![..]);
+                    p.expect(T![')']);
+                    rtn.complete(p, RETURN_TYPE_SYNTAX);
+                } else {
+                    // test path_fn_trait_args
+                    // type F = Box<Fn(i32) -> ()>;
+                    params::param_list_fn_trait(p);
+                    opt_ret_type(p);
+                }
             } else {
                 generic_args::opt_generic_arg_list(p, false);
             }

crates/parser/src/syntax_kind/generated.rs

@@ -253,6 +253,7 @@ pub enum SyntaxKind {
     RENAME,
     REST_PAT,
     RETURN_EXPR,
+    RETURN_TYPE_SYNTAX,
     RET_TYPE,
     SELF_PARAM,
     SLICE_PAT,

crates/parser/test_data/generated/runner.rs

@@ -37,10 +37,6 @@ mod ok {
     #[test]
     fn assoc_type_eq() { run_and_expect_no_errors("test_data/parser/inline/ok/assoc_type_eq.rs"); }
     #[test]
-    fn associated_return_type_bounds() {
-        run_and_expect_no_errors("test_data/parser/inline/ok/associated_return_type_bounds.rs");
-    }
-    #[test]
     fn associated_type_bounds() {
         run_and_expect_no_errors("test_data/parser/inline/ok/associated_type_bounds.rs");
     }
@@ -519,6 +515,16 @@ mod ok {
     #[test]
     fn return_expr() { run_and_expect_no_errors("test_data/parser/inline/ok/return_expr.rs"); }
     #[test]
+    fn return_type_syntax_assoc_type_bound() {
+        run_and_expect_no_errors(
+            "test_data/parser/inline/ok/return_type_syntax_assoc_type_bound.rs",
+        );
+    }
+    #[test]
+    fn return_type_syntax_in_path() {
+        run_and_expect_no_errors("test_data/parser/inline/ok/return_type_syntax_in_path.rs");
+    }
+    #[test]
     fn self_param() { run_and_expect_no_errors("test_data/parser/inline/ok/self_param.rs"); }
     #[test]
     fn self_param_outer_attr() {

crates/parser/test_data/parser/inline/ok/associated_return_type_bounds.rs

@@ -1 +0,0 @@
-fn foo<T: Foo<foo(): Send, bar(i32): Send, baz(i32, i32): Send>>() {}

crates/parser/test_data/parser/inline/ok/return_type_syntax_assoc_type_bound.rast

@@ -0,0 +1,49 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    GENERIC_PARAM_LIST
+      L_ANGLE "<"
+      TYPE_PARAM
+        NAME
+          IDENT "T"
+        COLON ":"
+        WHITESPACE " "
+        TYPE_BOUND_LIST
+          TYPE_BOUND
+            PATH_TYPE
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "Trait"
+                  GENERIC_ARG_LIST
+                    L_ANGLE "<"
+                    ASSOC_TYPE_ARG
+                      NAME_REF
+                        IDENT "method"
+                      RETURN_TYPE_SYNTAX
+                        L_PAREN "("
+                        DOT2 ".."
+                        R_PAREN ")"
+                      COLON ":"
+                      WHITESPACE " "
+                      TYPE_BOUND_LIST
+                        TYPE_BOUND
+                          PATH_TYPE
+                            PATH
+                              PATH_SEGMENT
+                                NAME_REF
+                                  IDENT "Send"
+                    R_ANGLE ">"
+      R_ANGLE ">"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n"

crates/parser/test_data/parser/inline/ok/return_type_syntax_assoc_type_bound.rs

@@ -0,0 +1 @@
+fn foo<T: Trait<method(..): Send>>() {}

crates/parser/test_data/parser/inline/ok/return_type_syntax_in_path.rast

@@ -0,0 +1,50 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    GENERIC_PARAM_LIST
+      L_ANGLE "<"
+      TYPE_PARAM
+        NAME
+          IDENT "T"
+      R_ANGLE ">"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE "\n"
+    WHERE_CLAUSE
+      WHERE_KW "where"
+      WHITESPACE "\n    "
+      WHERE_PRED
+        PATH_TYPE
+          PATH
+            PATH
+              PATH_SEGMENT
+                NAME_REF
+                  IDENT "T"
+            COLON2 "::"
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "method"
+              RETURN_TYPE_SYNTAX
+                L_PAREN "("
+                DOT2 ".."
+                R_PAREN ")"
+        COLON ":"
+        WHITESPACE " "
+        TYPE_BOUND_LIST
+          TYPE_BOUND
+            PATH_TYPE
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "Send"
+      COMMA ","
+    WHITESPACE "\n"
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n"

crates/parser/test_data/parser/inline/ok/return_type_syntax_in_path.rs

@@ -0,0 +1,4 @@
+fn foo<T>()
+where
+    T::method(..): Send,
+{}

crates/syntax/rust.ungram

@@ -38,8 +38,12 @@ PathSegment =
   '::'? NameRef
 | NameRef GenericArgList?
 | NameRef ParamList RetType?
+| NameRef ReturnTypeSyntax
 | '<' Type ('as' PathType)? '>'
 
+ReturnTypeSyntax =
+  '(' '..' ')'
+
 
 //*************************//
 //        Generics         //
@@ -59,7 +63,7 @@ TypeArg =
 
 AssocTypeArg =
   NameRef
-  (GenericArgList | ParamList RetType?)?
+  (GenericArgList | ParamList RetType? | ReturnTypeSyntax)?
   (':' TypeBoundList | ('=' Type | ConstArg))
 
 LifetimeArg =

crates/syntax/src/ast/generated/nodes.rs

@@ -114,6 +114,8 @@ impl AssocTypeArg {
     #[inline]
     pub fn ret_type(&self) -> Option<RetType> { support::child(&self.syntax) }
     #[inline]
+    pub fn return_type_syntax(&self) -> Option<ReturnTypeSyntax> { support::child(&self.syntax) }
+    #[inline]
     pub fn ty(&self) -> Option<Type> { support::child(&self.syntax) }
     #[inline]
     pub fn eq_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![=]) }
@@ -1221,6 +1223,8 @@ impl PathSegment {
     #[inline]
     pub fn ret_type(&self) -> Option<RetType> { support::child(&self.syntax) }
     #[inline]
+    pub fn return_type_syntax(&self) -> Option<ReturnTypeSyntax> { support::child(&self.syntax) }
+    #[inline]
     pub fn ty(&self) -> Option<Type> { support::child(&self.syntax) }
     #[inline]
     pub fn coloncolon_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![::]) }
@@ -1485,6 +1489,19 @@ impl ReturnExpr {
     pub fn return_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![return]) }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ReturnTypeSyntax {
+    pub(crate) syntax: SyntaxNode,
+}
+impl ReturnTypeSyntax {
+    #[inline]
+    pub fn l_paren_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T!['(']) }
+    #[inline]
+    pub fn r_paren_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![')']) }
+    #[inline]
+    pub fn dotdot_token(&self) -> Option<SyntaxToken> { support::token(&self.syntax, T![..]) }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct SelfParam {
     pub(crate) syntax: SyntaxNode,
@@ -3697,6 +3714,20 @@ impl AstNode for ReturnExpr {
     #[inline]
     fn syntax(&self) -> &SyntaxNode { &self.syntax }
 }
+impl AstNode for ReturnTypeSyntax {
+    #[inline]
+    fn can_cast(kind: SyntaxKind) -> bool { kind == RETURN_TYPE_SYNTAX }
+    #[inline]
+    fn cast(syntax: SyntaxNode) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    #[inline]
+    fn syntax(&self) -> &SyntaxNode { &self.syntax }
+}
 impl AstNode for SelfParam {
     #[inline]
     fn can_cast(kind: SyntaxKind) -> bool { kind == SELF_PARAM }
@@ -6609,6 +6640,11 @@ impl std::fmt::Display for ReturnExpr {
         std::fmt::Display::fmt(self.syntax(), f)
     }
 }
+impl std::fmt::Display for ReturnTypeSyntax {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        std::fmt::Display::fmt(self.syntax(), f)
+    }
+}
 impl std::fmt::Display for SelfParam {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         std::fmt::Display::fmt(self.syntax(), f)