internal: type argument parsing refactoring

crates/parser/src/grammar/generic_args.rs

@@ -26,15 +26,12 @@ pub(super) fn opt_generic_arg_list(p: &mut Parser, colon_colon_required: bool) {
 // test type_arg
 // type A = B<'static, i32, 1, { 2 }, Item=u64, true, false>;
 fn generic_arg(p: &mut Parser) {
-    let m = p.start();
     match p.current() {
-        LIFETIME_IDENT => {
-            lifetime(p);
-            m.complete(p, LIFETIME_ARG);
-        }
+        LIFETIME_IDENT => lifetime_arg(p),
         // test associated_type_bounds
         // fn print_all<T: Iterator<Item, Item::Item, Item::<true>, Item: Display, Item<'a> = Item>>(printables: T) {}
         IDENT if [T![<], T![=], T![:]].contains(&p.nth(1)) => {
+            let m = p.start();
             let path_ty = p.start();
             let path = p.start();
             let path_seg = p.start();
@@ -78,37 +75,22 @@ fn generic_arg(p: &mut Parser) {
                 }
             }
         }
-        T!['{'] => {
-            expressions::block_expr(p);
-            m.complete(p, CONST_ARG);
-        }
-        k if k.is_literal() => {
-            expressions::literal(p);
-            m.complete(p, CONST_ARG);
-        }
-        T![true] | T![false] => {
-            expressions::literal(p);
-            m.complete(p, CONST_ARG);
-        }
         // test const_generic_negated_literal
         // fn f() { S::<-1> }
-        T![-] => {
-            let lm = p.start();
-            p.bump(T![-]);
-            expressions::literal(p);
-            lm.complete(p, PREFIX_EXPR);
-            m.complete(p, CONST_ARG);
-        }
-        _ => {
-            types::type_(p);
-            m.complete(p, TYPE_ARG);
-        }
+        T!['{'] | T![true] | T![false] | T![-] => const_arg(p),
+        k if k.is_literal() => const_arg(p),
+        _ => type_arg(p),
     }
 }
 
+fn lifetime_arg(p: &mut Parser) {
+    let m = p.start();
+    lifetime(p);
+    m.complete(p, LIFETIME_ARG);
+}
+
 pub(super) fn const_arg(p: &mut Parser) {
     let m = p.start();
-    // FIXME: duplicates the code above
     match p.current() {
         T!['{'] => {
             expressions::block_expr(p);
@@ -137,3 +119,9 @@ pub(super) fn const_arg(p: &mut Parser) {
         }
     }
 }
+
+fn type_arg(p: &mut Parser) {
+    let m = p.start();
+    types::type_(p);
+    m.complete(p, TYPE_ARG);
+}

crates/syntax/test_data/parser/err/0049_double_fish.rast

@@ -0,0 +1,115 @@
+SOURCE_FILE@0..90
+  FN@0..40
+    FN_KW@0..2 "fn"
+    WHITESPACE@2..3 " "
+    NAME@3..4
+      IDENT@3..4 "f"
+    PARAM_LIST@4..6
+      L_PAREN@4..5 "("
+      R_PAREN@5..6 ")"
+    WHITESPACE@6..7 " "
+    BLOCK_EXPR@7..40
+      L_CURLY@7..8 "{"
+      WHITESPACE@8..13 "\n    "
+      EXPR_STMT@13..38
+        PATH_EXPR@13..37
+          PATH@13..37
+            PATH_SEGMENT@13..37
+              NAME_REF@13..14
+                IDENT@13..14 "S"
+              GENERIC_ARG_LIST@14..37
+                COLON2@14..16 "::"
+                L_ANGLE@16..17 "<"
+                TYPE_ARG@17..36
+                  PATH_TYPE@17..36
+                    PATH@17..28
+                      PATH_SEGMENT@17..28
+                        NAME_REF@17..21
+                          IDENT@17..21 "Item"
+                        GENERIC_ARG_LIST@21..28
+                          COLON2@21..23 "::"
+                          L_ANGLE@23..24 "<"
+                          TYPE_ARG@24..27
+                            PATH_TYPE@24..27
+                              PATH@24..27
+                                PATH_SEGMENT@24..27
+                                  NAME_REF@24..27
+                                    IDENT@24..27 "lol"
+                          R_ANGLE@27..28 ">"
+                    GENERIC_ARG_LIST@28..36
+                      COLON2@28..30 "::"
+                      L_ANGLE@30..31 "<"
+                      TYPE_ARG@31..35
+                        PATH_TYPE@31..35
+                          PATH@31..35
+                            PATH_SEGMENT@31..35
+                              NAME_REF@31..35
+                                IDENT@31..35 "nope"
+                      R_ANGLE@35..36 ">"
+                R_ANGLE@36..37 ">"
+        SEMICOLON@37..38 ";"
+      WHITESPACE@38..39 "\n"
+      R_CURLY@39..40 "}"
+  WHITESPACE@40..42 "\n\n"
+  FN@42..89
+    FN_KW@42..44 "fn"
+    WHITESPACE@44..45 " "
+    NAME@45..46
+      IDENT@45..46 "g"
+    PARAM_LIST@46..48
+      L_PAREN@46..47 "("
+      R_PAREN@47..48 ")"
+    WHITESPACE@48..49 " "
+    BLOCK_EXPR@49..89
+      L_CURLY@49..50 "{"
+      WHITESPACE@50..55 "\n    "
+      LET_STMT@55..76
+        LET_KW@55..58 "let"
+        WHITESPACE@58..59 " "
+        WILDCARD_PAT@59..60
+          UNDERSCORE@59..60 "_"
+        COLON@60..61 ":"
+        WHITESPACE@61..62 " "
+        PATH_TYPE@62..76
+          PATH@62..76
+            PATH@62..73
+              PATH_SEGMENT@62..73
+                NAME_REF@62..66
+                  IDENT@62..66 "Item"
+                GENERIC_ARG_LIST@66..73
+                  COLON2@66..68 "::"
+                  L_ANGLE@68..69 "<"
+                  TYPE_ARG@69..72
+                    PATH_TYPE@69..72
+                      PATH@69..72
+                        PATH_SEGMENT@69..72
+                          NAME_REF@69..72
+                            IDENT@69..72 "lol"
+                  R_ANGLE@72..73 ">"
+            COLON2@73..75 "::"
+            ERROR@75..76
+              L_ANGLE@75..76 "<"
+      EXPR_STMT@76..83
+        BIN_EXPR@76..83
+          PATH_EXPR@76..80
+            PATH@76..80
+              PATH_SEGMENT@76..80
+                NAME_REF@76..80
+                  IDENT@76..80 "nope"
+          R_ANGLE@80..81 ">"
+          WHITESPACE@81..82 " "
+          ERROR@82..83
+            EQ@82..83 "="
+      WHITESPACE@83..84 " "
+      EXPR_STMT@84..87
+        TUPLE_EXPR@84..86
+          L_PAREN@84..85 "("
+          R_PAREN@85..86 ")"
+        SEMICOLON@86..87 ";"
+      WHITESPACE@87..88 "\n"
+      R_CURLY@88..89 "}"
+  WHITESPACE@89..90 "\n"
+error 75..75: expected identifier
+error 76..76: expected SEMICOLON
+error 82..82: expected expression
+error 83..83: expected SEMICOLON

crates/syntax/test_data/parser/err/0049_double_fish.rs

@@ -0,0 +1,7 @@
+fn f() {
+    S::<Item::<lol>::<nope>>;
+}
+
+fn g() {
+    let _: Item::<lol>::<nope> = ();
+}