Parse contextual dyn keyword properly in edition 2015

crates/mbe/src/to_parser_input.rs

@@ -65,9 +65,8 @@ pub(crate) fn to_parser_input<S: Copy + fmt::Debug>(
                         i if i.starts_with('\'') => res.push(LIFETIME_IDENT),
                         _ if ident.is_raw.yes() => res.push(IDENT),
                         "gen" if !edition.at_least_2024() => res.push(IDENT),
-                        "async" | "await" | "dyn" | "try" if !edition.at_least_2018() => {
+                        "dyn" if !edition.at_least_2018() => res.push_ident(DYN_KW),
-                            res.push(IDENT)
+                        "async" | "await" | "try" if !edition.at_least_2018() => res.push(IDENT),
-                        }
                         text => match SyntaxKind::from_keyword(text) {
                             Some(kind) => res.push(kind),
                             None => {

crates/parser/src/grammar/paths.rs

@@ -2,6 +2,8 @@ use super::*;
 
 pub(super) const PATH_FIRST: TokenSet =
     TokenSet::new(&[IDENT, T![self], T![super], T![crate], T![Self], T![:], T![<]]);
+pub(super) const WEAK_DYN_PATH_FIRST: TokenSet =
+    TokenSet::new(&[IDENT, T![self], T![super], T![crate], T![Self]]);
 
 pub(super) fn is_path_start(p: &Parser<'_>) -> bool {
     is_use_path_start(p) || p.at(T![<]) || p.at(T![Self])

crates/parser/src/grammar/types.rs

@@ -1,3 +1,5 @@
+use crate::grammar::paths::WEAK_DYN_PATH_FIRST;
+
 use super::*;
 
 pub(super) const TYPE_FIRST: TokenSet = paths::PATH_FIRST.union(TokenSet::new(&[
@@ -49,6 +51,13 @@ fn type_with_bounds_cond(p: &mut Parser<'_>, allow_bounds: bool) {
         T![dyn] => dyn_trait_type(p),
         // Some path types are not allowed to have bounds (no plus)
         T![<] => path_type_bounds(p, allow_bounds),
+        T![ident]
+            if !p.edition().at_least_2018()
+                && p.at_contextual_kw(T![dyn])
+                && WEAK_DYN_PATH_FIRST.contains(p.nth(1)) =>
+        {
+            dyn_trait_type_weak(p)
+        }
         _ if paths::is_path_start(p) => path_or_macro_type_(p, allow_bounds),
         LIFETIME_IDENT if p.nth_at(1, T![+]) => bare_dyn_trait_type(p),
         _ => {
@@ -279,6 +288,18 @@ fn dyn_trait_type(p: &mut Parser<'_>) {
     m.complete(p, DYN_TRAIT_TYPE);
 }
 
+// test dyn_trait_type_weak 2015
+// type A = dyn Iterator<Item=Foo<'a>> + 'a;
+// type A = &dyn Iterator<Item=Foo<'a>> + 'a;
+// type A = dyn::Path;
+fn dyn_trait_type_weak(p: &mut Parser<'_>) {
+    assert!(p.at_contextual_kw(T![dyn]));
+    let m = p.start();
+    p.bump_remap(T![dyn]);
+    generic_params::bounds_without_colon(p);
+    m.complete(p, DYN_TRAIT_TYPE);
+}
+
 // test bare_dyn_types_with_leading_lifetime
 // type A = 'static + Trait;
 // type B = S<'static + Trait>;

crates/parser/src/parser.rs

@@ -27,14 +27,14 @@ pub(crate) struct Parser<'t> {
     pos: usize,
     events: Vec<Event>,
     steps: Cell<u32>,
-    _edition: Edition,
+    edition: Edition,
 }
 
 static PARSER_STEP_LIMIT: Limit = Limit::new(15_000_000);
 
 impl<'t> Parser<'t> {
     pub(super) fn new(inp: &'t Input, edition: Edition) -> Parser<'t> {
-        Parser { inp, pos: 0, events: Vec::new(), steps: Cell::new(0), _edition: edition }
+        Parser { inp, pos: 0, events: Vec::new(), steps: Cell::new(0), edition: edition }
     }
 
     pub(crate) fn finish(self) -> Vec<Event> {
@@ -277,6 +277,10 @@ impl<'t> Parser<'t> {
     fn push_event(&mut self, event: Event) {
         self.events.push(event);
     }
+
+    pub(crate) fn edition(&self) -> Edition {
+        self.edition
+    }
 }
 
 /// See [`Parser::start`].

crates/parser/src/shortcuts.rs

@@ -12,7 +12,7 @@
 use std::mem;
 
 use crate::{
-    LexedStr, Step,
+    Edition, LexedStr, Step,
     SyntaxKind::{self, *},
 };
 
@@ -25,7 +25,7 @@ pub enum StrStep<'a> {
 }
 
 impl LexedStr<'_> {
-    pub fn to_input(&self) -> crate::Input {
+    pub fn to_input(&self, edition: Edition) -> crate::Input {
         let _p = tracing::info_span!("LexedStr::to_input").entered();
         let mut res = crate::Input::default();
         let mut was_joint = false;
@@ -35,8 +35,11 @@ impl LexedStr<'_> {
                 was_joint = false
             } else if kind == SyntaxKind::IDENT {
                 let token_text = self.text(i);
-                let contextual_kw =
+                let contextual_kw = if !edition.at_least_2018() && token_text == "dyn" {
-                    SyntaxKind::from_contextual_keyword(token_text).unwrap_or(SyntaxKind::IDENT);
+                    SyntaxKind::DYN_KW
+                } else {
+                    SyntaxKind::from_contextual_keyword(token_text).unwrap_or(SyntaxKind::IDENT)
+                };
                 res.push_ident(contextual_kw);
             } else {
                 if was_joint {

crates/parser/src/tests.rs

@@ -70,7 +70,7 @@ fn parse_err() {
 
 fn parse(entry: TopEntryPoint, text: &str, edition: Edition) -> (String, bool) {
     let lexed = LexedStr::new(edition, text);
-    let input = lexed.to_input();
+    let input = lexed.to_input(edition);
     let output = entry.parse(&input, edition);
 
     let mut buf = String::new();

crates/parser/src/tests/prefix_entries.rs

@@ -83,7 +83,7 @@ fn meta_item() {
 #[track_caller]
 fn check(entry: PrefixEntryPoint, input: &str, prefix: &str) {
     let lexed = LexedStr::new(Edition::CURRENT, input);
-    let input = lexed.to_input();
+    let input = lexed.to_input(Edition::CURRENT);
 
     let mut n_tokens = 0;
     for step in entry.parse(&input, Edition::CURRENT).iter() {

crates/parser/test_data/generated/runner.rs

@@ -195,6 +195,13 @@ mod ok {
         run_and_expect_no_errors("test_data/parser/inline/ok/dyn_trait_type.rs");
     }
     #[test]
+    fn dyn_trait_type_weak() {
+        run_and_expect_no_errors_with_edition(
+            "test_data/parser/inline/ok/dyn_trait_type_weak.rs",
+            crate::Edition::Edition2015,
+        );
+    }
+    #[test]
     fn effect_blocks() { run_and_expect_no_errors("test_data/parser/inline/ok/effect_blocks.rs"); }
     #[test]
     fn exclusive_range_pat() {

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

@@ -0,0 +1,113 @@
+SOURCE_FILE
+  TYPE_ALIAS
+    COMMENT "// 2015"
+    WHITESPACE "\n"
+    TYPE_KW "type"
+    WHITESPACE " "
+    NAME
+      IDENT "A"
+    WHITESPACE " "
+    EQ "="
+    WHITESPACE " "
+    DYN_TRAIT_TYPE
+      DYN_KW "dyn"
+      WHITESPACE " "
+      TYPE_BOUND_LIST
+        TYPE_BOUND
+          PATH_TYPE
+            PATH
+              PATH_SEGMENT
+                NAME_REF
+                  IDENT "Iterator"
+                GENERIC_ARG_LIST
+                  L_ANGLE "<"
+                  ASSOC_TYPE_ARG
+                    NAME_REF
+                      IDENT "Item"
+                    EQ "="
+                    PATH_TYPE
+                      PATH
+                        PATH_SEGMENT
+                          NAME_REF
+                            IDENT "Foo"
+                          GENERIC_ARG_LIST
+                            L_ANGLE "<"
+                            LIFETIME_ARG
+                              LIFETIME
+                                LIFETIME_IDENT "'a"
+                            R_ANGLE ">"
+                  R_ANGLE ">"
+        WHITESPACE " "
+        PLUS "+"
+        WHITESPACE " "
+        TYPE_BOUND
+          LIFETIME
+            LIFETIME_IDENT "'a"
+    SEMICOLON ";"
+  WHITESPACE "\n"
+  TYPE_ALIAS
+    TYPE_KW "type"
+    WHITESPACE " "
+    NAME
+      IDENT "A"
+    WHITESPACE " "
+    EQ "="
+    WHITESPACE " "
+    REF_TYPE
+      AMP "&"
+      DYN_TRAIT_TYPE
+        DYN_KW "dyn"
+        WHITESPACE " "
+        TYPE_BOUND_LIST
+          TYPE_BOUND
+            PATH_TYPE
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "Iterator"
+                  GENERIC_ARG_LIST
+                    L_ANGLE "<"
+                    ASSOC_TYPE_ARG
+                      NAME_REF
+                        IDENT "Item"
+                      EQ "="
+                      PATH_TYPE
+                        PATH
+                          PATH_SEGMENT
+                            NAME_REF
+                              IDENT "Foo"
+                            GENERIC_ARG_LIST
+                              L_ANGLE "<"
+                              LIFETIME_ARG
+                                LIFETIME
+                                  LIFETIME_IDENT "'a"
+                              R_ANGLE ">"
+                    R_ANGLE ">"
+          WHITESPACE " "
+          PLUS "+"
+          WHITESPACE " "
+          TYPE_BOUND
+            LIFETIME
+              LIFETIME_IDENT "'a"
+    SEMICOLON ";"
+  WHITESPACE "\n"
+  TYPE_ALIAS
+    TYPE_KW "type"
+    WHITESPACE " "
+    NAME
+      IDENT "A"
+    WHITESPACE " "
+    EQ "="
+    WHITESPACE " "
+    PATH_TYPE
+      PATH
+        PATH
+          PATH_SEGMENT
+            NAME_REF
+              IDENT "dyn"
+        COLON2 "::"
+        PATH_SEGMENT
+          NAME_REF
+            IDENT "Path"
+    SEMICOLON ";"
+  WHITESPACE "\n"

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

@@ -0,0 +1,4 @@
+// 2015
+type A = dyn Iterator<Item=Foo<'a>> + 'a;
+type A = &dyn Iterator<Item=Foo<'a>> + 'a;
+type A = dyn::Path;