move pat to prefix entry points

3 files changed, 17 insertions, 5 deletions

diff --git a/crates/mbe/src/expander/matcher.rs b/crates/mbe/src/expander/matcher.rs
index b5d1e098c4f..03ada8b2b9c 100644
--- a/crates/mbe/src/expander/matcher.rs
+++ b/crates/mbe/src/expander/matcher.rs
@@ -693,7 +693,14 @@ fn match_meta_var(kind: &str, input: &mut TtIter) -> ExpandResult<Option<Fragmen
         "path" => ParserEntryPoint::Path,
         "expr" => ParserEntryPoint::Expr,
         "ty" => ParserEntryPoint::Type,
-        "pat" | "pat_param" => ParserEntryPoint::Pattern, // FIXME: edition2021
+        // FIXME: These two should actually behave differently depending on the edition.
+        //
+        // https://doc.rust-lang.org/edition-guide/rust-2021/or-patterns-macro-rules.html
+        "pat" | "pat_param" => {
+            return input
+                .expect_fragment2(parser::PrefixEntryPoint::Pat)
+                .map(|tt| tt.map(Fragment::Tokens));
+        }
         "stmt" => {
             return input
                 .expect_fragment2(parser::PrefixEntryPoint::Stmt)
diff --git a/crates/parser/src/grammar.rs b/crates/parser/src/grammar.rs
index f15272ce870..4c6106f18a8 100644
--- a/crates/parser/src/grammar.rs
+++ b/crates/parser/src/grammar.rs
@@ -61,6 +61,10 @@ pub(crate) mod entry {
         pub(crate) fn stmt(p: &mut Parser) {
             expressions::stmt(p, expressions::StmtWithSemi::No, true);
         }
+
+        pub(crate) fn pat(p: &mut Parser) {
+            patterns::pattern_single(p);
+        }
     }
 }
 
@@ -76,8 +80,6 @@ pub(crate) mod entry_points {
 
     pub(crate) use paths::type_path as path;
 
-    pub(crate) use patterns::pattern_single as pattern;
-
     pub(crate) use types::type_;
 
     pub(crate) fn expr(p: &mut Parser) {
diff --git a/crates/parser/src/lib.rs b/crates/parser/src/lib.rs
index 97b717346b1..a6e554c3b45 100644
--- a/crates/parser/src/lib.rs
+++ b/crates/parser/src/lib.rs
@@ -43,7 +43,8 @@ pub use crate::{
 
 /// Parse a syntactic construct at the *start* of the input.
 ///
-/// This is used by macro-by-example parser to implement things like `$i:item`.
+/// This is used by macro-by-example parser to implement things like `$i:item`
+/// and the naming of variants follows the naming of macro fragments.
 ///
 /// Note that this is generally non-optional -- the result is intentionally not
 /// `Option<Output>`. The way MBE work, by the time we *try* to parse `$e:expr`
@@ -54,6 +55,7 @@ pub enum PrefixEntryPoint {
     Vis,
     Block,
     Stmt,
+    Pat,
 }
 
 impl PrefixEntryPoint {
@@ -62,6 +64,7 @@ impl PrefixEntryPoint {
             PrefixEntryPoint::Vis => grammar::entry::prefix::vis,
             PrefixEntryPoint::Block => grammar::entry::prefix::block,
             PrefixEntryPoint::Stmt => grammar::entry::prefix::stmt,
+            PrefixEntryPoint::Pat => grammar::entry::prefix::pat,
         };
         let mut p = parser::Parser::new(input);
         entry_point(&mut p);
@@ -108,7 +111,7 @@ pub fn parse(inp: &Input, entry_point: ParserEntryPoint) -> Output {
         ParserEntryPoint::Path => grammar::entry_points::path,
         ParserEntryPoint::Expr => grammar::entry_points::expr,
         ParserEntryPoint::Type => grammar::entry_points::type_,
-        ParserEntryPoint::Pattern => grammar::entry_points::pattern,
+        ParserEntryPoint::Pattern => grammar::entry::prefix::pat,
         ParserEntryPoint::Item => grammar::entry_points::item,
         ParserEntryPoint::MetaItem => grammar::entry_points::meta_item,
         ParserEntryPoint::StatementOptionalSemi => grammar::entry_points::stmt_optional_semi,