fix: Improve parser recovery a bit

crates/hir-def/src/macro_expansion_tests/builtin_fn_macro.rs

@@ -285,8 +285,6 @@ fn main() {
     /* parse error: expected expression */
 builtin #format_args (x = );
     /* parse error: expected expression */
-/* parse error: expected R_PAREN */
-/* parse error: expected expression, item or let statement */
 builtin #format_args (x = , x = 2);
     /* parse error: expected expression */
 builtin #format_args ("{}", x = );

crates/ide-completion/src/context/analysis.rs

@@ -661,9 +661,8 @@ fn expected_type_and_name(
                             ))
                         } else {
                             cov_mark::hit!(expected_type_struct_field_without_leading_char);
-                            let expr_field = token.prev_sibling_or_token()?
-                                .into_node()
-                                .and_then(ast::RecordExprField::cast)?;
+                            cov_mark::hit!(expected_type_struct_field_followed_by_comma);
+                            let expr_field = previous_non_trivia_token(token.clone())?.parent().and_then(ast::RecordExprField::cast)?;
                             let (_, _, ty) = sema.resolve_record_field(&expr_field)?;
                             Some((
                                 Some(ty),
@@ -681,7 +680,6 @@ fn expected_type_and_name(
                             .or_else(|| sema.type_of_expr(&expr).map(TypeInfo::original));
                         (ty, field_name)
                     } else {
-                        cov_mark::hit!(expected_type_struct_field_followed_by_comma);
                         (field_ty, field_name)
                     }
                 },

crates/parser/src/grammar/expressions.rs

@@ -4,7 +4,7 @@ use crate::grammar::attributes::ATTRIBUTE_FIRST;
 
 use super::*;
 
-pub(super) use atom::{LITERAL_FIRST, literal};
+pub(super) use atom::{EXPR_RECOVERY_SET, LITERAL_FIRST, literal};
 pub(crate) use atom::{block_expr, match_arm_list};
 
 #[derive(PartialEq, Eq)]

crates/parser/src/grammar/expressions/atom.rs

@@ -46,7 +46,6 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         T!['['],
         T![|],
         T![async],
-        T![box],
         T![break],
         T![const],
         T![continue],
@@ -68,7 +67,8 @@ pub(super) const ATOM_EXPR_FIRST: TokenSet =
         LIFETIME_IDENT,
     ]));
 
-pub(super) const EXPR_RECOVERY_SET: TokenSet = TokenSet::new(&[T![')'], T![']']]);
+pub(in crate::grammar) const EXPR_RECOVERY_SET: TokenSet =
+    TokenSet::new(&[T!['}'], T![')'], T![']'], T![,]]);
 
 pub(super) fn atom_expr(
     p: &mut Parser<'_>,

crates/parser/src/grammar/items.rs

@@ -32,6 +32,9 @@ pub(super) const ITEM_RECOVERY_SET: TokenSet = TokenSet::new(&[
     T![impl],
     T![trait],
     T![const],
+    T![async],
+    T![unsafe],
+    T![extern],
     T![static],
     T![let],
     T![mod],

crates/parser/src/grammar/paths.rs

@@ -81,7 +81,7 @@ fn path_for_qualifier(
 }
 
 const EXPR_PATH_SEGMENT_RECOVERY_SET: TokenSet =
-    items::ITEM_RECOVERY_SET.union(TokenSet::new(&[T![')'], T![,], T![let]]));
+    expressions::EXPR_RECOVERY_SET.union(items::ITEM_RECOVERY_SET);
 const TYPE_PATH_SEGMENT_RECOVERY_SET: TokenSet = types::TYPE_RECOVERY_SET;
 
 fn path_segment(p: &mut Parser<'_>, mode: Mode, first: bool) -> Option<CompletedMarker> {

crates/parser/src/grammar/patterns.rs

@@ -199,8 +199,19 @@ fn pattern_single_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
     }
 }
 
-const PAT_RECOVERY_SET: TokenSet =
-    TokenSet::new(&[T![let], T![if], T![while], T![loop], T![match], T![')'], T![,], T![=]]);
+const PAT_RECOVERY_SET: TokenSet = TokenSet::new(&[
+    T![let],
+    T![if],
+    T![while],
+    T![loop],
+    T![match],
+    T![')'],
+    T![']'],
+    T!['}'],
+    T![,],
+    T![=],
+    T![&],
+]);
 
 fn atom_pat(p: &mut Parser<'_>, recovery_set: TokenSet) -> Option<CompletedMarker> {
     let m = match p.current() {

crates/parser/src/grammar/types.rs

@@ -20,10 +20,15 @@ pub(super) const TYPE_FIRST: TokenSet = paths::PATH_FIRST.union(TokenSet::new(&[
 
 pub(super) const TYPE_RECOVERY_SET: TokenSet = TokenSet::new(&[
     T![')'],
+    // test_err type_in_array_recover
+    // const _: [&];
+    T![']'],
+    T!['}'],
     T![>],
     T![,],
     // test_err struct_field_recover
     // struct S { f pub g: () }
+    // struct S { f: pub g: () }
     T![pub],
 ]);
 

crates/parser/test_data/generated/runner.rs

@@ -870,6 +870,10 @@ mod err {
         run_and_expect_errors("test_data/parser/inline/err/tuple_pat_leading_comma.rs");
     }
     #[test]
+    fn type_in_array_recover() {
+        run_and_expect_errors("test_data/parser/inline/err/type_in_array_recover.rs");
+    }
+    #[test]
     fn unsafe_block_in_mod() {
         run_and_expect_errors("test_data/parser/inline/err/unsafe_block_in_mod.rs");
     }

crates/parser/test_data/parser/err/0022_bad_exprs.rast

@@ -35,8 +35,8 @@ SOURCE_FILE
         WHITESPACE " "
         LET_STMT
           LET_KW "let"
-          ERROR
-            R_BRACK "]"
+        ERROR
+          R_BRACK "]"
         WHITESPACE " "
         R_CURLY "}"
   WHITESPACE "\n"
@@ -149,7 +149,8 @@ error 17: expected expression, item or let statement
 error 25: expected a name
 error 26: expected `;`, `{`, or `(`
 error 30: expected pattern
-error 31: expected SEMICOLON
+error 30: expected SEMICOLON
+error 30: expected expression, item or let statement
 error 53: expected expression
 error 54: expected R_PAREN
 error 54: expected SEMICOLON

crates/parser/test_data/parser/inline/err/comma_after_default_values_syntax.rast

@@ -23,8 +23,7 @@ SOURCE_FILE
               L_CURLY "{"
               WHITESPACE " "
               DOT2 ".."
-              ERROR
-                COMMA ","
+              COMMA ","
               WHITESPACE " "
               R_CURLY "}"
           SEMICOLON ";"
@@ -39,8 +38,7 @@ SOURCE_FILE
             L_CURLY "{"
             WHITESPACE " "
             DOT2 ".."
-            ERROR
-              COMMA ","
+            COMMA ","
             WHITESPACE " "
             RECORD_EXPR_FIELD
               NAME_REF
@@ -55,5 +53,6 @@ SOURCE_FILE
         R_CURLY "}"
   WHITESPACE "\n"
 error 21: expected expression
+error 21: cannot use a comma after the base struct
 error 36: expected expression
-error 37: expected COMMA
+error 36: cannot use a comma after the base struct

crates/parser/test_data/parser/inline/err/struct_field_recover.rast

@@ -26,6 +26,36 @@ SOURCE_FILE
       WHITESPACE " "
       R_CURLY "}"
   WHITESPACE "\n"
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    WHITESPACE " "
+    RECORD_FIELD_LIST
+      L_CURLY "{"
+      WHITESPACE " "
+      RECORD_FIELD
+        NAME
+          IDENT "f"
+        COLON ":"
+      WHITESPACE " "
+      RECORD_FIELD
+        VISIBILITY
+          PUB_KW "pub"
+        WHITESPACE " "
+        NAME
+          IDENT "g"
+        COLON ":"
+        WHITESPACE " "
+        TUPLE_TYPE
+          L_PAREN "("
+          R_PAREN ")"
+      WHITESPACE " "
+      R_CURLY "}"
+  WHITESPACE "\n"
 error 12: expected COLON
 error 12: expected type
 error 12: expected COMMA
+error 38: expected type
+error 38: expected COMMA

crates/parser/test_data/parser/inline/err/struct_field_recover.rs

@@ -1 +1,2 @@
 struct S { f pub g: () }
+struct S { f: pub g: () }

crates/parser/test_data/parser/inline/err/type_in_array_recover.rast

@@ -0,0 +1,15 @@
+SOURCE_FILE
+  CONST
+    CONST_KW "const"
+    WHITESPACE " "
+    UNDERSCORE "_"
+    COLON ":"
+    WHITESPACE " "
+    SLICE_TYPE
+      L_BRACK "["
+      REF_TYPE
+        AMP "&"
+      R_BRACK "]"
+    SEMICOLON ";"
+  WHITESPACE "\n"
+error 11: expected type

crates/parser/test_data/parser/inline/err/type_in_array_recover.rs

@@ -0,0 +1 @@
+const _: [&];