Merge #11120

11120: internal: move parser tests to parser crate r=matklad a=matklad

bors r+
🤖

Co-authored-by: Aleksey Kladov <aleksey.kladov@gmail.com>

Cargo.lock

@@ -1082,6 +1082,7 @@ dependencies = [
  "expect-test",
  "limit",
  "rustc-ap-rustc_lexer",
+ "sourcegen",
 ]
 
 [[package]]

crates/parser/Cargo.toml

@@ -16,3 +16,5 @@ limit = { path = "../limit", version = "0.0.0" }
 
 [dev-dependencies]
 expect-test = "1.2"
+sourcegen = { path = "../sourcegen" }
+

crates/parser/src/grammar/expressions.rs

@@ -463,13 +463,6 @@ fn method_call_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
 //     x.0.bar;
 //     x.0();
 // }
-
-// test_err bad_tuple_index_expr
-// fn foo() {
-//     x.0.;
-//     x.1i32;
-//     x.0x01;
-// }
 fn field_expr(p: &mut Parser, lhs: CompletedMarker) -> CompletedMarker {
     assert!(p.at(T![.]));
     let m = lhs.precede(p);

crates/parser/src/tests.rs

@@ -1,3 +1,5 @@
+mod sourcegen_inline_tests;
+
 use std::{
     fmt::Write,
     fs,
@@ -9,7 +11,7 @@ use expect_test::expect_file;
 use crate::LexedStr;
 
 #[test]
-fn valid_lexes_input() {
+fn lex_ok() {
     for case in TestCase::list("lexer/ok") {
         let actual = lex(&case.text);
         expect_file![case.txt].assert_eq(&actual)
@@ -17,7 +19,7 @@ fn valid_lexes_input() {
 }
 
 #[test]
-fn invalid_lexes_input() {
+fn lex_err() {
     for case in TestCase::list("lexer/err") {
         let actual = lex(&case.text);
         expect_file![case.txt].assert_eq(&actual)
@@ -39,6 +41,79 @@ fn lex(text: &str) -> String {
     res
 }
 
+#[test]
+fn parse_ok() {
+    for case in TestCase::list("parser/ok") {
+        let (actual, errors) = parse(&case.text);
+        assert!(!errors, "errors in an OK file {}:\n{}", case.rs.display(), actual);
+        expect_file![case.txt].assert_eq(&actual);
+    }
+}
+
+#[test]
+fn parse_inline_ok() {
+    for case in TestCase::list("parser/inline/ok") {
+        let (actual, errors) = parse(&case.text);
+        assert!(!errors, "errors in an OK file {}:\n{}", case.rs.display(), actual);
+        expect_file![case.txt].assert_eq(&actual);
+    }
+}
+
+#[test]
+fn parse_err() {
+    for case in TestCase::list("parser/err") {
+        let (actual, errors) = parse(&case.text);
+        assert!(errors, "no errors in an ERR file {}:\n{}", case.rs.display(), actual);
+        expect_file![case.txt].assert_eq(&actual)
+    }
+}
+
+#[test]
+fn parse_inline_err() {
+    for case in TestCase::list("parser/inline/err") {
+        let (actual, errors) = parse(&case.text);
+        assert!(errors, "no errors in an ERR file {}:\n{}", case.rs.display(), actual);
+        expect_file![case.txt].assert_eq(&actual)
+    }
+}
+
+fn parse(text: &str) -> (String, bool) {
+    let lexed = LexedStr::new(text);
+    let input = lexed.to_input();
+    let output = crate::parse_source_file(&input);
+
+    let mut buf = String::new();
+    let mut errors = Vec::new();
+    let mut indent = String::new();
+    lexed.intersperse_trivia(&output, false, &mut |step| match step {
+        crate::StrStep::Token { kind, text } => {
+            write!(buf, "{}", indent).unwrap();
+            write!(buf, "{:?} {:?}\n", kind, text).unwrap();
+        }
+        crate::StrStep::Enter { kind } => {
+            write!(buf, "{}", indent).unwrap();
+            write!(buf, "{:?}\n", kind).unwrap();
+            indent.push_str("  ");
+        }
+        crate::StrStep::Exit => {
+            indent.pop();
+            indent.pop();
+        }
+        crate::StrStep::Error { msg, pos } => errors.push(format!("error {}: {}\n", pos, msg)),
+    });
+
+    for (token, msg) in lexed.errors() {
+        let pos = lexed.text_start(token);
+        errors.push(format!("error {}: {}\n", pos, msg));
+    }
+
+    let has_errors = !errors.is_empty();
+    for e in errors {
+        buf.push_str(&e);
+    }
+    (buf, has_errors)
+}
+
 #[derive(PartialEq, Eq, PartialOrd, Ord)]
 struct TestCase {
     rs: PathBuf,

crates/parser/src/tests/sourcegen_inline_tests.rs

@@ -0,0 +1,123 @@
+//! This module greps parser's code for specially formatted comments and turns
+//! them into tests.
+
+use std::{
+    collections::HashMap,
+    fs, iter,
+    path::{Path, PathBuf},
+};
+
+#[test]
+fn sourcegen_parser_tests() {
+    let grammar_dir = sourcegen::project_root().join(Path::new("crates/parser/src/grammar"));
+    let tests = tests_from_dir(&grammar_dir);
+
+    install_tests(&tests.ok, "crates/parser/test_data/parser/inline/ok");
+    install_tests(&tests.err, "crates/parser/test_data/parser/inline/err");
+
+    fn install_tests(tests: &HashMap<String, Test>, into: &str) {
+        let tests_dir = sourcegen::project_root().join(into);
+        if !tests_dir.is_dir() {
+            fs::create_dir_all(&tests_dir).unwrap();
+        }
+        // ok is never actually read, but it needs to be specified to create a Test in existing_tests
+        let existing = existing_tests(&tests_dir, true);
+        for t in existing.keys().filter(|&t| !tests.contains_key(t)) {
+            panic!("Test is deleted: {}", t);
+        }
+
+        let mut new_idx = existing.len() + 1;
+        for (name, test) in tests {
+            let path = match existing.get(name) {
+                Some((path, _test)) => path.clone(),
+                None => {
+                    let file_name = format!("{:04}_{}.rs", new_idx, name);
+                    new_idx += 1;
+                    tests_dir.join(file_name)
+                }
+            };
+            sourcegen::ensure_file_contents(&path, &test.text);
+        }
+    }
+}
+
+#[derive(Debug)]
+struct Test {
+    name: String,
+    text: String,
+    ok: bool,
+}
+
+#[derive(Default, Debug)]
+struct Tests {
+    ok: HashMap<String, Test>,
+    err: HashMap<String, Test>,
+}
+
+fn collect_tests(s: &str) -> Vec<Test> {
+    let mut res = Vec::new();
+    for comment_block in sourcegen::CommentBlock::extract_untagged(s) {
+        let first_line = &comment_block.contents[0];
+        let (name, ok) = if let Some(name) = first_line.strip_prefix("test ") {
+            (name.to_string(), true)
+        } else if let Some(name) = first_line.strip_prefix("test_err ") {
+            (name.to_string(), false)
+        } else {
+            continue;
+        };
+        let text: String = comment_block.contents[1..]
+            .iter()
+            .cloned()
+            .chain(iter::once(String::new()))
+            .collect::<Vec<_>>()
+            .join("\n");
+        assert!(!text.trim().is_empty() && text.ends_with('\n'));
+        res.push(Test { name, text, ok })
+    }
+    res
+}
+
+fn tests_from_dir(dir: &Path) -> Tests {
+    let mut res = Tests::default();
+    for entry in sourcegen::list_rust_files(dir) {
+        process_file(&mut res, entry.as_path());
+    }
+    let grammar_rs = dir.parent().unwrap().join("grammar.rs");
+    process_file(&mut res, &grammar_rs);
+    return res;
+
+    fn process_file(res: &mut Tests, path: &Path) {
+        let text = fs::read_to_string(path).unwrap();
+
+        for test in collect_tests(&text) {
+            if test.ok {
+                if let Some(old_test) = res.ok.insert(test.name.clone(), test) {
+                    panic!("Duplicate test: {}", old_test.name);
+                }
+            } else if let Some(old_test) = res.err.insert(test.name.clone(), test) {
+                panic!("Duplicate test: {}", old_test.name);
+            }
+        }
+    }
+}
+
+fn existing_tests(dir: &Path, ok: bool) -> HashMap<String, (PathBuf, Test)> {
+    let mut res = HashMap::default();
+    for file in fs::read_dir(dir).unwrap() {
+        let file = file.unwrap();
+        let path = file.path();
+        if path.extension().unwrap_or_default() != "rs" {
+            continue;
+        }
+        let name = {
+            let file_name = path.file_name().unwrap().to_str().unwrap();
+            file_name[5..file_name.len() - 3].to_string()
+        };
+        let text = fs::read_to_string(&path).unwrap();
+        let test = Test { name: name.clone(), text, ok };
+        if let Some(old) = res.insert(name, (path, test)) {
+            println!("Duplicate test: {:?}", old);
+        }
+    }
+    res
+}

crates/parser/test_data/parser/err/0000_struct_field_missing_comma.txt

@@ -0,0 +1,34 @@
+SOURCE_FILE
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    WHITESPACE " "
+    RECORD_FIELD_LIST
+      L_CURLY "{"
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        NAME
+          IDENT "a"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "u32"
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        NAME
+          IDENT "b"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "u32"
+      WHITESPACE "\n"
+      R_CURLY "}"
+error 21: expected COMMA

crates/parser/test_data/parser/err/0001_item_recovery_in_file.txt

@@ -0,0 +1,18 @@
+SOURCE_FILE
+  ERROR
+    IF_KW "if"
+  WHITESPACE " "
+  ERROR
+    MATCH_KW "match"
+  WHITESPACE "\n\n"
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    WHITESPACE " "
+    RECORD_FIELD_LIST
+      L_CURLY "{"
+      R_CURLY "}"
+error 0: expected an item
+error 3: expected an item

crates/parser/test_data/parser/err/0002_duplicate_shebang.txt

@@ -0,0 +1,45 @@
+SOURCE_FILE
+  SHEBANG "#!/use/bin/env rusti"
+  WHITESPACE "\n"
+  ATTR
+    POUND "#"
+    BANG "!"
+  ERROR
+    SLASH "/"
+  USE
+    USE_KW "use"
+    ERROR
+      SLASH "/"
+  MACRO_CALL
+    PATH
+      PATH_SEGMENT
+        NAME_REF
+          IDENT "bin"
+  ERROR
+    SLASH "/"
+  MACRO_CALL
+    PATH
+      PATH_SEGMENT
+        NAME_REF
+          IDENT "env"
+  WHITESPACE " "
+  MACRO_CALL
+    PATH
+      PATH_SEGMENT
+        NAME_REF
+          IDENT "rusti"
+  WHITESPACE "\n"
+error 23: expected `[`
+error 23: expected an item
+error 27: expected one of `*`, `::`, `{`, `self`, `super` or an identifier
+error 28: expected SEMICOLON
+error 31: expected BANG
+error 31: expected `{`, `[`, `(`
+error 31: expected SEMICOLON
+error 31: expected an item
+error 35: expected BANG
+error 35: expected `{`, `[`, `(`
+error 35: expected SEMICOLON
+error 41: expected BANG
+error 41: expected `{`, `[`, `(`
+error 41: expected SEMICOLON

crates/parser/test_data/parser/err/0003_C++_semicolon.txt

@@ -0,0 +1,39 @@
+SOURCE_FILE
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    WHITESPACE " "
+    RECORD_FIELD_LIST
+      L_CURLY "{"
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        NAME
+          IDENT "a"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "i32"
+      COMMA ","
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        NAME
+          IDENT "b"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "String"
+      COMMA ","
+      WHITESPACE "\n"
+      R_CURLY "}"
+  ERROR
+    SEMICOLON ";"
+error 39: expected item, found `;`
+consider removing this semicolon

crates/parser/test_data/parser/err/0004_use_path_bad_segment.txt

@@ -0,0 +1,15 @@
+SOURCE_FILE
+  USE
+    USE_KW "use"
+    WHITESPACE " "
+    USE_TREE
+      PATH
+        PATH
+          PATH_SEGMENT
+            NAME_REF
+              IDENT "foo"
+        COLON2 "::"
+        ERROR
+          INT_NUMBER "92"
+    SEMICOLON ";"
+error 9: expected identifier

crates/parser/test_data/parser/err/0005_attribute_recover.txt

@@ -0,0 +1,62 @@
+SOURCE_FILE
+  FN
+    ATTR
+      POUND "#"
+      L_BRACK "["
+      META
+        PATH
+          PATH_SEGMENT
+            NAME_REF
+              IDENT "foo"
+        TOKEN_TREE
+          L_PAREN "("
+          IDENT "foo"
+          COMMA ","
+          WHITESPACE " "
+          PLUS "+"
+          COMMA ","
+          WHITESPACE " "
+          INT_NUMBER "92"
+          R_PAREN ")"
+      R_BRACK "]"
+    WHITESPACE "\n"
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n\n\n"
+  ATTR
+    POUND "#"
+    L_BRACK "["
+    META
+      PATH
+        PATH_SEGMENT
+          NAME_REF
+            IDENT "foo"
+      TOKEN_TREE
+        L_PAREN "("
+        WHITESPACE "\n"
+        FN_KW "fn"
+        WHITESPACE " "
+        IDENT "foo"
+        TOKEN_TREE
+          L_PAREN "("
+          R_PAREN ")"
+        WHITESPACE " "
+        TOKEN_TREE
+          L_CURLY "{"
+          WHITESPACE "\n"
+          R_CURLY "}"
+  WHITESPACE "\n"
+error 53: expected R_PAREN
+error 53: expected `]`
+error 53: expected an item

crates/parser/test_data/parser/err/0006_named_field_recovery.txt

@@ -0,0 +1,74 @@
+SOURCE_FILE
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    WHITESPACE " "
+    RECORD_FIELD_LIST
+      L_CURLY "{"
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        NAME
+          IDENT "f"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "u32"
+      COMMA ","
+      WHITESPACE "\n    "
+      VISIBILITY
+        PUB_KW "pub"
+      WHITESPACE " "
+      ERROR
+        INT_NUMBER "92"
+      WHITESPACE "\n    "
+      ERROR
+        PLUS "+"
+      WHITESPACE " "
+      ERROR
+        MINUS "-"
+      WHITESPACE " "
+      ERROR
+        STAR "*"
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        VISIBILITY
+          PUB_KW "pub"
+        WHITESPACE " "
+        NAME
+          IDENT "x"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "u32"
+      COMMA ","
+      WHITESPACE "\n    "
+      RECORD_FIELD
+        NAME
+          IDENT "z"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "f64"
+      COMMA ","
+      WHITESPACE "\n"
+      R_CURLY "}"
+  WHITESPACE "\n"
+error 31: expected field declaration
+error 33: expected COMMA
+error 38: expected field declaration
+error 39: expected COMMA
+error 40: expected field declaration
+error 41: expected COMMA
+error 42: expected field declaration
+error 43: expected COMMA

crates/parser/test_data/parser/err/0007_stray_curly_in_file.txt

@@ -0,0 +1,33 @@
+SOURCE_FILE
+  ERROR
+    R_CURLY "}"
+  WHITESPACE "\n\n"
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    SEMICOLON ";"
+  WHITESPACE "\n\n"
+  ERROR
+    R_CURLY "}"
+  WHITESPACE "\n\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n\n"
+  ERROR
+    R_CURLY "}"
+  WHITESPACE "\n"
+error 0: unmatched `}`
+error 14: unmatched `}`
+error 29: unmatched `}`

crates/parser/test_data/parser/err/0008_item_block_recovery.txt

@@ -0,0 +1,81 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n\n"
+  MACRO_CALL
+    PATH
+      PATH_SEGMENT
+        NAME_REF
+          IDENT "bar"
+    TOKEN_TREE
+      L_PAREN "("
+      R_PAREN ")"
+  WHITESPACE " "
+  ERROR
+    L_CURLY "{"
+    WHITESPACE "\n    "
+    IF_EXPR
+      IF_KW "if"
+      WHITESPACE " "
+      CONDITION
+        LITERAL
+          TRUE_KW "true"
+      WHITESPACE " "
+      BLOCK_EXPR
+        STMT_LIST
+          L_CURLY "{"
+          WHITESPACE "\n        "
+          LITERAL
+            INT_NUMBER "1"
+          WHITESPACE "\n    "
+          R_CURLY "}"
+      WHITESPACE " "
+      ELSE_KW "else"
+      WHITESPACE " "
+      BLOCK_EXPR
+        STMT_LIST
+          L_CURLY "{"
+          WHITESPACE "\n        "
+          BIN_EXPR
+            LITERAL
+              INT_NUMBER "2"
+            WHITESPACE " "
+            PLUS "+"
+            WHITESPACE " "
+            LITERAL
+              INT_NUMBER "3"
+          WHITESPACE "\n    "
+          R_CURLY "}"
+    WHITESPACE "\n"
+    R_CURLY "}"
+  WHITESPACE "\n\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "baz"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 17: expected BANG
+error 19: expected SEMICOLON
+error 20: expected an item

crates/parser/test_data/parser/err/0009_broken_struct_type_parameter.txt

@@ -0,0 +1,56 @@
+SOURCE_FILE
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "S"
+    GENERIC_PARAM_LIST
+      L_ANGLE "<"
+      ERROR
+        INT_NUMBER "90"
+  WHITESPACE " "
+  ERROR
+    PLUS "+"
+  WHITESPACE " "
+  ERROR
+    INT_NUMBER "2"
+  ERROR
+    R_ANGLE ">"
+  WHITESPACE " "
+  ERROR
+    L_CURLY "{"
+    WHITESPACE "\n    "
+    EXPR_STMT
+      PATH_EXPR
+        PATH
+          PATH_SEGMENT
+            NAME_REF
+              IDENT "f"
+    ERROR
+      COLON ":"
+    WHITESPACE " "
+    PATH_EXPR
+      PATH
+        PATH_SEGMENT
+          NAME_REF
+            IDENT "u32"
+    WHITESPACE "\n"
+    R_CURLY "}"
+  WHITESPACE "\n\n"
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "T"
+    SEMICOLON ";"
+  WHITESPACE "\n"
+error 9: expected type parameter
+error 11: expected COMMA
+error 11: expected R_ANGLE
+error 11: expected `;`, `{`, or `(`
+error 12: expected an item
+error 14: expected an item
+error 15: expected an item
+error 17: expected an item
+error 24: expected SEMICOLON
+error 24: expected expression

crates/parser/test_data/parser/err/0010_unsafe_lambda_block.txt

@@ -0,0 +1,45 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        EXPR_STMT
+          CLOSURE_EXPR
+            PARAM_LIST
+              PIPE "|"
+              PIPE "|"
+            WHITESPACE " "
+            RET_TYPE
+              THIN_ARROW "->"
+              WHITESPACE " "
+              TUPLE_TYPE
+                L_PAREN "("
+                R_PAREN ")"
+        WHITESPACE " "
+        EXPR_STMT
+          BLOCK_EXPR
+            UNSAFE_KW "unsafe"
+            WHITESPACE " "
+            STMT_LIST
+              L_CURLY "{"
+              WHITESPACE " "
+              TUPLE_EXPR
+                L_PAREN "("
+                R_PAREN ")"
+              WHITESPACE " "
+              R_CURLY "}"
+          SEMICOLON ";"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 24: expected a block
+error 24: expected SEMICOLON

crates/parser/test_data/parser/err/0011_extern_struct.txt

@@ -0,0 +1,13 @@
+SOURCE_FILE
+  ERROR
+    ABI
+      EXTERN_KW "extern"
+  WHITESPACE " "
+  STRUCT
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "Foo"
+    SEMICOLON ";"
+  WHITESPACE "\n"
+error 6: expected existential, fn, trait or impl

crates/parser/test_data/parser/err/0013_invalid_type.txt

@@ -0,0 +1,89 @@
+SOURCE_FILE
+  STRUCT
+    VISIBILITY
+      PUB_KW "pub"
+    WHITESPACE " "
+    STRUCT_KW "struct"
+    WHITESPACE " "
+    NAME
+      IDENT "Cache"
+    TUPLE_FIELD_LIST
+      L_PAREN "("
+      WHITESPACE "\n    "
+      TUPLE_FIELD
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "RefCell"
+              GENERIC_ARG_LIST
+                L_ANGLE "<"
+                TYPE_ARG
+                  PATH_TYPE
+                    PATH
+                      PATH_SEGMENT
+                        NAME_REF
+                          IDENT "HashMap"
+                        GENERIC_ARG_LIST
+                          L_ANGLE "<"
+                          WHITESPACE "\n        "
+                          TYPE_ARG
+                            PATH_TYPE
+                              PATH
+                                PATH_SEGMENT
+                                  NAME_REF
+                                    IDENT "TypeId"
+                          COMMA ","
+                          WHITESPACE "\n        "
+                          TYPE_ARG
+                            PATH_TYPE
+                              PATH
+                                PATH_SEGMENT
+                                  NAME_REF
+                                    IDENT "Box"
+                                  GENERIC_ARG_LIST
+                                    L_ANGLE "<"
+                                    TYPE_ARG
+                                      ERROR
+                                        AT "@"
+      WHITESPACE " "
+      TUPLE_FIELD
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "Any"
+      ERROR
+  ERROR
+    R_ANGLE ">"
+  ERROR
+    COMMA ","
+  WHITESPACE "\n    "
+  ERROR
+    R_ANGLE ">"
+  ERROR
+    R_ANGLE ">"
+  WHITESPACE "\n"
+  ERROR
+    R_PAREN ")"
+  ERROR
+    SEMICOLON ";"
+  WHITESPACE "\n\n"
+error 67: expected type
+error 68: expected COMMA
+error 68: expected R_ANGLE
+error 68: expected COMMA
+error 68: expected R_ANGLE
+error 68: expected COMMA
+error 68: expected R_ANGLE
+error 68: expected COMMA
+error 72: expected COMMA
+error 72: expected a type
+error 72: expected R_PAREN
+error 72: expected SEMICOLON
+error 72: expected an item
+error 73: expected an item
+error 79: expected an item
+error 80: expected an item
+error 82: expected an item
+error 83: expected an item

crates/parser/test_data/parser/err/0014_where_no_bounds.txt

@@ -0,0 +1,32 @@
+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 " "
+    WHERE_CLAUSE
+      WHERE_KW "where"
+      WHITESPACE " "
+      WHERE_PRED
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "T"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 19: expected colon

crates/parser/test_data/parser/err/0015_curly_in_params.txt

@@ -0,0 +1,24 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+  ERROR
+    R_CURLY "}"
+  ERROR
+    R_PAREN ")"
+  WHITESPACE " "
+  ERROR
+    L_CURLY "{"
+    WHITESPACE "\n"
+    R_CURLY "}"
+  WHITESPACE "\n"
+error 7: expected value parameter
+error 7: expected R_PAREN
+error 7: expected a block
+error 7: unmatched `}`
+error 8: expected an item
+error 10: expected an item

crates/parser/test_data/parser/err/0016_missing_semi.txt

@@ -0,0 +1,44 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        EXPR_STMT
+          CALL_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "foo"
+            ARG_LIST
+              L_PAREN "("
+              WHITESPACE "\n        "
+              LITERAL
+                INT_NUMBER "1"
+              COMMA ","
+              WHITESPACE " "
+              LITERAL
+                INT_NUMBER "2"
+              WHITESPACE "\n    "
+              R_PAREN ")"
+        WHITESPACE "\n    "
+        EXPR_STMT
+          RETURN_EXPR
+            RETURN_KW "return"
+            WHITESPACE " "
+            LITERAL
+              INT_NUMBER "92"
+          SEMICOLON ";"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 38: expected SEMICOLON

crates/parser/test_data/parser/err/0017_incomplete_binexpr.txt

@@ -0,0 +1,47 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      PARAM
+        IDENT_PAT
+          NAME
+            IDENT "foo"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "i32"
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "bar"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "92"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        BIN_EXPR
+          LITERAL
+            INT_NUMBER "1"
+          WHITESPACE " "
+          PLUS "+"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 44: expected expression

crates/parser/test_data/parser/err/0018_incomplete_fn.txt

@@ -0,0 +1,133 @@
+SOURCE_FILE
+  IMPL
+    IMPL_KW "impl"
+    WHITESPACE " "
+    PATH_TYPE
+      PATH
+        PATH_SEGMENT
+          NAME_REF
+            IDENT "FnScopes"
+    WHITESPACE " "
+    ASSOC_ITEM_LIST
+      L_CURLY "{"
+      WHITESPACE "\n    "
+      FN
+        FN_KW "fn"
+        WHITESPACE " "
+        NAME
+          IDENT "new_scope"
+        PARAM_LIST
+          L_PAREN "("
+          PARAM
+            REF_PAT
+              AMP "&"
+          R_PAREN ")"
+        WHITESPACE " "
+        RET_TYPE
+          THIN_ARROW "->"
+          WHITESPACE " "
+          PATH_TYPE
+            PATH
+              PATH_SEGMENT
+                NAME_REF
+                  IDENT "ScopeId"
+        WHITESPACE " "
+        BLOCK_EXPR
+          STMT_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            LET_STMT
+              LET_KW "let"
+              WHITESPACE " "
+              IDENT_PAT
+                NAME
+                  IDENT "res"
+              WHITESPACE " "
+              EQ "="
+              WHITESPACE " "
+              METHOD_CALL_EXPR
+                FIELD_EXPR
+                  PATH_EXPR
+                    PATH
+                      PATH_SEGMENT
+                        NAME_REF
+                          SELF_KW "self"
+                  DOT "."
+                  NAME_REF
+                    IDENT "scopes"
+                DOT "."
+                NAME_REF
+                  IDENT "len"
+                ARG_LIST
+                  L_PAREN "("
+                  R_PAREN ")"
+              SEMICOLON ";"
+            WHITESPACE "\n        "
+            METHOD_CALL_EXPR
+              FIELD_EXPR
+                PATH_EXPR
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        SELF_KW "self"
+                DOT "."
+                NAME_REF
+                  IDENT "scopes"
+              DOT "."
+              NAME_REF
+                IDENT "push"
+              ARG_LIST
+                L_PAREN "("
+                RECORD_EXPR
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "ScopeData"
+                  WHITESPACE " "
+                  RECORD_EXPR_FIELD_LIST
+                    L_CURLY "{"
+                    WHITESPACE " "
+                    RECORD_EXPR_FIELD
+                      NAME_REF
+                        IDENT "parent"
+                      COLON ":"
+                      WHITESPACE " "
+                      PATH_EXPR
+                        PATH
+                          PATH_SEGMENT
+                            NAME_REF
+                              IDENT "None"
+                    COMMA ","
+                    WHITESPACE " "
+                    RECORD_EXPR_FIELD
+                      NAME_REF
+                        IDENT "entries"
+                      COLON ":"
+                      WHITESPACE " "
+                      MACRO_CALL
+                        PATH
+                          PATH_SEGMENT
+                            NAME_REF
+                              IDENT "vec"
+                        BANG "!"
+                        TOKEN_TREE
+                          L_BRACK "["
+                          R_BRACK "]"
+                    WHITESPACE " "
+                    R_CURLY "}"
+                R_PAREN ")"
+            WHITESPACE "\n    "
+            R_CURLY "}"
+      WHITESPACE "\n\n    "
+      FN
+        FN_KW "fn"
+        WHITESPACE " "
+        NAME
+          IDENT "set_parent"
+      WHITESPACE "\n"
+      R_CURLY "}"
+  WHITESPACE "\n"
+error 34: expected pattern
+error 34: missing type for function parameter
+error 180: expected function arguments
+error 180: expected a block

crates/parser/test_data/parser/err/0019_let_recover.txt

@@ -0,0 +1,107 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "foo"
+          WHITESPACE " "
+          EQ "="
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "bar"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "1"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "baz"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "92"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+        WHITESPACE "\n    "
+        EXPR_STMT
+          IF_EXPR
+            IF_KW "if"
+            WHITESPACE " "
+            CONDITION
+              LITERAL
+                TRUE_KW "true"
+            WHITESPACE " "
+            BLOCK_EXPR
+              STMT_LIST
+                L_CURLY "{"
+                R_CURLY "}"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+        WHITESPACE "\n    "
+        EXPR_STMT
+          WHILE_EXPR
+            WHILE_KW "while"
+            WHITESPACE " "
+            CONDITION
+              LITERAL
+                TRUE_KW "true"
+            WHITESPACE " "
+            BLOCK_EXPR
+              STMT_LIST
+                L_CURLY "{"
+                R_CURLY "}"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+        WHITESPACE "\n    "
+        LOOP_EXPR
+          LOOP_KW "loop"
+          WHITESPACE " "
+          BLOCK_EXPR
+            STMT_LIST
+              L_CURLY "{"
+              R_CURLY "}"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 24: expected expression
+error 24: expected SEMICOLON
+error 49: expected pattern
+error 49: expected SEMICOLON
+error 75: expected pattern
+error 75: expected SEMICOLON
+error 98: expected pattern
+error 98: expected SEMICOLON
+error 124: expected pattern
+error 124: expected SEMICOLON

crates/parser/test_data/parser/err/0020_fn_recover.txt

@@ -0,0 +1,21 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+  WHITESPACE "\n\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 2: expected a name
+error 2: expected function arguments
+error 2: expected a block

crates/parser/test_data/parser/err/0021_incomplete_param.txt

@@ -0,0 +1,34 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      PARAM
+        IDENT_PAT
+          NAME
+            IDENT "x"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "i32"
+      COMMA ","
+      WHITESPACE " "
+      PARAM
+        IDENT_PAT
+          NAME
+            IDENT "y"
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 16: missing type for function parameter

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

@@ -0,0 +1,171 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "a"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE " "
+        EXPR_STMT
+          ARRAY_EXPR
+            L_BRACK "["
+            LITERAL
+              INT_NUMBER "1"
+            COMMA ","
+            WHITESPACE " "
+            LITERAL
+              INT_NUMBER "2"
+            COMMA ","
+            WHITESPACE " "
+            ERROR
+              AT "@"
+        ERROR
+          COMMA ","
+        WHITESPACE " "
+        STRUCT
+          STRUCT_KW "struct"
+          ERROR
+            COMMA ","
+        WHITESPACE " "
+        LET_STMT
+          LET_KW "let"
+          ERROR
+            R_BRACK "]"
+        WHITESPACE " "
+        R_CURLY "}"
+  WHITESPACE "\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "b"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE " "
+        EXPR_STMT
+          CALL_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "foo"
+            ARG_LIST
+              L_PAREN "("
+              LITERAL
+                INT_NUMBER "1"
+              COMMA ","
+              WHITESPACE " "
+              LITERAL
+                INT_NUMBER "2"
+              COMMA ","
+              WHITESPACE " "
+              ERROR
+                AT "@"
+        ERROR
+          COMMA ","
+        WHITESPACE " "
+        IMPL
+          IMPL_KW "impl"
+        ERROR
+          COMMA ","
+        WHITESPACE " "
+        LET_STMT
+          LET_KW "let"
+        ERROR
+          R_PAREN ")"
+        WHITESPACE " "
+        R_CURLY "}"
+  WHITESPACE "\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "c"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE " "
+        EXPR_STMT
+          METHOD_CALL_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "foo"
+            DOT "."
+            NAME_REF
+              IDENT "bar"
+            ARG_LIST
+              L_PAREN "("
+              LITERAL
+                INT_NUMBER "1"
+              COMMA ","
+              WHITESPACE " "
+              LITERAL
+                INT_NUMBER "2"
+              COMMA ","
+              WHITESPACE " "
+              ERROR
+                AT "@"
+        ERROR
+          COMMA ","
+        WHITESPACE " "
+        ERROR
+          R_BRACK "]"
+        ERROR
+          COMMA ","
+        WHITESPACE " "
+        TRAIT
+          TRAIT_KW "trait"
+          ERROR
+            COMMA ","
+        WHITESPACE " "
+        LET_STMT
+          LET_KW "let"
+        ERROR
+          R_PAREN ")"
+        WHITESPACE " "
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 16: expected expression
+error 17: expected R_BRACK
+error 17: expected SEMICOLON
+error 17: expected expression
+error 25: expected a name
+error 26: expected `;`, `{`, or `(`
+error 30: expected pattern
+error 31: expected SEMICOLON
+error 53: expected expression
+error 54: expected SEMICOLON
+error 54: expected expression
+error 60: expected type
+error 60: expected `{`
+error 60: expected expression
+error 65: expected pattern
+error 65: expected SEMICOLON
+error 65: expected expression
+error 92: expected expression
+error 93: expected SEMICOLON
+error 93: expected expression
+error 95: expected expression
+error 96: expected expression
+error 103: expected a name
+error 104: expected `{`
+error 108: expected pattern
+error 108: expected SEMICOLON
+error 108: expected expression

crates/parser/test_data/parser/err/0023_mismatched_paren.txt

@@ -0,0 +1,44 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        MACRO_CALL
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "foo"
+          BANG "!"
+          WHITESPACE " "
+          TOKEN_TREE
+            L_PAREN "("
+            WHITESPACE "\n        "
+            IDENT "bar"
+            COMMA ","
+            WHITESPACE " "
+            STRING "\"baz\""
+            COMMA ","
+            WHITESPACE " "
+            INT_NUMBER "1"
+            COMMA ","
+            WHITESPACE " "
+            FLOAT_NUMBER "2.0"
+        WHITESPACE "\n    "
+        R_CURLY "}"
+  WHITESPACE " "
+  COMMENT "//~ ERROR incorrect close delimiter"
+  WHITESPACE "\n"
+  ERROR
+    R_CURLY "}"
+  WHITESPACE "\n"
+error 49: unmatched `}`
+error 92: unmatched `}`

crates/parser/test_data/parser/err/0024_many_type_parens.txt

@@ -0,0 +1,321 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "f"
+    GENERIC_PARAM_LIST
+      L_ANGLE "<"
+      TYPE_PARAM
+        NAME
+          IDENT "T"
+        COLON ":"
+        WHITESPACE " "
+        TYPE_BOUND_LIST
+          TYPE_BOUND
+            L_PAREN "("
+            PATH_TYPE
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "Copy"
+            R_PAREN ")"
+          WHITESPACE " "
+          PLUS "+"
+          WHITESPACE " "
+          TYPE_BOUND
+            L_PAREN "("
+            QUESTION "?"
+            PATH_TYPE
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "Sized"
+            R_PAREN ")"
+          WHITESPACE " "
+          PLUS "+"
+          WHITESPACE " "
+          TYPE_BOUND
+            L_PAREN "("
+            FOR_TYPE
+              FOR_KW "for"
+              GENERIC_PARAM_LIST
+                L_ANGLE "<"
+                LIFETIME_PARAM
+                  LIFETIME
+                    LIFETIME_IDENT "'a"
+                R_ANGLE ">"
+              WHITESPACE " "
+              PATH_TYPE
+                PATH
+                  PATH_SEGMENT
+                    NAME_REF
+                      IDENT "Trait"
+                    GENERIC_ARG_LIST
+                      L_ANGLE "<"
+                      LIFETIME_ARG
+                        LIFETIME
+                          LIFETIME_IDENT "'a"
+                      R_ANGLE ">"
+            R_PAREN ")"
+      R_ANGLE ">"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n\n"
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          WILDCARD_PAT
+            UNDERSCORE "_"
+          COLON ":"
+          WHITESPACE " "
+          DYN_TRAIT_TYPE
+            TYPE_BOUND_LIST
+              TYPE_BOUND
+                PATH_TYPE
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "Box"
+                      GENERIC_ARG_LIST
+                        L_ANGLE "<"
+                        TYPE_ARG
+                          PAREN_TYPE
+                            L_PAREN "("
+                            PATH_TYPE
+                              PATH
+                                PATH_SEGMENT
+                                  NAME_REF
+                                    IDENT "Copy"
+                            R_PAREN ")"
+              WHITESPACE " "
+              PLUS "+"
+              WHITESPACE " "
+              TYPE_BOUND
+                L_PAREN "("
+                QUESTION "?"
+                PATH_TYPE
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "Sized"
+                R_PAREN ")"
+              WHITESPACE " "
+              PLUS "+"
+              WHITESPACE " "
+              TYPE_BOUND
+                L_PAREN "("
+                FOR_TYPE
+                  FOR_KW "for"
+                  GENERIC_PARAM_LIST
+                    L_ANGLE "<"
+                    LIFETIME_PARAM
+                      LIFETIME
+                        LIFETIME_IDENT "'a"
+                    R_ANGLE ">"
+                  WHITESPACE " "
+                  PATH_TYPE
+                    PATH
+                      PATH_SEGMENT
+                        NAME_REF
+                          IDENT "Trait"
+                        GENERIC_ARG_LIST
+                          L_ANGLE "<"
+                          LIFETIME_ARG
+                            LIFETIME
+                              LIFETIME_IDENT "'a"
+                          R_ANGLE ">"
+                R_PAREN ")"
+        ERROR
+          R_ANGLE ">"
+        SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          WILDCARD_PAT
+            UNDERSCORE "_"
+          COLON ":"
+          WHITESPACE " "
+          PATH_TYPE
+            PATH
+              PATH_SEGMENT
+                NAME_REF
+                  IDENT "Box"
+                GENERIC_ARG_LIST
+                  L_ANGLE "<"
+                  TYPE_ARG
+                    PAREN_TYPE
+                      L_PAREN "("
+                      ERROR
+                        QUESTION "?"
+        EXPR_STMT
+          PATH_EXPR
+            PATH
+              PATH_SEGMENT
+                NAME_REF
+                  IDENT "Sized"
+        ERROR
+          R_PAREN ")"
+        WHITESPACE " "
+        ERROR
+          PLUS "+"
+        WHITESPACE " "
+        EXPR_STMT
+          TUPLE_EXPR
+            L_PAREN "("
+            FOR_EXPR
+              FOR_KW "for"
+              PATH_PAT
+                PATH
+                  PATH_SEGMENT
+                    L_ANGLE "<"
+                    ERROR
+                      LIFETIME_IDENT "'a"
+                    R_ANGLE ">"
+              WHITESPACE " "
+              BIN_EXPR
+                BIN_EXPR
+                  BIN_EXPR
+                    BIN_EXPR
+                      PATH_EXPR
+                        PATH
+                          PATH_SEGMENT
+                            NAME_REF
+                              IDENT "Trait"
+                      L_ANGLE "<"
+                      ERROR
+                        LIFETIME_IDENT "'a"
+                    R_ANGLE ">"
+                    ERROR
+                      R_PAREN ")"
+                  WHITESPACE " "
+                  PLUS "+"
+                  WHITESPACE " "
+                  PAREN_EXPR
+                    L_PAREN "("
+                    PATH_EXPR
+                      PATH
+                        PATH_SEGMENT
+                          NAME_REF
+                            IDENT "Copy"
+                    R_PAREN ")"
+                R_ANGLE ">"
+                ERROR
+                  SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          WILDCARD_PAT
+            UNDERSCORE "_"
+          COLON ":"
+          WHITESPACE " "
+          DYN_TRAIT_TYPE
+            TYPE_BOUND_LIST
+              TYPE_BOUND
+                PATH_TYPE
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "Box"
+                      GENERIC_ARG_LIST
+                        L_ANGLE "<"
+                        TYPE_ARG
+                          PAREN_TYPE
+                            L_PAREN "("
+                            FOR_TYPE
+                              FOR_KW "for"
+                              GENERIC_PARAM_LIST
+                                L_ANGLE "<"
+                                LIFETIME_PARAM
+                                  LIFETIME
+                                    LIFETIME_IDENT "'a"
+                                R_ANGLE ">"
+                              WHITESPACE " "
+                              PATH_TYPE
+                                PATH
+                                  PATH_SEGMENT
+                                    NAME_REF
+                                      IDENT "Trait"
+                                    GENERIC_ARG_LIST
+                                      L_ANGLE "<"
+                                      LIFETIME_ARG
+                                        LIFETIME
+                                          LIFETIME_IDENT "'a"
+                                      R_ANGLE ">"
+                            R_PAREN ")"
+              WHITESPACE " "
+              PLUS "+"
+              WHITESPACE " "
+              TYPE_BOUND
+                L_PAREN "("
+                PATH_TYPE
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "Copy"
+                R_PAREN ")"
+              WHITESPACE " "
+              PLUS "+"
+              WHITESPACE " "
+              TYPE_BOUND
+                L_PAREN "("
+                QUESTION "?"
+                PATH_TYPE
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "Sized"
+                R_PAREN ")"
+        ERROR
+          R_ANGLE ">"
+        SEMICOLON ";"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 88: expected COMMA
+error 88: expected R_ANGLE
+error 121: expected SEMICOLON
+error 121: expected expression
+error 140: expected type
+error 141: expected R_PAREN
+error 141: expected COMMA
+error 141: expected R_ANGLE
+error 141: expected SEMICOLON
+error 146: expected SEMICOLON
+error 146: expected expression
+error 148: expected expression
+error 155: expected type
+error 158: expected IN_KW
+error 165: expected expression
+error 168: expected expression
+error 179: expected expression
+error 180: expected a block
+error 180: expected COMMA
+error 180: expected expression
+error 180: expected R_PAREN
+error 180: expected SEMICOLON
+error 215: expected COMMA
+error 215: expected R_ANGLE
+error 235: expected SEMICOLON
+error 235: expected expression

crates/parser/test_data/parser/err/0025_nope.txt

@@ -0,0 +1,204 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        ENUM
+          ENUM_KW "enum"
+          WHITESPACE " "
+          NAME
+            IDENT "Test"
+          WHITESPACE " "
+          VARIANT_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            VARIANT
+              NAME
+                IDENT "Var1"
+            COMMA ","
+            WHITESPACE "\n        "
+            VARIANT
+              NAME
+                IDENT "Var2"
+              TUPLE_FIELD_LIST
+                L_PAREN "("
+                TUPLE_FIELD
+                  PATH_TYPE
+                    PATH
+                      PATH_SEGMENT
+                        NAME_REF
+                          IDENT "String"
+                R_PAREN ")"
+            COMMA ","
+            WHITESPACE "\n        "
+            VARIANT
+              NAME
+                IDENT "Var3"
+              WHITESPACE " "
+              RECORD_FIELD_LIST
+                L_CURLY "{"
+                WHITESPACE "\n            "
+                RECORD_FIELD
+                  NAME
+                    IDENT "abc"
+                  COLON ":"
+                WHITESPACE " "
+                ERROR
+                  L_CURLY "{"
+                  R_CURLY "}"
+                ERROR
+                  COMMA ","
+                WHITESPACE " "
+                COMMENT "//~ ERROR: expected type, found `{`"
+                WHITESPACE "\n        "
+                R_CURLY "}"
+            COMMA ","
+            WHITESPACE "\n    "
+            R_CURLY "}"
+        WHITESPACE "\n\n    "
+        COMMENT "// recover..."
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "a"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "1"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        ENUM
+          ENUM_KW "enum"
+          WHITESPACE " "
+          NAME
+            IDENT "Test2"
+          WHITESPACE " "
+          VARIANT_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            VARIANT
+              NAME
+                IDENT "Fine"
+            COMMA ","
+            WHITESPACE "\n    "
+            R_CURLY "}"
+        WHITESPACE "\n\n    "
+        ENUM
+          ENUM_KW "enum"
+          WHITESPACE " "
+          NAME
+            IDENT "Test3"
+          WHITESPACE " "
+          VARIANT_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            VARIANT
+              NAME
+                IDENT "StillFine"
+              WHITESPACE " "
+              RECORD_FIELD_LIST
+                L_CURLY "{"
+                WHITESPACE "\n            "
+                RECORD_FIELD
+                  NAME
+                    IDENT "def"
+                  COLON ":"
+                  WHITESPACE " "
+                  PATH_TYPE
+                    PATH
+                      PATH_SEGMENT
+                        NAME_REF
+                          IDENT "i32"
+                COMMA ","
+                WHITESPACE "\n        "
+                R_CURLY "}"
+            COMMA ","
+            WHITESPACE "\n    "
+            R_CURLY "}"
+        WHITESPACE "\n\n    "
+        EXPR_STMT
+          BLOCK_EXPR
+            STMT_LIST
+              L_CURLY "{"
+              WHITESPACE "\n        "
+              ENUM
+                COMMENT "// fail again"
+                WHITESPACE "\n        "
+                ENUM_KW "enum"
+                WHITESPACE " "
+                NAME
+                  IDENT "Test4"
+                WHITESPACE " "
+                VARIANT_LIST
+                  L_CURLY "{"
+                  WHITESPACE "\n            "
+                  VARIANT
+                    NAME
+                      IDENT "Nope"
+                    TUPLE_FIELD_LIST
+                      L_PAREN "("
+                      TUPLE_FIELD
+                        PATH_TYPE
+                          PATH
+                            PATH_SEGMENT
+                              NAME_REF
+                                IDENT "i32"
+                      WHITESPACE " "
+                      ERROR
+                  ERROR
+                    L_CURLY "{"
+                    R_CURLY "}"
+                  ERROR
+                    R_PAREN ")"
+                  WHITESPACE " "
+                  COMMENT "//~ ERROR: found `{`"
+                  WHITESPACE "\n                         "
+                  COMMENT "//~^ ERROR: found `{`"
+                  WHITESPACE "\n        "
+                  R_CURLY "}"
+              WHITESPACE "\n    "
+              R_CURLY "}"
+        WHITESPACE "\n    "
+        COMMENT "// still recover later"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            NAME
+              IDENT "bad_syntax"
+          WHITESPACE " "
+          EQ "="
+          WHITESPACE " "
+          ERROR
+            UNDERSCORE "_"
+          SEMICOLON ";"
+        WHITESPACE " "
+        COMMENT "//~ ERROR: expected expression, found reserved identifier `_`"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 95: expected type
+error 95: expected COMMA
+error 96: expected field
+error 98: expected field declaration
+error 371: expected COMMA
+error 372: expected a type
+error 372: expected R_PAREN
+error 372: expected COMMA
+error 372: expected enum variant
+error 374: expected enum variant
+error 508: expected expression

crates/parser/test_data/parser/err/0026_imp_recovery.txt

@@ -0,0 +1,49 @@
+SOURCE_FILE
+  IMPL
+    IMPL_KW "impl"
+    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 "Clone"
+      R_ANGLE ">"
+  WHITESPACE "\n"
+  IMPL
+    IMPL_KW "impl"
+    GENERIC_PARAM_LIST
+      L_ANGLE "<"
+      TYPE_PARAM
+        NAME
+          IDENT "T"
+      R_ANGLE ">"
+    WHITESPACE " "
+    PATH_TYPE
+      PATH
+        PATH_SEGMENT
+          NAME_REF
+            IDENT "OnceCell"
+          GENERIC_ARG_LIST
+            L_ANGLE "<"
+            TYPE_ARG
+              PATH_TYPE
+                PATH
+                  PATH_SEGMENT
+                    NAME_REF
+                      IDENT "T"
+            R_ANGLE ">"
+    WHITESPACE " "
+    ASSOC_ITEM_LIST
+      L_CURLY "{"
+      R_CURLY "}"
+  WHITESPACE "\n"
+error 14: expected trait or type
+error 14: expected `{`

crates/parser/test_data/parser/err/0027_incomplere_where_for.txt

@@ -0,0 +1,29 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE "\n    "
+    WHERE_CLAUSE
+      WHERE_KW "where"
+      WHITESPACE " "
+      WHERE_PRED
+        FOR_KW "for"
+        GENERIC_PARAM_LIST
+          L_ANGLE "<"
+          LIFETIME_PARAM
+            LIFETIME
+              LIFETIME_IDENT "'a"
+          R_ANGLE ">"
+    WHITESPACE "\n"
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 26: expected type
+error 26: expected colon

crates/parser/test_data/parser/err/0029_field_completion.txt

@@ -0,0 +1,36 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      PARAM
+        IDENT_PAT
+          NAME
+            IDENT "a"
+        COLON ":"
+        WHITESPACE " "
+        PATH_TYPE
+          PATH
+            PATH_SEGMENT
+              NAME_REF
+                IDENT "A"
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        FIELD_EXPR
+          PATH_EXPR
+            PATH
+              PATH_SEGMENT
+                NAME_REF
+                  IDENT "a"
+          DOT "."
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 21: expected field name or number

crates/parser/test_data/parser/err/0032_match_arms_inner_attrs.txt

@@ -0,0 +1,205 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        EXPR_STMT
+          MATCH_EXPR
+            MATCH_KW "match"
+            WHITESPACE " "
+            TUPLE_EXPR
+              L_PAREN "("
+              R_PAREN ")"
+            WHITESPACE " "
+            MATCH_ARM_LIST
+              L_CURLY "{"
+              WHITESPACE "\n        "
+              MATCH_ARM
+                WILDCARD_PAT
+                  UNDERSCORE "_"
+                WHITESPACE " "
+                FAT_ARROW "=>"
+                WHITESPACE " "
+                TUPLE_EXPR
+                  L_PAREN "("
+                  R_PAREN ")"
+                COMMA ","
+              WHITESPACE "\n        "
+              MATCH_ARM
+                ATTR
+                  POUND "#"
+                ERROR
+                  BANG "!"
+                ARRAY_EXPR
+                  L_BRACK "["
+                  CALL_EXPR
+                    PATH_EXPR
+                      PATH
+                        PATH_SEGMENT
+                          NAME_REF
+                            IDENT "doc"
+                    ARG_LIST
+                      L_PAREN "("
+                      LITERAL
+                        STRING "\"Not allowed here\""
+                      R_PAREN ")"
+                  R_BRACK "]"
+              WHITESPACE "\n        "
+              MATCH_ARM
+                WILDCARD_PAT
+                  UNDERSCORE "_"
+                WHITESPACE " "
+                FAT_ARROW "=>"
+                WHITESPACE " "
+                TUPLE_EXPR
+                  L_PAREN "("
+                  R_PAREN ")"
+                COMMA ","
+              WHITESPACE "\n    "
+              R_CURLY "}"
+        WHITESPACE "\n\n    "
+        EXPR_STMT
+          MATCH_EXPR
+            MATCH_KW "match"
+            WHITESPACE " "
+            TUPLE_EXPR
+              L_PAREN "("
+              R_PAREN ")"
+            WHITESPACE " "
+            MATCH_ARM_LIST
+              L_CURLY "{"
+              WHITESPACE "\n        "
+              MATCH_ARM
+                WILDCARD_PAT
+                  UNDERSCORE "_"
+                WHITESPACE " "
+                FAT_ARROW "=>"
+                WHITESPACE " "
+                TUPLE_EXPR
+                  L_PAREN "("
+                  R_PAREN ")"
+                COMMA ","
+              WHITESPACE "\n        "
+              MATCH_ARM
+                WILDCARD_PAT
+                  UNDERSCORE "_"
+                WHITESPACE " "
+                FAT_ARROW "=>"
+                WHITESPACE " "
+                TUPLE_EXPR
+                  L_PAREN "("
+                  R_PAREN ")"
+                COMMA ","
+              WHITESPACE "\n        "
+              MATCH_ARM
+                ATTR
+                  POUND "#"
+                ERROR
+                  BANG "!"
+                ARRAY_EXPR
+                  L_BRACK "["
+                  CALL_EXPR
+                    PATH_EXPR
+                      PATH
+                        PATH_SEGMENT
+                          NAME_REF
+                            IDENT "doc"
+                    ARG_LIST
+                      L_PAREN "("
+                      LITERAL
+                        STRING "\"Nor here\""
+                      R_PAREN ")"
+                  R_BRACK "]"
+              WHITESPACE "\n    "
+              R_CURLY "}"
+        WHITESPACE "\n\n    "
+        MATCH_EXPR
+          MATCH_KW "match"
+          WHITESPACE " "
+          TUPLE_EXPR
+            L_PAREN "("
+            R_PAREN ")"
+          WHITESPACE " "
+          MATCH_ARM_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            MATCH_ARM
+              ATTR
+                POUND "#"
+                L_BRACK "["
+                META
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "cfg"
+                  TOKEN_TREE
+                    L_PAREN "("
+                    IDENT "test"
+                    R_PAREN ")"
+                R_BRACK "]"
+              WHITESPACE "\n        "
+              ATTR
+                POUND "#"
+              ERROR
+                BANG "!"
+              ARRAY_EXPR
+                L_BRACK "["
+                CALL_EXPR
+                  PATH_EXPR
+                    PATH
+                      PATH_SEGMENT
+                        NAME_REF
+                          IDENT "doc"
+                  ARG_LIST
+                    L_PAREN "("
+                    LITERAL
+                      STRING "\"Nor here\""
+                    R_PAREN ")"
+                R_BRACK "]"
+            WHITESPACE "\n        "
+            MATCH_ARM
+              WILDCARD_PAT
+                UNDERSCORE "_"
+              WHITESPACE " "
+              FAT_ARROW "=>"
+              WHITESPACE " "
+              TUPLE_EXPR
+                L_PAREN "("
+                R_PAREN ")"
+              COMMA ","
+            WHITESPACE "\n        "
+            MATCH_ARM
+              WILDCARD_PAT
+                UNDERSCORE "_"
+              WHITESPACE " "
+              FAT_ARROW "=>"
+              WHITESPACE " "
+              TUPLE_EXPR
+                L_PAREN "("
+                R_PAREN ")"
+              COMMA ","
+            WHITESPACE "\n    "
+            R_CURLY "}"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 52: expected `[`
+error 52: expected pattern
+error 53: expected FAT_ARROW
+error 78: expected `,`
+error 161: expected `[`
+error 161: expected pattern
+error 162: expected FAT_ARROW
+error 232: expected `[`
+error 232: expected pattern
+error 233: expected FAT_ARROW
+error 250: expected `,`

crates/parser/test_data/parser/err/0033_match_arms_outer_attrs.txt

@@ -0,0 +1,68 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "foo"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        MATCH_EXPR
+          MATCH_KW "match"
+          WHITESPACE " "
+          TUPLE_EXPR
+            L_PAREN "("
+            R_PAREN ")"
+          WHITESPACE " "
+          MATCH_ARM_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            MATCH_ARM
+              WILDCARD_PAT
+                UNDERSCORE "_"
+              WHITESPACE " "
+              FAT_ARROW "=>"
+              WHITESPACE " "
+              TUPLE_EXPR
+                L_PAREN "("
+                R_PAREN ")"
+              COMMA ","
+            WHITESPACE "\n        "
+            MATCH_ARM
+              WILDCARD_PAT
+                UNDERSCORE "_"
+              WHITESPACE " "
+              FAT_ARROW "=>"
+              WHITESPACE " "
+              TUPLE_EXPR
+                L_PAREN "("
+                R_PAREN ")"
+              COMMA ","
+            WHITESPACE "\n        "
+            MATCH_ARM
+              ATTR
+                POUND "#"
+                L_BRACK "["
+                META
+                  PATH
+                    PATH_SEGMENT
+                      NAME_REF
+                        IDENT "cfg"
+                  TOKEN_TREE
+                    L_PAREN "("
+                    IDENT "test"
+                    R_PAREN ")"
+                R_BRACK "]"
+            WHITESPACE "\n    "
+            R_CURLY "}"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"
+error 80: expected pattern
+error 80: expected FAT_ARROW
+error 80: expected expression

crates/parser/test_data/parser/err/0034_bad_box_pattern.txt

@@ -0,0 +1,96 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            REF_KW "ref"
+            WHITESPACE " "
+            ERROR
+              BOX_KW "box"
+        WHITESPACE " "
+        EXPR_STMT
+          BIN_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "i"
+            WHITESPACE " "
+            EQ "="
+            WHITESPACE " "
+            TUPLE_EXPR
+              L_PAREN "("
+              R_PAREN ")"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            MUT_KW "mut"
+            WHITESPACE " "
+            ERROR
+              BOX_KW "box"
+        WHITESPACE " "
+        EXPR_STMT
+          BIN_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "i"
+            WHITESPACE " "
+            EQ "="
+            WHITESPACE " "
+            TUPLE_EXPR
+              L_PAREN "("
+              R_PAREN ")"
+          SEMICOLON ";"
+        WHITESPACE "\n    "
+        LET_STMT
+          LET_KW "let"
+          WHITESPACE " "
+          IDENT_PAT
+            REF_KW "ref"
+            WHITESPACE " "
+            MUT_KW "mut"
+            WHITESPACE " "
+            ERROR
+              BOX_KW "box"
+        WHITESPACE " "
+        EXPR_STMT
+          BIN_EXPR
+            PATH_EXPR
+              PATH
+                PATH_SEGMENT
+                  NAME_REF
+                    IDENT "i"
+            WHITESPACE " "
+            EQ "="
+            WHITESPACE " "
+            TUPLE_EXPR
+              L_PAREN "("
+              R_PAREN ")"
+          SEMICOLON ";"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n\n"
+error 24: expected a name
+error 27: expected SEMICOLON
+error 48: expected a name
+error 51: expected SEMICOLON
+error 76: expected a name
+error 79: expected SEMICOLON