parser: improve printing of unexpected tokens (#8654)

vlib/v/checker/tests/trailing_comma_struct_attr.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/trailing_comma_struct_attr.vv:3:31: error: unexpected `]`, expecting `name`
+vlib/v/checker/tests/trailing_comma_struct_attr.vv:3:31: error: unexpected token `]`, expecting name
     1 | struct User {
     2 |     name string
     3 |     jobs []string [json:jobss;]

vlib/v/parser/fn.v

@@ -527,7 +527,7 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 	no_body := p.tok.kind != .lcbr
 	same_line = p.tok.line_nr == p.prev_tok.line_nr
 	if no_body && same_line {
-		p.error_with_pos('unexpected `$p.tok.kind` after anonymous function signature, expecting `{`',
+		p.error_with_pos('unexpected $p.tok after anonymous function signature, expecting `{`',
 			p.tok.position())
 	}
 	mut label_names := []string{}

vlib/v/parser/lock.v

@@ -15,7 +15,7 @@ fn (mut p Parser) lock_expr() ast.LockExpr {
 		}
 		is_rlock := p.tok.kind == .key_rlock
 		if !is_rlock && p.tok.kind != .key_lock {
-			p.error_with_pos('unexpected `$p.tok.lit`; `lock` or `rlock` expected', p.tok.position())
+			p.error_with_pos('unexpected $p.tok, expected `lock` or `rlock`', p.tok.position())
 		}
 		p.next()
 		for p.tok.kind == .name {

vlib/v/parser/parser.v

@@ -424,14 +424,16 @@ fn (mut p Parser) check(expected token.Kind) {
 	// }
 	if p.tok.kind == expected {
 		p.next()
-	} else if p.tok.kind == .name {
-		p.error('unexpected name `$p.tok.lit`, expecting `$expected.str()`')
 	} else {
 		if expected == .name {
 			p.name_error = true
 		}
-		label := if token.is_key(p.tok.lit) { 'keyword ' } else { '' }
-		p.error('unexpected $label`$p.tok.kind.str()`, expecting `$expected.str()`')
+		mut s := expected.str()
+		// quote keywords, punctuation, operators
+		if token.is_key(s) || (s.len > 0 && !s[0].is_letter()) {
+			s = '`$s`'
+		}
+		p.error('unexpected $p.tok, expecting $s')
 	}
 }
 
@@ -841,7 +843,7 @@ fn (mut p Parser) attributes() {
 				p.next()
 				break
 			}
-			p.error('unexpected `$p.tok.kind.str()`, expecting `;`')
+			p.error('unexpected $p.tok, expecting `;`')
 			return
 		}
 		p.next()

vlib/v/parser/pratt.v

@@ -297,8 +297,7 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 		else {
 			if p.tok.kind != .eof {
 				// eof should be handled where it happens
-				p.error_with_pos('invalid expression: unexpected `$p.tok.kind.str()` token',
-					p.tok.position())
+				p.error_with_pos('invalid expression: unexpected $p.tok', p.tok.position())
 				return ast.Expr{}
 			}
 		}

vlib/v/parser/tests/postfix_inc.out

@@ -1,4 +1,4 @@
-vlib/v/parser/tests/postfix_inc.vv:3:1: error: `++` must be on the same line as the previous token
+vlib/v/parser/tests/postfix_inc.vv:3:1: error: token `++` must be on the same line as the previous token
     1 | mut v := 4
     2 | _ = v
     3 | ++v

vlib/v/parser/tests/struct_field_expected.out

@@ -1,4 +1,4 @@
-vlib/v/parser/tests/struct_field_expected.vv:6:2: error: unexpected `.`, expecting struct field name
+vlib/v/parser/tests/struct_field_expected.vv:6:2: error: unexpected token `.`, expecting struct field name
     4 | 
     5 | x = {
     6 |     .a : 'Alpha'

vlib/v/parser/tests/struct_update_err.out

@@ -1,4 +1,4 @@
-vlib/v/parser/tests/struct_update_err.vv:15:3: error: unexpected `...`, expecting `name`
+vlib/v/parser/tests/struct_update_err.vv:15:3: error: unexpected token `...`, expecting name
    13 |     f2 := Foo{
    14 |         name: 'f2'
    15 |         ...f

vlib/v/parser/tests/uncomplete_module_call_err.out

@@ -1,4 +1,4 @@
-vlib/v/parser/tests/uncomplete_module_call_err.vv:7:1: error: unexpected `}`, expecting `name`
+vlib/v/parser/tests/uncomplete_module_call_err.vv:7:1: error: unexpected token `}`, expecting name
     5 | fn main() {
     6 |     os.
     7 | }

vlib/v/parser/tests/unexpected_expr.out

@@ -0,0 +1,3 @@
+vlib/v/parser/tests/unexpected_expr.vv:1:5: error: invalid expression: unexpected keyword `break`
+    1 | _ = break
+      |     ~~~~~

vlib/v/parser/tests/unexpected_expr.vv

@@ -0,0 +1 @@
+_ = break

vlib/v/token/token.v

@@ -319,6 +319,7 @@ pub fn (t Kind) is_assign() bool {
 	return t in token.assign_tokens
 }
 
+// note: used for some code generation, so no quoting
 pub fn (t Kind) str() string {
 	return token.token_str[int(t)]
 }
@@ -329,10 +330,15 @@ pub fn (t Token) str() string {
 		eprintln('missing token kind string')
 	} else if !s[0].is_letter() {
 		// punctuation, operators
-		return '`$s`' 
+		return 'token `$s`'
+	}
+	if is_key(t.lit) {
+		s = 'keyword'
+	}
+	if t.lit != '' {
+		// string contents etc
+		s += ' `$t.lit`'
 	}
-	// string contents etc
-	if t.lit != '' { s += ' `$t.lit`' }
 	return s
 }