checker: check for reserved type names in `for in` (fix #14072) (#14212)

vlib/v/checker/checker.v

@@ -38,8 +38,9 @@ pub const (
 	valid_comptime_not_user_defined  = all_valid_comptime_idents()
 	array_builtin_methods            = ['filter', 'clone', 'repeat', 'reverse', 'map', 'slice',
 		'sort', 'contains', 'index', 'wait', 'any', 'all', 'first', 'last', 'pop']
-	reserved_type_names              = ['bool', 'char', 'i8', 'i16', 'int', 'i64', 'byte', 'u16',
-		'u32', 'u64', 'f32', 'f64', 'map', 'string', 'rune']
+	// TODO: remove `byte` from this list when it is no longer supported
+	reserved_type_names              = ['byte', 'bool', 'char', 'i8', 'i16', 'int', 'i64', 'u8',
+		'u16', 'u32', 'u64', 'f32', 'f64', 'map', 'string', 'rune']
 	vroot_is_deprecated_message      = '@VROOT is deprecated, use @VMODROOT or @VEXEROOT instead'
 )
 

vlib/v/checker/for.v

@@ -38,9 +38,15 @@ fn (mut c Checker) for_in_stmt(mut node ast.ForInStmt) {
 	typ_idx := typ.idx()
 	if node.key_var.len > 0 && node.key_var != '_' {
 		c.check_valid_snake_case(node.key_var, 'variable name', node.pos)
+		if node.key_var in reserved_type_names {
+			c.error('invalid use of reserved type `$node.key_var` as key name', node.pos)
+		}
 	}
 	if node.val_var.len > 0 && node.val_var != '_' {
 		c.check_valid_snake_case(node.val_var, 'variable name', node.pos)
+		if node.val_var in reserved_type_names {
+			c.error('invalid use of reserved type `$node.val_var` as value name', node.pos)
+		}
 	}
 	if node.is_range {
 		high_type := c.expr(node.high)

vlib/v/checker/tests/for_in_with_reserved_type_names.out

@@ -0,0 +1,13 @@
+vlib/v/checker/tests/for_in_with_reserved_type_names.vv:2:6: error: invalid use of reserved type `rune` as value name
+    1 | fn main() {
+    2 |     for rune in 'runes' {
+      |         ~~~~
+    3 |         println(rune)
+    4 |     }
+vlib/v/checker/tests/for_in_with_reserved_type_names.vv:6:6: error: invalid use of reserved type `char` as key name
+    4 |     }
+    5 | 
+    6 |     for char, c in 'runes' {
+      |         ~~~~
+    7 |         println(c)
+    8 |         println(char)

vlib/v/checker/tests/for_in_with_reserved_type_names.vv

@@ -0,0 +1,10 @@
+fn main() {
+	for rune in 'runes' {
+		println(rune)
+	}
+
+	for char, c in 'runes' {
+		println(c)
+		println(char)
+	}
+}

vlib/v/doc/utils.v

@@ -85,9 +85,9 @@ pub fn merge_doc_comments(comments []DocComment) string {
 
 		mut is_horizontalrule := false
 		line_no_spaces := line_trimmed.replace(' ', '')
-		for char in ['-', '=', '*', '_', '~'] {
-			if line_no_spaces.starts_with(char.repeat(3))
-				&& line_no_spaces.count(char) == line_no_spaces.len {
+		for ch in ['-', '=', '*', '_', '~'] {
+			if line_no_spaces.starts_with(ch.repeat(3))
+				&& line_no_spaces.count(ch) == line_no_spaces.len {
 				is_horizontalrule = true
 				break
 			}

vlib/v/gen/js/js.v

@@ -3376,11 +3376,11 @@ fn (mut g JsGen) gen_string_literal(it ast.StringLiteral) {
 		g.writeln('return s; })()')
 	} else {
 		g.write('"')
-		for char in text {
-			if char == `\n` {
+		for ch in text {
+			if ch == `\n` {
 				g.write('\\n')
 			} else {
-				g.write('$char.ascii_str()')
+				g.write('$ch.ascii_str()')
 			}
 		}
 		g.write('"')

vlib/v/tests/struct_init_with_fixed_array_field_test.v

@@ -12,8 +12,8 @@ mut:
 fn test_struct_init_with_fixed_array_field() {
 	s := 'xoxooxxxo'
 	mut board := [9]Piece{}
-	for i, char in s {
-		board[i] = match char {
+	for i, ch in s {
+		board[i] = match ch {
 			`x` { Piece.x }
 			`o` { Piece.o }
 			else { Piece.free }

vlib/x/json2/scanner_test.v

@@ -40,9 +40,9 @@ fn test_str_invalid_escape() {
 }
 
 fn test_str_invalid_must_be_escape() {
-	for char in important_escapable_chars {
+	for ch in important_escapable_chars {
 		mut sc := Scanner{
-			text: [u8(`"`), `t`, char, `"`]
+			text: [u8(`"`), `t`, ch, `"`]
 		}
 		tok := sc.scan()
 		assert tok.kind == .error