checker, cgen: allow comptime ident is array of types (#18765)

Author: phoebe

vlib/v/checker/comptime.v

@@ -743,7 +743,11 @@ fn (mut c Checker) comptime_if_branch(cond ast.Expr, pos token.Pos) ComptimeBran
 					}
 				}
 				.key_in, .not_in {
-					if cond.left in [ast.SelectorExpr, ast.TypeNode] && cond.right is ast.ArrayInit {
+					if cond.left is ast.Ident {
+						c.expr(cond.left)
+					}
+					if cond.left in [ast.TypeNode, ast.SelectorExpr, ast.Ident]
+						&& cond.right is ast.ArrayInit {
 						for expr in cond.right.exprs {
 							if expr !in [ast.ComptimeType, ast.TypeNode] {
 								c.error('invalid `\$if` condition, only types are allowed',

vlib/v/checker/tests/run/comptime_ident_in_typearray.run.out

@@ -0,0 +1,4 @@
+str
+this is an else block
+32-bit number
+32-bit number

vlib/v/checker/tests/run/comptime_ident_in_typearray.vv

@@ -0,0 +1,16 @@
+fn test[T](val T) string {
+	$if val is string {
+		return val
+	} $else $if val in [i32, u32] {
+		return '32-bit number'
+	} $else {
+		return 'this is an else block'
+	}
+}
+
+fn main() {
+	println(test('str'))
+	println(test(7))
+	println(test(u32(7)))
+	println(test(i32(7)))
+}

vlib/v/gen/c/comptime.v

@@ -617,7 +617,8 @@ fn (mut g Gen) comptime_if_cond(cond ast.Expr, pkg_exist bool) (bool, bool) {
 					}
 				}
 				.key_in, .not_in {
-					if cond.left in [ast.TypeNode, ast.SelectorExpr] && cond.right is ast.ArrayInit {
+					if cond.left in [ast.TypeNode, ast.SelectorExpr, ast.Ident]
+						&& cond.right is ast.ArrayInit {
 						checked_type := g.get_expr_type(cond.left)
 
 						for expr in cond.right.exprs {
@@ -632,9 +633,8 @@ fn (mut g Gen) comptime_if_cond(cond ast.Expr, pkg_exist bool) (bool, bool) {
 								}
 							} else if expr is ast.TypeNode {
 								got_type := g.unwrap_generic(expr.typ)
-								is_true := checked_type.idx() == got_type.idx()
-									&& checked_type.has_flag(.option) == got_type.has_flag(.option)
-								if is_true {
+								if checked_type.idx() == got_type.idx()
+									&& checked_type.has_flag(.option) == got_type.has_flag(.option) {
 									if cond.op == .key_in {
 										g.write('1')
 									} else {
@@ -650,9 +650,6 @@ fn (mut g Gen) comptime_if_cond(cond ast.Expr, pkg_exist bool) (bool, bool) {
 							g.write('0')
 						}
 						return cond.op == .not_in, true
-					} else {
-						g.write('1')
-						return true, true
 					}
 				}
 				.gt, .lt, .ge, .le {