cgen: fix short circuiting behaviour of logical expressions, when several PrefixExpr's are used in if conditions (#16660)

vlib/v/gen/c/infix.v

@@ -886,6 +886,28 @@ fn (mut g Gen) infix_expr_and_or_op(node ast.InfixExpr) {
 			g.inside_ternary = prev_inside_ternary
 			return
 		}
+	} else if node.right is ast.PrefixExpr && g.inside_ternary == 0 {
+		prefix := node.right
+		if prefix.op == .not && prefix.right is ast.CallExpr {
+			call_expr := prefix.right as ast.CallExpr
+			if call_expr.or_block.kind != .absent {
+				prev_inside_ternary := g.inside_ternary
+				g.inside_ternary = 0
+				tmp := g.new_tmp_var()
+				cur_line := g.go_before_stmt(0).trim_space()
+				g.empty_line = true
+				g.write('bool ${tmp} = (')
+				g.expr(node.left)
+				g.writeln(');')
+				g.set_current_pos_as_last_stmt_pos()
+				g.write('${cur_line} ${tmp} ${node.op.str()} ')
+				g.infix_left_var_name = '!${tmp}'
+				g.expr(node.right)
+				g.infix_left_var_name = ''
+				g.inside_ternary = prev_inside_ternary
+				return
+			}
+		}
 	}
 	g.gen_plain_infix_expr(node)
 }

vlib/v/tests/inout/printing_result_in_infix_expr2.out

@@ -0,0 +1,4 @@
+True 2
+ok
+True 3
+False 3

vlib/v/tests/inout/printing_result_in_infix_expr2.vv

@@ -0,0 +1,29 @@
+fn false_(n int) !bool {
+	println('False ${n}')
+	return false
+}
+
+fn true_(n int) !bool {
+	println('True ${n}')
+	return true
+}
+
+fn true_2() !bool {
+	println('True')
+	return true
+}
+
+fn test() ! {
+	if true_(2)! || !false_(2)! {
+		println('ok')
+	}
+
+	if false {
+	} else if (true_(3)! || !false_(3)!) && false_(3)! {
+		println('ok2')
+	}
+}
+
+fn main() {
+	test() or { panic(err) }
+}