add constcast and immutable free

compiler/checker/checker.odin

@@ -5187,6 +5187,16 @@ infer_expr :: proc(
 					_ = pop(&stack)
 					continue
 				}
+				if is_intrinsic_call(checker, expr, "constcast") {
+					if len(expr.args) == 1 {
+						operand := infer_nested_expr(checker, expr.args[0], locals, pkg, file, demanded, local_types)
+						last, _ = types.restore_mutability(&checker.module.types, operand)
+					} else {
+						last = types.INVALID
+					}
+					_ = pop(&stack)
+					continue
+				}
 				if is_intrinsic_call(checker, expr, "compile_error") {
 					last = types.VOID
 					_ = pop(&stack)
@@ -9056,6 +9066,17 @@ build_expr :: proc(
 					append(&stack, Build_Expr_Frame{expr=expr.args[1], expected=types.INVALID, template=ast.INVALID_FUNCTION})
 					continue
 				}
+				if is_intrinsic_call(checker, expr, "constcast") {
+					if len(expr.args) != 1 {
+						id := source.addf(checker.diagnostics, expr.span, "constcast! expects 1 argument, got %d", len(expr.args))
+						last = invalid_hir_expr(checker, expr.span, id)
+						_ = pop(&stack)
+						continue
+					}
+					stack[frame_index].stage = 10
+					append(&stack, Build_Expr_Frame{expr=expr.args[0], expected=types.INVALID, template=ast.INVALID_FUNCTION})
+					continue
+				}
 				if is_intrinsic_call(checker, expr, "compile_error") {
 					message := "compile_error! requires one comptime string argument"
 					if len(expr.args) == 1 {
@@ -9716,6 +9737,24 @@ build_expr :: proc(
 			}
 			_ = pop(&stack)
 		}
+		if frame.stage == 10 {
+			result, ok := types.restore_mutability(&checker.module.types, checker.module.exprs[last].type)
+			if !ok {
+				id := source.add(checker.diagnostics, expr.span, "constcast! operand must be a pointer, optional pointer, or slice")
+				last = invalid_hir_expr(checker, expr.span, id)
+			} else {
+				last = add_hir_expr(checker, hir.Expr{
+					kind=.Const_Cast,
+					span=expr.span,
+					type=result,
+					left=last,
+					target=hir.INVALID_REF,
+					right=hir.INVALID_EXPR,
+					diagnostic=source.INVALID_DIAGNOSTIC,
+				})
+			}
+			_ = pop(&stack)
+		}
 	}
 	return last
 }