From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Bug: "typeof(*p) *" drops const Date: Fri, 6 Sep 2013 07:53:21 -0700 Message-ID: <20130906145320.GA26549@leaf> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from relay4-d.mail.gandi.net ([217.70.183.196]:44738 "EHLO relay4-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922Ab3IFOx1 (ORCPT ); Fri, 6 Sep 2013 10:53:27 -0400 Content-Disposition: inline Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: linux-sparse@vger.kernel.org Cc: paulmck@linux.vnet.ibm.com The following test case compiles via GCC with no errors or warnings, but generates a type warning with sparse: void f(void); void f(void) { const int *pc; typeof(*pc) *pc2 = pc; } Sparse says: typeof-const.c:5:24: warning: incorrect type in initializer (different modifiers) typeof-const.c:5:24: expected int *pc2 typeof-const.c:5:24: got int const *pc Since pc has type "const int *", "typeof(*pc) *" should also have type "const int *", not "int *". The actual use case for which this came up occurred in the kernel when using the equivalent of: typeof(*p) __attribute__((address_space(0),force)) * to generate the same type as p but in address space 0 rather than whatever address space p had. That worked fine for non-const pointers, but const pointers lost their constness, resulting in constness warnings. The following patch adds a test case for this; please apply once sparse handles this case correctly: ---------->8---------- From: Josh Triplett Subject: [PATCH] validation: Add new test case for typeof(*ptr) preserving const If ptr has type "const foo *", then "typeof(*ptr) *" should also have type "const foo *", not "foo *". Add a test to ensure that. Signed-off-by: Josh Triplett --- validation/typeof-const.c | 9 +++++++++ 1 file changed, 9 insertions(+) create mode 100644 validation/typeof-const.c diff --git a/validation/typeof-const.c b/validation/typeof-const.c new file mode 100644 index 0000000..d02d39a --- /dev/null +++ b/validation/typeof-const.c @@ -0,0 +1,9 @@ +void f(void); +void f(void) +{ + const int *pc; + typeof(*pc) *pc2 = pc; +} +/* + * check-name: typeof-const.c + */ -- 1.8.4.rc3