From b35ec6e15ad54da56d8caa9d614ec9519cb01cb7 Mon Sep 17 00:00:00 2001 From: msebor Date: Wed, 14 Feb 2018 22:02:43 +0000 Subject: PR middle-end/84108 - incorrect -Wattributes warning for packed/aligned conflict on struct members gcc/ChangeLog: PR c/84108 * attribs.c (diag_attr_exclusions): Consider the exclusion(s) that correspond to the kind of a declaration. gcc/testsuite/ChangeLog: PR c/84108 * gcc.dg/Wattributes-8.c: New test. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@257674 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/testsuite/gcc.dg/Wattributes-8.c | 38 ++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/Wattributes-8.c (limited to 'gcc/testsuite/gcc.dg/Wattributes-8.c') diff --git a/gcc/testsuite/gcc.dg/Wattributes-8.c b/gcc/testsuite/gcc.dg/Wattributes-8.c new file mode 100644 index 00000000000..a4b4c00c08f --- /dev/null +++ b/gcc/testsuite/gcc.dg/Wattributes-8.c @@ -0,0 +1,38 @@ +/* PR middle-end/84108 - incorrect -Wattributes warning for packed/aligned + conflict on struct members + { dg-do compile } + { dg-options "-Wall -Wattributes" } */ + +#define ATTR(list) __attribute__ (list) +#define ASSERT(e) _Static_assert (e, #e) + +/* GCC is inconsistent in how it treats attribute aligned between + variable and member declarations. Attribute aligned alone is + sufficient to reduce a variable's alignment requirement but + the attribute must be paired with packed to have the same + effect on a member. Worse, declaring a variable both aligned + and packed emits a warning. */ + +/* Avoid exercising this since emitting a warning for these given + the requirement for members seems like a misfeature: + int a ATTR ((packed, aligned (2))); // -Wattributes + int b ATTR ((aligned (2), packed)); // -Wattributes + ASSERT (_Alignof (a) == 2); + ASSERT (_Alignof (b) == 2); */ + +int c ATTR ((aligned (2))); // okay (reduces alignment) +ASSERT (_Alignof (c) == 2); + +struct { + int a ATTR ((packed, aligned (2))); /* { dg-bogus "\\\[-Wattributes" } */ + int b ATTR ((aligned (2), packed)); /* { dg-bogus "\\\[-Wattributes" } */ + + /* Avoid exercising this since the attribute has no effect yet + there is no warning. + int c ATTR ((aligned (2))); // missing warning? */ +} s; + +ASSERT (_Alignof (s.a) == 2); +ASSERT (_Alignof (s.b) == 2); + +/* ASSERT (_Alignof (s.c) == 4); */ -- cgit v1.2.1