From fba303ed8c190cc2b8695d737efd7af409596398 Mon Sep 17 00:00:00 2001 From: Martin Sebor Date: Wed, 14 Feb 2018 22:02:43 +0000 Subject: [PATCH] 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. From-SVN: r257674 --- gcc/ChangeLog | 6 +++++ gcc/attribs.c | 16 ++++++++++++ gcc/testsuite/ChangeLog | 5 ++++ gcc/testsuite/gcc.dg/Wattributes-8.c | 38 ++++++++++++++++++++++++++++ 4 files changed, 65 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/Wattributes-8.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 97067a3ffe2..e16acd45413 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2018-02-14 Martin Sebor + + PR c/84108 + * attribs.c (diag_attr_exclusions): Consider the exclusion(s) + that correspond to the kind of a declaration. + 2018-02-14 John David Anglin PR target/83984 diff --git a/gcc/attribs.c b/gcc/attribs.c index 2cac9c403b4..140863be1d9 100644 --- a/gcc/attribs.c +++ b/gcc/attribs.c @@ -410,6 +410,22 @@ diag_attr_exclusions (tree last_decl, tree node, tree attrname, if (!lookup_attribute (excl->name, attrs[i])) continue; + /* An exclusion may apply either to a function declaration, + type declaration, or a field/variable declaration, or + any subset of the three. */ + if (TREE_CODE (node) == FUNCTION_DECL + && !excl->function) + continue; + + if (TREE_CODE (node) == TYPE_DECL + && !excl->type) + continue; + + if ((TREE_CODE (node) == FIELD_DECL + || TREE_CODE (node) == VAR_DECL) + && !excl->variable) + continue; + found = true; /* Print a note? */ diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index e3d1cec40f1..2044efc6997 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2018-02-14 Martin Sebor + + PR c/84108 + * gcc.dg/Wattributes-8.c: New test. + 2018-02-14 Janus Weil PR fortran/84385 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); */ -- 2.30.2