We're currently neglecting to set the ALIGNOF_EXPR_STD_P flag on an
ALIGNOF_EXPR when its operand is an expression. This leads to us
handling alignof(expr) as if it were written __alignof__(expr), and
returning the preferred alignment instead of the ABI alignment. In the
testcase below, this causes the first and third static_assert to fail on
x86.
gcc/cp/ChangeLog:
PR c++/88115
* cp-tree.h (cxx_sizeof_or_alignof_expr): Add bool parameter.
* decl.c (fold_sizeof_expr): Pass false to
cxx_sizeof_or_alignof_expr.
* parser.c (cp_parser_unary_expression): Pass std_alignof to
cxx_sizeof_or_alignof_expr.
* pt.c (tsubst_copy): Pass false to cxx_sizeof_or_alignof_expr.
(tsubst_copy_and_build): Pass std_alignof to
cxx_sizeof_or_alignof_expr.
* typeck.c (cxx_alignof_expr): Add std_alignof bool parameter
and pass it to cxx_sizeof_or_alignof_type. Set ALIGNOF_EXPR_STD_P
appropriately.
(cxx_sizeof_or_alignof_expr): Add std_alignof bool parameter
and pass it to cxx_alignof_expr. Assert op is either
SIZEOF_EXPR or ALIGNOF_EXPR.
libcc1/ChangeLog:
PR c++/88115
* libcp1plugin.cc (plugin_build_unary_expr): Pass true to
cxx_sizeof_or_alignof_expr.
gcc/testsuite/ChangeLog:
PR c++/88115
* g++.dg/cpp0x/alignof6.C: New test.
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