re PR c++/85662 ("error: non-constant condition for static assertion" from __builtin_offsetof in C++)
PR c++/85662
* c-common.h (fold_offsetof_1): Removed.
(fold_offsetof): Add TYPE argument defaulted to size_type_node and
CTX argument defaulted to ERROR_MARK.
* c-common.c (fold_offsetof_1): Renamed to ...
(fold_offsetof): ... this. Remove wrapper function. Add TYPE
argument, convert the pointer constant to TYPE and use size_binop
with PLUS_EXPR instead of fold_build_pointer_plus if type is not
a pointer type. Adjust recursive calls.
* c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than
fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the
fold_convert_loc.
* c-typeck.c (build_unary_op): Use fold_offsetof rather than
fold_offsetof_1, pass argtype as TYPE to it and drop the
fold_convert_loc.
* cp-gimplify.c (cp_fold): Use fold_offsetof rather than
fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the
fold_convert.
* g++.dg/ext/offsetof2.C: New test.
From-SVN: r260119
