Introduce hardbool attribute for C

This patch introduces hardened booleans in C.  The hardbool attribute,
when attached to an integral type, turns it into an enumerate type
with boolean semantics, using the named or implied constants as
representations for false and true.

Expressions of such types decay to _Bool, trapping if the value is
neither true nor false, and _Bool can convert implicitly back to them.
Other conversions go through _Bool first.


for  gcc/c-family/ChangeLog

	* c-attribs.cc (c_common_attribute_table): Add hardbool.
	(handle_hardbool_attribute): New.
	(type_valid_for_vector_size): Reject hardbool.
	* c-common.cc (convert_and_check): Skip warnings for convert
	and check for hardbool.
	(c_hardbool_type_attr_1): New.
	* c-common.h (c_hardbool_type_attr): New.

for  gcc/c/ChangeLog

	* c-typeck.cc (convert_lvalue_to_rvalue): Decay hardbools.
	* c-convert.cc (convert): Convert to hardbool through
	truthvalue.
	* c-decl.cc (check_bitfield_type_and_width): Skip enumeral
	truncation warnings for hardbool.
	(finish_struct): Propagate hardbool attribute to bitfield
	types.
	(digest_init): Convert to hardbool.

for  gcc/ChangeLog

	* doc/extend.texi (hardbool): New type attribute.
	* doc/invoke.texi (-ftrivial-auto-var-init): Document
	representation vs values.

for  gcc/testsuite/ChangeLog

	* gcc.dg/hardbool-err.c: New.
	* gcc.dg/hardbool-trap.c: New.
	* gcc.dg/torture/hardbool.c: New.
	* gcc.dg/torture/hardbool-s.c: New.
	* gcc.dg/torture/hardbool-us.c: New.
	* gcc.dg/torture/hardbool-i.c: New.
	* gcc.dg/torture/hardbool-ul.c: New.
	* gcc.dg/torture/hardbool-ll.c: New.
	* gcc.dg/torture/hardbool-5a.c: New.
	* gcc.dg/torture/hardbool-s-5a.c: New.
	* gcc.dg/torture/hardbool-us-5a.c: New.
	* gcc.dg/torture/hardbool-i-5a.c: New.
	* gcc.dg/torture/hardbool-ul-5a.c: New.
	* gcc.dg/torture/hardbool-ll-5a.c: New.

0 files changed, 0 insertions, 0 deletions