c++/contracts: ICE with contract assert on non-empty statement [PR 117579]

c++/contracts: ICE with contract assert on non-empty statement [PR 117579]

Contract assert is an attribute on an empty statement. Currently we assert
that the statement is empty before emitting the assertion. This has been
changed to a conditional check that the statement is empty before the
assertion is emitted.

	PR c++/117579

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_statement): Replace assertion with a
	conditional check that the statement containing a contract assert
	is empty.

gcc/testsuite/ChangeLog:

	* g++.dg/contracts/pr117579.C: New test.

Signed-off-by: Nina Ranns <dinka.ranns@gmail.com>
Reviewed-by: Jason Merrill <jason@redhat.com>