PR c/24581
	* c-typeck.c (build_binary_op): Handle arithmetic between one real
	and one complex operand specially.
	* tree-complex.c (some_nonzerop): Do not identify a real value as
	zero if flag_signed_zeros.

testsuite:
	* gcc.dg/torture/complex-sign.h: New header.
	* gcc.dg/torture/complex-sign-add.c,
	gcc.dg/torture/complex-sign-mixed-add.c,
	gcc.dg/torture/complex-sign-mixed-div.c,
	gcc.dg/torture/complex-sign-mixed-mul.c,
	gcc.dg/torture/complex-sign-mixed-sub.c,
	gcc.dg/torture/complex-sign-mul.c,
	gcc.dg/torture/complex-sign-sub.c: New tests.

From-SVN: r147281