re PR c/14649 (atan(1.0) should not be a constant expression)

re PR c/14649 (atan(1.0) should not be a constant expression)

	PR c/14649
	* c-typeck.c (require_constant_value, require_constant_elements):
	Move declarations to the top of the file.
	(build_function_call): If we require a constant value, fold with
	fold_initializer.  If the result is a constant, and the function
	wasn't called using __builtin_foo, issue a pedantic warning.
	(build_unary_op): If we require a constant value, fold tree with
	fold_initializer.
	(build_binary_op): Use require_constant_value to determine whether
	to call fold or fold_initializer.

	* gcc.dg/pr14649-1.c: New test case.

From-SVN: r82705