* c-typeck.c (build_array_ref): Don't check for index == 0.  Make
	checks for neither argument being an array or pointer (swapping
	the arguments if necessary), the array argument being a pointer to
	or array of functions and for -Wchar-subscripts warnings upfront.

testsuite:
	* gcc.dg/Wchar-subscripts-1.c, gcc.dg/array-8.c: New tests.
	* gcc.dg/pointer-arith-1.c, gcc.dg/pointer-arith-2.c,
	gcc.dg/pointer-arith-3.c, gcc.dg/pointer-arith-4.c: Update
	expected diagnostics.

From-SVN: r90969