Functions which take parameter that are declared non-null

[th-otto]

Some function (like strlen) have their parameters declared as being non-null, so the compiler can warn about it when it knows that a null-argument is passed to it. But of course, the compiler cannot always determine whether a argument is null or not. But it now warns about it, when you check the argument in the implementation. I added a fix for it long time ago, eg. in

86d54fb#diff-0d90af3a410d3fd6d8162e2526179c68988bb7e1140374bf7411d9fbc717e224

However, that seems to be incomplete. The warning is gone, but the check seems to be also gone:

_strlen:
[00000000] 206f 0004                 movea.l    4(a7),a0
[00000004] 5288                      addq.l     #1,a0
[00000006] 2008                      move.l     a0,d0
.L2:
[00000008] 4a28 ffff                 tst.b      -1(a0)
[0000000c] 6606                      bne.s      .L7
[0000000e] 91c0                      suba.l     d0,a0
[00000010] 2008                      move.l     a0,d0
[00000012] 4e75                      rts
.L7:
[00000014] 5288                      addq.l     #1,a0
[00000016] 60f0                      bra.s      .L2

Not sure which behaviour is better. It is definitely an application error if a null argument is passed to strlen, and on other systems that will also core-dump. So should be somehow make sure that the NULL check remains intact like it was when using older compiler versions? Or should we remove that check altogether, and let the application crash? If it should remain, i wonder how we can achieve that without messing with the declaration in string.h.