What does Z["ack"] = 5 mean?

[David Goodenough]

>From article <14999 at agate.BERKELEY.EDU>, by laba-3aw at web.berkeley.edu (Sam Shen):
> Exactly what does this mean:
> 
> main()
> {
> 	char Z;
> 
> 	Z["ack!"] = 5;
> }
> 
> This doesn't look right to me.

Given that a[b] is (in some compilers [1]) considered to be *(a+b), your
Z["ack!"] = 5 can be considered as *("ack!" + Z) = 5, which equates to
"ack!"[Z] = 5. OK so far - this will work on most machines where strings
do not become part of a write only memory segment (Do any architectures
exist where strings become shared and read only??). Reading such a value
however, should be legal (at least that's what I interpret K&R to say).

[1] It is interesting to note that Greenhills CC (what we have here)
chokes on this sort of thing, generating the following:

"foo.c", line 5: Indexing not allowed
"foo.c", line 5: Type mismatch

Is this compiler broken W.R.T. dpANSI?? (not that I do this, it just happens
a lot in the obfuscated C contest :-)
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