Martin Gregorie  writes:
>On Wed, 06 Jan 2021 15:15:36 +0000, Scott Lurndal wrote:
>
>> Martin Gregorie  writes:
>>>On Tue, 05 Jan 2021 14:06:57 -0700, Peter Flass wrote:
>>>
>>>> You shouldn’t need declarations in C unless you’re using one of those
>>>> new-fangled compilers that requires them. Old code should still be
>>>> supported, though.
>>>>
>>>Last time I tried it, (about 2 months ago), the current GNU C compiler
>>>accepts the old K&R C first edition procedure declaration syntax. I wish
>>>more compilers worked this way.
>>
>> It will not, however, accept the original V6 C "a =+ b" ambiguous
>> syntax, so older code may still need to be edited before compilation
>> with a modern compiler.
>
>I don't *think* I've ever written that or even seen it in valid code.
>

From the V6 C compiler source:

        /*
         * The hash table locations of the keywords
         * are marked; if an identifier hashes to one of
         * these locations, it is looked up in in the keyword
         * table first.
         */
        for (ip=kwtab; (sp = ip->kwname); ip++) {
                i = 0;
                while (*sp)
                        i =+ *sp++;
                hshtab[i%hshsiz].hflag = FKEYW;
        }

Note also that in that version of the compiler, MOS
(member of structure) names were global and could be
used with any pointer regardless of type.

https://github.com/mortdeus/legacy-cc/blob/master/last1120c/c00.c

This makes it difficult to build the original V6 c compiler using
a modern compiler :-)

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