Re: [Tinycc-devel] Small curiosity, re operator precedence.

[Paulo Henrique Torrens]

This is a "feature". Ansi C says that the post and preincrements order are 
implementation defined. As it seems, there is something about the precedence 
order of the ==, that problably is some optimization. In order to achieve 
portability, separe it in some lines with the right order. But, yeah, that's no 
bug. :)

-----Original Message-----

From: Lostgallifreyan
Sent: 12 Apr 2012 13:15:19 GMT
To: address@hidden
Subject: Re: [Tinycc-devel] Small curiosity, re operator precedence.


Lostgallifreyan <address@hidden> wrote:
(31/03/2012 09:47)

>Please ignore any 'unsafe' aspect this example might have, it IS bounded in 
>the context I'm using it in....
>
>while((*--o=*--i)!=92)
>
>I was tryign to reduce stuff, so came up with this to try:
>
>while(92!=*--o=*--i)
>
>TCC loves it, GCC hates it. :)
>
>GCC thinks it's doing this: while((92!=*--o)=*--i) and therefore an invalid 
>lvalue, which makes sense given what Wikipedia has to say about precedence, 
>but TCC (still using v0.9.24 here) seems to do what I was wondering if it 
>might do, to compare the dereferenced value when it is copied. I reverted to 
>the original form because the more compilers take my code the happier I am 
>about it, but I'm interested. Is this a bug, or a feature? :)
>


Rudolph Loew, maker of the 48 bit LBA patch for W98, amongst other things, says 
this:

It does appear to be a bug as far as I can tell.
They should not be reinterpreting the precedence even if the intent can be 
inferred.


I'm losing my limited power to code, I think my brain is dying. Not kidding. 
Not a coding problem so I'll say no more about it other than this: I cannot be 
trusted to fix the code, even if I try, especially as I don't know enough about 
TCC, and this needs to be looked at by someone working on TCC! You have a 
choice of two base assumptions: Rudolph Loew's brain is also dying, or there is 
a problem you need to check out.


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