Re: [PATCH] Let '^' through the lexer

[Jan Beulich <jbeulich@suse.com>]

On 13.07.2023 01:02, Alan Modra via Binutils wrote:
> On Wed, Jul 12, 2023 at 01:56:54PM +0000, Michael Matz via Binutils wrote:
>> so that the (existing) code in parser and expression evaluator
>> actually get to see it and handle it as XOR.
>> ---
>>
>> A colleague was asking me about why XOR is missing from linker scripts and 
>> I initially wanted to say "but it is supported, only undocumented", 
>> because I distinctly remembered the code handling XOR in the expression 
>> parser and evaluator.  But ... he was right.  The lexer unhelpfully 
>> doesn't let '^' through and just spits out a "unrecognized character" 
>> error.
>>
>> This is the case since the dawn of time it seems (ldgram end ldexp 
>> handling it, but ldlex not), but I don't see a reason.  While '^' 
>> might also be a meta-character in other lexer modes, that's no different 
>> from, say, '?' and '*'.  So, let's just handle it as well, document it, 
>> and leave it be :-)
>>
>> (I have looked around for a testcase that systematically tests the 
>> expression syntax in linker scripts.  I can't find one, so I haven't added 
>> a case for this one either).
>>
>> This is regtested on x86-64-linux only, my test-everything setup is 
>> missing right now.  Assuming that that works as well, okay for master?
> 
> OK, but..
> 
>> --- a/ld/ld.texi
>> +++ b/ld/ld.texi
>> @@ -6826,11 +6826,12 @@ precedence      associativity   Operators                Notes
>>  4               left            >>  <<
>>  5               left            ==  !=  >  <  <=  >=
> 
> Since you're adjusting this table, can you fix the precedence above?
> == and != are lower precedence than the other relational operators.
> 
>>  6               left            &
>> -7               left            |
>> -8               left            &&
>> -9               left            ||
>> -10              right           ? :
>> -11              right           &=  +=  -=  *=  /=       (2)
>> +7               left            ^
>> +8               left            |
>> +9               left            &&
>> +10              left            ||
>> +11              right           ? :
>> +12              right           &=  +=  -=  *=  /=       (2)
> 
> This line misses some assignment operators supported by ldgram.y.
> It should be += -= *= /= <<= >>= &= |=

At which point, considering the subject of the patch, I'm inclined
to ask: What about ^=?

Jan