Re: [coreutils] coreutils-7.0 expr exposes long-standing bug in matlab startup script

[Pádraig Brady]

Eric Blake wrote:
> According to Pádraig Brady on 10/14/2008 3:47 AM:
>>> With native versions of expr, and expr from GNU coreutils prior to
>>> version 7.0, the expansion of lscmd usually begins "-rw-r--r--", but
>>> the leading hyphen does not cause the word to be treated as an option.
>> I think that was an unintended change introduced when adding getopt to expr:
>> http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=f65cafd67b33009d23f940968bbe7f9a08d6fe13
> 
> Unintended or not, getopt's side effect of complaining about unrecognized
> options is necessary for standard compliance (ie. all earlier versions of
> coreutils had a bug in this area), so we should not revert it.

Quoting the spec:

"Also note that this volume of IEEE Std 1003.1-2001 permits implementations to 
extend utilities.
The expr utility permits the integer arguments to be preceded with a unary 
minus. This means that
an integer argument could look like an option. Therefore, the conforming 
application must employ
the "--" construct of Guideline 10 of the Base Definitions volume of IEEE Std 
1003.1-2001,
Section 12.2, Utility Syntax Guidelines to protect its operands if there is any 
chance the
first operand might be a negative integer (or any string with a leading minus)."

Does the above mean expr must support -- or that apps must use --
I think it's the former, and this is what the expr code tries to do.
I.E. it does try to treat non options starting with - as part of the expression.
However it gets it wrong in the case of chained short args as seen here:


localhost:~/git/coreutils/src$ expr -oh : -oh
3
localhost:~/git/coreutils/src$ expr -- -oh : -oh
3
localhost:~/git/coreutils/src$ ./expr-new -oh : -oh
./expr: syntax error
localhost:~/git/coreutils/src$ ./expr-new -o : -o
2
localhost:~/git/coreutils/src$ ./expr-new -- -oh : -oh
3


cheers,
Pádraig.

p.s. why does expr need the --bignum option anyway?
Shouldn't we just use it by default if available.