[Mesa-dev] [PATCH v2] configure.ac: Use POSIX word boundary regex.

[Michel Dänzer]

On 20/03/17 12:19 AM, Eric Engestrom wrote:
> On Sunday, 2017-03-19 13:44:30 +0000, Jan Beich wrote:
>> Vinson Lee <vlee at freedesktop.org> writes:
>>
>>> -        -e 's/[[[:space:]]]+-DNDEBUG\>//g' \
>>> -        -e 's/[[[:space:]]]+-D_GNU_SOURCE\>//g' \
>>> -        -e 's/[[[:space:]]]+-pedantic\>//g' \
>>> +        -e 's/[[[:space:]]]+-DNDEBUG[[[:space:]]]//g' \
>>> +        -e 's/[[[:space:]]]+-D_GNU_SOURCE[[[:space:]]]//g' \
>>> +        -e 's/[[[:space:]]]+-pedantic[[[:space:]]]//g' \
>>
>> If you always expect whitespace on both sides but trim it the RE
>> may not match with more than one occurence in sequence e.g.,
>>
>>  $ echo ' -D_GNU_SOURCE -DNDEBUG ' |
>>    sed -E -e 's/[[:space:]]+-DNDEBUG[[:space:]]//g' \
>>           -e 's/[[:space:]]+-D_GNU_SOURCE[[:space:]]//g'
>>    -D_GNU_SOURCE
>>
>> vs. (restore some whitespace)
>>
>>   $ echo ' -D_GNU_SOURCE -DNDEBUG ' |
>>     sed -E -e 's/[[:space:]]+-DNDEBUG[[:space:]]/ /g' \
>>            -e 's/[[:space:]]+-D_GNU_SOURCE[[:space:]]/ /g'
>>
> 
> Oh yes, very good point there!
> My r-b now stands with this fix applied :)
> 
> This will lead to a bunch of unnecessary whitespace in the middle, but
> I'm not sure I'd recommend addressing this:
> A simple 's/[[[:space:]]]+/ /g' at the end should trivially fix this,
> [...]

Another option would be to match the trailing whitespace as a
subexpression and add that back on the right hand side.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer