Feature #10728: Warning for Fixnum#size to use RbConfig::SIZEOF['long']

• Status: Open
• Assignee: -
• Target version: -

[akr (Akira Tanaka)]

How about add a warning for Fixnum#size ?

% ./ruby -e 'p 0.size'
-e:1: warning: Use RbConfig::SIZEOF['long'] instead of Fixnum#size
8

Currently it returns sizeof(long) which is 4 or 8.

However it is implementation detail and
it may difficult to define it in Ruby implementations other than CRuby.

There is a way to obtain sizeof(long): RbConfig::SIZEOF['long']
It works since Ruby 2.1.

% ruby -rrbconfig/sizeof -e "p RbConfig::SIZEOF['long']"    
8

So the warning is a migration path to use RbConfig::SIZEOF['long'].

Note that this may affect many code.
So this issue may irritate many people.
fixnum-size-search.txt is a search result in gems.

[cremno (cremno phobia)]

I took a look at fixnum-size-search.txt and using RbConfig::SIZEOF['long'] instead usually isn't the correct replacement. In many lines the size of long in bytes isn't of interest, the min- and maximum value of a fixnum is (see feature request #7517).

[akr (Akira Tanaka)]

• Related to Feature #7517: Fixnum::MIN,MAX added

[akr (Akira Tanaka)]

RbConfig::SIZEOF['long'] is a drop-in replacement but Fixnum::MAX is not.

Also, I feel Fixnum is a implementation detail.