Feature #19344
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Regexp.new: stricter handling of second argument
Description
Since Ruby 3.2 (#18788), the second argument to Regexp.new can be:
- Integer: then it is treated as a combination of
Regexp::<constant>flags - String: then it is treated as a combination of string flags
-
nilorfalse: then it is ignored - any other truthy value: then it is treated as an "ignore case" option.
The fourth one is confusing, especially since the introduction of the flexibility of flags: one might erroneously assume or forget the protocol, and the naive check will strengthen the assumption:
# maybe it accepts the array of string options?..
Regexp.new('foo', %w[i]) #=> /foo/i -- oh, seems it does
# would the symbol work?..
Regexp.new('foo', :i) #=> /foo/i -- awesome, it works!
I propose to change (4) to only handle literal true value, and raise TypeError on any unsupported type.
On compatibility: I believe that whenever the usage of boolean to distinguish "ignore case/respect case" is deliberate (like in rubygems), the code already passes true/false, not any random value. Otherwise, the change in Ruby 3.2 might also have broken it (what if it previously passed strings, meaning them to be "truthy values"?)
PS: BTW, the documentation for (4) was completely lost in Ruby 3.2, due to this PR. cc @jeremyevans0 (Jeremy Evans), @burdettelamar (Burdette Lamar)
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