split bitwise-assignment operators (`&=`, `&.=`, etc) don't return lvalues

[mauke]

Description Assignment operators (like = itself, but also += or >>=) are supposed to return their left operand as an lvalue, which can then be further modified within the same expression. The old combined numeric/string bitwise assignment operators do this, but the new(er) split numeric and string bitwise operators (as provided by use feature qw(bitwise)) do not.

Steps to Reproduce

$ perl -wle '$_ = 1; ($_ |= 9) ^= 4; print'
13
$ perl -wle '$_ = "HI"; ($_ |= "") ^= " " x 2; print'
hi
$ perl -wle 'use feature qw(bitwise); $_ = 1; ($_ |= 9) ^= 4; print'
Can't modify numeric bitwise or (|) in numeric bitwise xor (^) at -e line 1, near "4;"
Execution of -e aborted due to compilation errors.
$ perl -wle 'use feature qw(bitwise); $_ = "HI"; ($_ |.= "") ^.= " " x 2; print'
Can't modify string bitwise or (|.) in string bitwise xor (^.) at -e line 1, near "2;"
Execution of -e aborted due to compilation errors.

Expected behavior

$ perl -wle '$_ = 1; ($_ |= 9) ^= 4; print'
13
$ perl -wle '$_ = "HI"; ($_ |= "") ^= " " x 2; print'
hi
$ perl -wle 'use feature qw(bitwise); $_ = 1; ($_ |= 9) ^= 4; print'
13
$ perl -wle 'use feature qw(bitwise); $_ = "HI"; ($_ |.= "") ^.= " " x 2; print'
hi

v5.40.0

[sisyphus]

Heh ... the same behaviour apparently permeates through to the overloading of these operators. Perhaps that's an obvious ramification that didn't need to be pointed out. (I don't know.)

D:\>perl -MMath::BigInt -wle "$x = Math::BigInt->new(64); ($x &= 3) |= 2; print $x;"
2

D:\>perl -MMath::BigInt -wle "use feature qw(bitwise); $x = Math::BigInt->new(64); ($x &= 3) |= 2; print $x;"
Can't modify numeric bitwise and (&) in numeric bitwise or (|) at -e line 1, near "2;"
Execution of -e aborted due to compilation errors.