builtin::reftype string comparison provides incorrect warning

[mbeijen]

Steps to Reproduce
Please note how builtin::reftype reports that the scalar $i is uninitialized, where it is not! Scalar::Util::reftypes error message is correct.

$ perl -Mv5.35 -MScalar::Util -E 'my $i = 1; builtin::reftype($i) eq "HASH"; Scalar::Util::reftype($i) eq "HASH"'
..
Use of uninitialized value $i in string eq at -e line 1.
Use of uninitialized value in string eq at -e line 1.

Expected behavior
I would expect the same warning as provided by Scalar::Reftype.

Perl configuration
Standard blead on x64 linux.

[jkeenan]

Steps to Reproduce Please note how builtin::reftype reports that the scalar $i is uninitialized, where it is not! Scalar::Util::reftypes error message is correct.

$ perl -Mv5.35 -MScalar::Util -E 'my $i = 1; builtin::reftype($i) eq "HASH"; Scalar::Util::reftype($i) eq "HASH"'
..
Use of uninitialized value $i in string eq at -e line 1.
Use of uninitialized value in string eq at -e line 1.

Expected behavior I would expect the same warning as provided by Scalar::Reftype.
[snip]

With a perl built at the v5.35.6 tag, I get different results from you.

$ ./bin/perl -Ilib -v | head -2 | tail -1
This is perl 5, version 35, subversion 6 (v5.35.6) built for amd64-freebsd-thread-multi

$ ./bin/perl -Ilib -MScalar::Util -E 'my $i = 1; builtin::reftype($i) eq "HASH"; Scalar::Util::reftype($i) eq "HASH";'
Undefined subroutine &builtin::reftype called at -e line 1.

Invoking the same command, but requesting warnings, I get:

$ ./bin/perl -Ilib -MScalar::Util -wE 'my $i = 1; builtin::reftype($i) eq "HASH";
Scalar::Util::reftype($i) eq "HASH";'
Useless use of string eq in void context at -e line 1.
Useless use of string eq in void context at -e line 1.
Undefined subroutine &builtin::reftype called at -e line 1.

I get the same output as above when I substitute -Mwarnings for -w.

[haarg]

builtin::reftype does not exist in v5.35.6, only in blead.