class :isa does not require parent class with hierarchical naming

[ntyni]

This is a bug report for perl from [email protected],
generated with the help of perlbug 1.43 running under perl 5.39.2.

---

Description

If the class A::B inherits A with 'class A::B :isa(A)', A.pm does not
get loaded/required. This seems to be because of the hierarchical naming:
class B :isa(A) loads A.pm just fine.

I don't see a mention of this in the documentation, and Object::Pad
does not exhibit the same behaviour FWIW.

Explicitly loading A first (with e.g. 'use A') seems to be a workaround.

Steps to Reproduce

% cat lib/A.pm
use feature 'class';
class A {};
1;
% cat lib/A/B.pm
use feature 'class';
class A::B :isa(A) {};
1;
% perl -Ilib -c lib/A/B.pm; echo $?
class is experimental at lib/A/B.pm line 2.
Class :isa attribute requires a class but "A" is not one at lib/A/B.pm line 2.
255

Expected behavior
A.pm should get loaded as described in perlclass.pod for :isa().

---

Flags

• category=core
• severity=low

---

Perl configuration

Site configuration information for perl 5.39.2:

Configured by ntyni at Mon Aug	7 18:05:37 BST 2023.

Summary of my perl5 (revision 5 version 39 subversion 2) configuration:
  Commit id: 4f06424962ba637e7daad1d020cdd9573a9acdda
  Platform:
    osname=linux
    osvers=6.1.0-3-amd64
    archname=x86_64-linux
    uname='linux carme 6.1.0-3-amd64 #1 smp preempt_dynamic debian 6.1.8-1 (2023-01-29) x86_64 gnulinux '
    config_args='-des -Dusedevel'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=undef
    usemultiplicity=undef
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
  Compiler:
    cc='cc'
    ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
    optimize='-O2'
    cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='12.2.0'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='cc'
    ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/x86_64-linux-gnu /usr/lib /usr/lib64
    libs=-lpthread -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
    perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc
    libc=/lib/x86_64-linux-gnu/libc.so.6
    so=so
    useshrplib=false
    libperl=libperl.a
    gnulibc_version='2.36'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E'
    cccdlflags='-fPIC'
    lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'


---
@INC for perl 5.39.2:
    lib
    /usr/local/lib/perl5/site_perl/5.39.2/x86_64-linux
    /usr/local/lib/perl5/site_perl/5.39.2
    /usr/local/lib/perl5/5.39.2/x86_64-linux
    /usr/local/lib/perl5/5.39.2

---
Environment for perl 5.39.2:
    HOME=/home/ntyni
    LANG=C
    LANGUAGE (unset)
    LC_CTYPE=fi_FI.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/bin:/bin:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/zsh