Adapting Perl packages to GCC removal from Fedora 29 build root

[Petr Pisar]

It's a long time I sent a message here. And because your read my new message,
it means something is wrong. Here it is:

GCC won't be in the minimal build root
<https://fedoraproject.org/wiki/Changes/Remove_GCC_from_BuildRoot> since
Fedora 29. That affects Perl packages that executes gcc at build time
<https://ignatenkobrain.fedorapeople.org/gcc-removal-pkgs.txt>;.

Many of them use ExtUtils::CBuilder
<https://ignatenkobrain.fedorapeople.org/gcc-removal.txt> and thus Paul
proposed adding dependency on gcc to perl-ExtUtils-CBuilder
<https://bugzilla.redhat.com/show_bug.cgi?id=1547165> instead of adding it to
each of the affected spec file as C guidelines recommends
<https://fedoraproject.org/wiki/Packaging:C_and_C%2B%2B#BuildRequires_and_...;.

It's true that the only reason for ExtUils::CBuilder existence is to build
C code. Thus it is reasonable to require gcc from this package.

(ExtUils::CBuilder also supports C++ and I think it makes sense to require
both gcc and gcc-c++.)

But if perl-ExtUtils-CBuilder will require gcc, then all Module::Build driven
packages (403) will pull in gcc because current perl-Module-Build requires
it. In reality there is only 59 architecture specific packages that uses
Module::Build.

So it's tempting to remove the ExtUtils::CBuilder dependency from
perl-Module-Build. Can we do it?

"XS Extensions" section in Module::Build::Authoring reads:

    Modules which need to compile XS code should list "ExtUtils::CBuilder"
    as a "build_requires" element.

Contrary to that Module-Build requires ExtUtils::CBuilder in it's META data.
Thus I don't believe CPAN distribution authors or Fedora packagers do that.
And indeed Fedora has 36 Module::Build packages that are missing
ExtUtils::CBuilder build-dependency:

perl-Alien-ROOT
perl-Alien-wxWidgets
perl-Authen-DecHpwd
perl-Boost-Geometry-Utils
perl-Config-Augeas
perl-Crypt-MySQL
perl-Crypt-ScryptKDF
perl-Data-Pond
perl-Devel-GoFaster
perl-File-Map
perl-Hash-FieldHash
perl-HTML-Escape
perl-IO-Interface
perl-JavaScript-Minifier-XS
perl-Judy
perl-KinoSearch1
perl-Lexical-SealRequireHints
perl-Lexical-Var
perl-Lchown
perl-Lingua-Stem-Snowball
perl-Net-IDN-Encode
perl-Net-LibIDN2
perl-Params-Classify
perl-Params-Validate
perl-Parse-DMIDecode
perl-PerlIO-buffersize
perl-PerlIO-Layers
perl-RPM2
perl-Scalar-String
perl-SDL
perl-Socket-Netlink
perl-Text-Xslate
perl-Thread-SigMask
perl-Time-timegm
perl-Unicode-CaseFold
remctl

I think it makes sense to implement this change:

(1) Add gcc and gcc-c++ dependency to perl-ExtUtils-CBuilder.
(2) Replace ExtUtils::CBuilder hard dependency with a weak dependency at
    Recommends level in perl-Module-Build.
(3) Add ExtUtils::CBuilder build-time dependency to those 36 packages.
(4) Add gcc weak dependency at Recommends level to perl-ExtUtils-MakeMaker.
(4) Add gcc build dependency to rest (mostly ExtUtils::MakeMaker-driven) spec
    files where it is missing.

Do you agree? Do you have a different opinion? Do you have a better plan?

-- Petr