CPAN->deb related fixes (jordansissel#1947)

* fix comment at end of cpan class

* make &perldepfix create correct dependencies for cpan->deb packages

prior version created automatic dependencies for deb packages that
weren't named according to the standard specified here:
https://www.debian.org/doc/packaging-manuals/perl-policy/ch-module_packages.html

* add --cpan-package-name-postfix and fix automatic names cpan pkgs

use --cpan-package-name-prefix and --cpan-package-name-postfix to
create the cpan package name

do not assume a dash between the prefix and the package name

change the defualt prefix from perl to perl- because for deb packages
you want the prefix to be lib and do not want a -

* add --cpan-package-reject-from-depends option to filter auto-depends

The auto-depends for cpan modules worked well on rpm because of the
use of capabilities (ie: perl(IO::Handle)) but deb packages of CPAN
modules generate dependencies that might not exist because they are
provided by another package and therefore need to be filtered out.

For instance, perl(IO::Handle) would be turned into libio-handle-perl,
and that package doesn't exist.  The IO/Handle.pm file is actually in
package perl-base.

Prior to this patch, fpm would filter out a short list of
modules (vars, warnings, strict, and Config) and with this patch you
can add to that list with --cpan-package-reject-from-depends.

* update getting-started.rst to reflect cpan related changes

* Revert "update getting-started.rst to reflect cpan related changes"

This reverts commit ae1a628.

* Revert "add --cpan-package-reject-from-depends option to filter auto-depends"

This reverts commit b4e138f.

* Revert "add --cpan-package-name-postfix and fix automatic names cpan pkgs"

This reverts commit 1564cd9.

* add --cpan-package-reject-from-depends option to filter auto-depends

The auto-depends for cpan modules worked well on rpm because of the
use of capabilities (ie: perl(IO::Handle)) but deb packages of CPAN
modules generate dependencies that might not exist because they are
provided by another package and therefore need to be filtered out.

For instance, perl(IO::Handle) would be turned into libio-handle-perl,
and that package doesn't exist.  The IO/Handle.pm file is actually in
package perl-base.

Prior to this patch, fpm would filter out a short list of
modules (vars, warnings, strict, and Config) and with this patch you
can add to that list with --cpan-package-reject-from-depends.

* use Debian style names for CPAN modules

---------

Co-authored-by: Aran Cox <aran-cox@uiowa.edu>
Co-authored-by: Jordan Sissel <131818+jordansissel@users.noreply.github.com>

Author: 3 people

lib/fpm/package/cpan.rb

@@ -22,6 +22,13 @@ class FPM::Package::CPAN < FPM::Package
   option "--package-name-prefix", "NAME_PREFIX",
     "Name to prefix the package name with.", :default => "perl"
 
+  option "--package-reject-from-depends", "MODULE",
+    "Filter modules matching MODULE from those generated by " \
+    "the auto-depends for CPAN modules. This flag can be specified " \
+    "multiple times. Use the perl module name, IE: URI::Escape.",
+    :multivalued => true, :attribute_name => :rejects,
+    :default => ['vars','warnings','strict','Config']
+
   option "--test", :flag,
     "Run the tests before packaging?", :default => true
 

lib/fpm/package/deb.rb

@@ -787,10 +787,19 @@ def converted_from(origin)
     self.provides = self.provides.reject { |p| p.empty? }
 
     if origin == FPM::Package::CPAN
+
+      # By default, we'd prefer to name Debian-targeted Perl packages using the
+      # same naming scheme that Debian itself uses, which is usually something
+      # like "lib<module-name-hyphenated>-perl", such as libregexp-common-perl
+      #
+      logger.info("Changing package name to match Debian's typical libmodule-name-perl style")
+      self.name = "lib#{self.name.sub(/^perl-/, "")}-perl"
+
       # The fpm cpan code presents dependencies and provides fields as perl(ModuleName)
       # so we'll need to convert them to something debian supports.
 
-      # Replace perl(ModuleName) > 1.0 with Debian-style perl-ModuleName (> 1.0)
+      # Replace perl(Module::Name) > 1.0 with Debian-style libmodule-name-perl (> 1.0)
+      # per: https://www.debian.org/doc/packaging-manuals/perl-policy/ch-module_packages.html
       perldepfix = lambda do |dep|
         m = dep.match(/perl\((?<name>[A-Za-z0-9_:]+)\)\s*(?<op>.*$)/)
         if m.nil?
@@ -801,7 +810,7 @@ def converted_from(origin)
           modulename = m["name"].gsub("::", "-")
 
           # Fix any upper-casing or other naming concerns Debian has about packages
-          name = "#{attributes[:cpan_package_name_prefix]}-#{modulename}"
+          name = "lib#{modulename}-perl"
 
           if m["op"].empty?
             name
@@ -812,7 +821,9 @@ def converted_from(origin)
         end
       end
 
-      rejects = [ "perl(vars)", "perl(warnings)", "perl(strict)", "perl(Config)" ]
+      rejects = attributes[:rejects].map do |skip|
+        "perl(#{skip})"
+      end
       self.dependencies = self.dependencies.reject do |dep|
         # Reject non-module Perl dependencies like 'vars' and 'warnings'
         rejects.include?(dep)