Don't warn on false positive for author/maintainer's email

While I was working to support pyproject.toml metadata in setuptools,
I received as a feedback from the community[^1] that setuptools
warns the following message when `author_email` and `maintainer_email`
are given in the form of `Person Name <email@address>`:

> warning: check: missing meta-data: either (author and author_email)
> or (maintainer and maintainer_email) should be supplied

This can be seen as a false positive, because indeed both author's name
and email are provided.

This warning seems to happen because distutils define the `check`
command as a subcommand for `sdist`.

This change aims to remove this false positive result from the checks.

[^1]: https://discuss.python.org/t/help-testing-experimental-features-in-setuptools/13821/18

1 files changed, 31 insertions, 9 deletions

diff --git a/distutils/command/check.py b/distutils/command/check.py
index 525540b6..af311ca9 100644
--- a/distutils/command/check.py
+++ b/distutils/command/check.py
@@ -2,6 +2,8 @@
 
 Implements the Distutils 'check' command.
 """
+from email.utils import getaddresses
+
 from distutils.core import Command
 from distutils.errors import DistutilsSetupError
 
@@ -96,19 +98,39 @@ class check(Command):
 
         if missing:
             self.warn("missing required meta-data: %s"  % ', '.join(missing))
-        if metadata.author:
-            if not metadata.author_email:
-                self.warn("missing meta-data: if 'author' supplied, " +
-                          "'author_email' should be supplied too")
-        elif metadata.maintainer:
-            if not metadata.maintainer_email:
-                self.warn("missing meta-data: if 'maintainer' supplied, " +
-                          "'maintainer_email' should be supplied too")
-        else:
+        if not (
+            self._check_contact("author", metadata) or
+            self._check_contact("maintainer", metadata)
+        ):
             self.warn("missing meta-data: either (author and author_email) " +
                       "or (maintainer and maintainer_email) " +
                       "should be supplied")
 
+    def _check_contact(self, kind, metadata):
+        """
+        Returns True if the contact's name is specified and False otherwise.
+        This function will warn if the contact's email is not specified.
+        """
+        name = getattr(metadata, kind) or ''
+        email = getattr(metadata, kind + '_email') or ''
+
+        msg = ("missing meta-data: if '{}' supplied, " +
+               "'{}' should be supplied too")
+
+        if name and email:
+            return True
+
+        if name:
+            self.warn(msg.format(kind, kind + '_email'))
+            return True
+
+        addresses = [(alias, addr) for alias, addr in getaddresses([email])]
+        if any(alias and addr for alias, addr in addresses):
+            # The contact's name can be encoded in the email: `Name <email>`
+            return True
+
+        return False
+
     def check_restructuredtext(self):
         """Checks if the long string fields are reST-compliant."""
         data = self.distribution.get_long_description()