On OS X Mojave, it is possible to have Xcode installed but to have no directory /usr/include.

• The configure check from more system package checks #26286 finds zlib somewhere, but the Python build does not: Python reports that it has built without zlib support. Without zlib, pip will not build.

• gcc/gfortran needs the location of headers to be explicitly passed via --with-native-system-header-dir= option. (untested)

Upstream: Reported upstream. No feedback yet.

CC: @embray

Component: packages: standard

Author: Dima Pasechnik, Volker Braun

Branch: db50d09

Reviewer: Dima Pasechnik, Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/26899