Bug 1622963 - Require python 3.6 for the build system. r=firefox-build-system-reviewers,rstewart

Differential Revision: https://phabricator.services.mozilla.com/D77754

build/moz.configure/init.configure

@@ -236,7 +236,7 @@ shell = help_shell | shell
 # Python 3
 # ========
 
-option(env='PYTHON3', nargs=1, help='Python 3 interpreter (3.5 or later)')
+option(env='PYTHON3', nargs=1, help='Python 3 interpreter (3.6 or later)')
 
 
 @depends('PYTHON3', check_build_environment, mozconfig, '--help')
@@ -333,20 +333,20 @@ def virtualenv_python3(env_python, build_env, mozconfig, help):
                                   '(%s): %s' % (python, e))
     else:
         # Fall back to the search routine.
-        python, version = find_python3_executable(min_version='3.5.0')
+        python, version = find_python3_executable(min_version='3.6.0')
 
         # The API returns a bytes whereas everything in configure is unicode.
         if python:
             python = ensure_text(python)
 
     if not python:
-        raise FatalCheckError('Python 3.5 or newer is required to build. '
+        raise FatalCheckError('Python 3.6 or newer is required to build. '
                               'Ensure a `python3.x` executable is in your '
                               'PATH or define PYTHON3 to point to a Python '
-                              '3.5 executable.')
+                              '3.6 executable.')
 
-    if version < (3, 5, 0):
-        raise FatalCheckError('Python 3.5 or newer is required to build; '
+    if version < (3, 6, 0):
+        raise FatalCheckError('Python 3.6 or newer is required to build; '
                               '%s is Python %d.%d' % (python, version[0],
                                                       version[1]))
 

python/mozbuild/mozbuild/pythonutil.py

@@ -45,7 +45,7 @@ def python_executable_version(exe):
 def _find_python_executable(major):
     if major not in (2, 3):
         raise ValueError('Expected a Python major version of 2 or 3')
-    min_versions = {2: '2.7.0', 3: '3.5.0'}
+    min_versions = {2: '2.7.0', 3: '3.6.0'}
 
     def ret(min_version=min_versions[major]):
         from mozfile import which

python/mozbuild/mozbuild/virtualenv.py

@@ -686,7 +686,7 @@ def verify_python_version(log_handle):
 
     major, minor, micro = sys.version_info[:3]
     minimum_python_version = (
-        LooseVersion('3.5.0') if major == 3 else LooseVersion('2.7.3'))
+        LooseVersion('3.6.0') if major == 3 else LooseVersion('2.7.3'))
     our = LooseVersion('%d.%d.%d' % (major, minor, micro))
 
     if major not in (2, 3) or our < minimum_python_version: