bump minimum required version of python to 3.7

Comment out the pending deprecation notice. It cannot be reached
anymore, but is still useful for the next time we do a version bump.

README.md

@@ -14,7 +14,7 @@ build system.
 
 #### Dependencies
 
- - [Python](https://python.org) (version 3.6 or newer)
+ - [Python](https://python.org) (version 3.7 or newer)
  - [Ninja](https://ninja-build.org) (version 1.8.2 or newer)
 
 #### Installing from source

azure-pipelines.yml

@@ -62,7 +62,7 @@ jobs:
   steps:
   - task: UsePythonVersion@0
     inputs:
-      versionSpec: '3.6'
+      versionSpec: '3.7'
       addToPath: true
       architecture: 'x64'
   - task: PowerShell@2

ci/run.ps1

@@ -20,7 +20,7 @@ if ($env:arch -eq 'x64') {
     # Rust puts its shared stdlib in a secret place, but it is needed to run tests.
     $env:Path += ";$HOME/.rustup/toolchains/stable-i686-pc-windows-msvc/bin"
     # Need 32-bit Python for tests that need the Python dependency
-    $env:Path = "C:\hostedtoolcache\windows\Python\3.6.8\x86;C:\hostedtoolcache\windows\Python\3.6.8\x86\Scripts;$env:Path"
+    $env:Path = "C:\hostedtoolcache\windows\Python\3.7.9\x86;C:\hostedtoolcache\windows\Python\3.7.9\x86\Scripts;$env:Path"
 }
 
 # Set the CI env var for the meson test framework

docs/markdown/Getting-meson.md

@@ -1,6 +1,6 @@
 # Getting Meson
 
-Meson is implemented in Python 3, and requires 3.6 or newer. If your
+Meson is implemented in Python 3, and requires 3.7 or newer. If your
 operating system provides a package manager, you should install it
 with that. For platforms that don't have a package manager, you need
 to download it from [Python's home page]. See below for
@@ -14,7 +14,7 @@ itself without doing anything special.
 
 On Windows, if you did not install Python with the installer options
 that make Python scripts executable, you will have to run `python
-/path/to/meson.py`, where `python` is Python 3.6 or newer.
+/path/to/meson.py`, where `python` is Python 3.7 or newer.
 
 The newest development code can be obtained directly from [Git], and
 we strive to ensure that it will always be working and usable. All

docs/markdown/Getting-meson_ptbr.md

@@ -1,6 +1,6 @@
 # Obtendo o Meson
 
-Meson é implementado em Python 3, e requer a versão 3.6 ou mais nova.
+Meson é implementado em Python 3, e requer a versão 3.7 ou mais nova.
 se o seu sistema operacional provê um gerenciador de pacotes, você deve
 instalar o Meson com ele. Para plataformas que não tem um gerenciador de
 pacotes, você precisa baixa-lo da [página inicial do Python]. Veja abaixo
@@ -14,7 +14,7 @@ do git sem fazer nada de especial.
 
 No Windows, se você não instalar o Python com a opção do instalador que fazem
 os *scripts* Python executáveis, você vai ter que executar `python
-/path/to/meson.py`, onde `python` é o Python 3.6 ou mais novo.
+/path/to/meson.py`, onde `python` é o Python 3.7 ou mais novo.
 
 O código de desenvolvimento mais recente pode ser obtido diretamente do [Git],
 e nós lutamos para garatir que ele vai estar sempre funcionando e usável. Todos

docs/markdown/snippets/about_minimum_python_version.md

@@ -0,0 +1,7 @@
+## Minimum required Python version updated to 3.7
+
+Meson now requires at least Python version 3.7 to run as Python 3.6 reached EOL
+on December 2021. In practice this should only affect people developing on
+Ubuntu Bionic, who will need to manually install python3.8 from the official
+repositories.
+

mesonbuild/mesonmain.py

@@ -139,6 +139,9 @@ class CommandLineParser:
         if command is None:
             command = options.command
 
+        # Bump the version here in order to add a pre-exit warning that we are phasing out
+        # support for old python. If this is already the oldest supported version, then
+        # this can never be true and does nothing.
         if command in ('setup', 'compile', 'test', 'install') and sys.version_info < (3, 7):
             pending_python_deprecation_notice = True
 
@@ -204,8 +207,8 @@ def ensure_stdout_accepts_unicode():
                 sys.stdout.buffer = sys.stdout.raw if hasattr(sys.stdout, 'raw') else sys.stdout
 
 def run(original_args, mainfile):
-    if sys.version_info < (3, 6):
-        print('Meson works correctly only with python 3.6+.')
+    if sys.version_info < (3, 7):
+        print('Meson works correctly only with python 3.7+.')
         print(f'You have python {sys.version}.')
         print('Please update your environment')
         return 1

setup.cfg

@@ -23,7 +23,6 @@ classifiers =
   Operating System :: POSIX :: BSD
   Operating System :: POSIX :: Linux
   Programming Language :: Python :: 3 :: Only
-  Programming Language :: Python :: 3.6
   Programming Language :: Python :: 3.7
   Programming Language :: Python :: 3.8
   Programming Language :: Python :: 3.9
@@ -32,7 +31,7 @@ long_description = Meson is a cross-platform build system designed to be both as
 
 [options]
 packages = find:
-python_requires = >= 3.6
+python_requires = >= 3.7
 setup_requires =
   setuptools
 

setup.py

@@ -16,9 +16,9 @@
 
 import sys
 
-if sys.version_info < (3, 6):
+if sys.version_info < (3, 7):
     raise SystemExit('ERROR: Tried to install Meson with an unsupported Python version: \n{}'
-                     '\nMeson requires Python 3.6.0 or greater'.format(sys.version))
+                     '\nMeson requires Python 3.7.0 or greater'.format(sys.version))
 
 from setuptools import setup