setup.py not picking up tkinter headers from non-system macOS Tcl and Tk frameworks

[tonybaloney]

BPO	39162
Nosy	@ned-deily, @tonybaloney
PRs	bpo-39162 fix a logic bug in the Tcl/Tk include scanner for macOS in setup.py #17753
Superseder	bpo-34956: _tkinter built on macOS 10.14 does not link to Tcl and Tk in /Library/Frameworks

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/ned-deily'
closed_at = <Date 2020-05-18.13:59:47.036>
created_at = <Date 2019-12-30.08:35:06.559>
labels = ['build', '3.9']
title = 'setup.py not picking up tkinter headers from non-system macOS Tcl and Tk frameworks'
updated_at = <Date 2020-05-18.13:59:47.035>
user = 'https://github.com/tonybaloney'

bugs.python.org fields:

activity = <Date 2020-05-18.13:59:47.035>
actor = 'ned.deily'
assignee = 'ned.deily'
closed = True
closed_date = <Date 2020-05-18.13:59:47.036>
closer = 'ned.deily'
components = ['Build']
creation = <Date 2019-12-30.08:35:06.559>
creator = 'anthonypjshaw'
dependencies = []
files = []
hgrepos = []
issue_num = 39162
keywords = ['patch']
message_count = 4.0
messages = ['359026', '359027', '359034', '369222']
nosy_count = 2.0
nosy_names = ['ned.deily', 'anthonypjshaw']
pr_nums = ['17753']
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '34956'
type = 'compile error'
url = 'https://bugs.python.org/issue39162'
versions = ['Python 3.9']

[tonybaloney]

./configure && make -j4 is returning:

Failed to build these modules:
_tkinter

I'm running macOS 10.15.2, with the SDK installed using xcode-select --install (no funny business)

/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Tk.framework/

xcrun --show-sdk-path
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk

If I debug setup.py, I can see it's eagerly returning the wrong path (/System)

On a REPL, if I do:
>>> import setup
>>> setup.macosx_sdk_root()
'/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk'

So the path is correct, but I can see in setup.py that detect_tkinter_darwin() will break inside the loop if /System/Library/Frameworks/Tk.framework/Versions/Current exists (which it does), but it doesn't contain the headers, it contains 3 directories:

Resources Tk _CodeSignature

I think detect_tkinter_darwin should be updated so that framework_dirs scans macosx_sdk_root first, but I don't know what other scenarios this might break.

I'd be happy to submit a patch for my scenario but it looks like this whole function needs tests so each platform change and scenario as they come up. There's loads of other issues on BPO related.

[tonybaloney]

I also can't see how this condition would ever match, since macosx_sdk_root() is not in the list being iterated upon,
https://github.com/python/cpython/blob/master/setup.py#L1774

[tonybaloney]

This comes down to a logic bug in detect_tkinter_darwin(), shown in https://github.com/python/cpython/pull/17753/files#r361956102

[ned-deily]

Thanks for the report and the PR. Yes, detect_tkinter_darwin() had a number of problems due mainly to how Apple has first deprecated and more recently removed the option to have header files installed in the running system. Plus some nasty quirks of how the Tcl and Tk frameworks are built make it difficult to use them without hacks for embedding while supporting Python build options. Your analysis was helpful. In the end, I tried to fix this and some more general problems in detect_tkinter_darwin() with PR 20171 for bpo-34956 which will be available in 3.9.0b1.