Bootstrap: update logic to support pre-and post python 3.8

[bkhouri]

PR #8373 (commit ID: 0193d5f) updated a shutil.copytree(...) command to pass in the dirs_exists_ok=True argument. However, Python added support for the dirs_exists_ok argument to shutil.copytree in 3.8.

Update the function call to inspect the python version, and only add the argument if the script is running in a Python version equal, or higher than 3.8.

• Python 3.7 documentation: https://docs.python.org/3.7/library/shutil.html#shutil.copytree
• Python 3.8 documentation: https://docs.python.org/3.8/library/shutil.html#shutil.copytree

rdar://147297864

[bkhouri]

@swift-ci please test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

@swift-ci please test

[bkhouri]

@swift-ci please test self hosted windows

[bkhouri]

@swift-ci test windows

[bnbarham]

The docs for 3.7 state that the destination must not already exist, which means this doesn't fix the problem the original PR was trying to solve here in that case.

[bkhouri]

@bnbarham : Right. If the builds fail, what are you thoughts about this ?

diff --git a/Utilities/bootstrap b/Utilities/bootstrap
index e87e21fae..89230385b 100755
--- a/Utilities/bootstrap
+++ b/Utilities/bootstrap
@@ -16,6 +16,7 @@
 from __future__ import print_function
 
 import argparse
+import fnmatch
 import json
 import logging
 import os
@@ -25,6 +26,8 @@ import re
 import shutil
 import subprocess
 import sys
+import typing as t
+
 from helpers import symlink_force, mkdir_p, call, call_output
 
 
@@ -574,7 +577,8 @@ def install_dylib(args, library_name, install_dir, module_names):
 
 # Helper function that installs a single built artifact to a particular directory. The source may be either a file or a directory.
 @log_entry_exit
-def install_binary(args, binary, destination, destination_is_directory=True, ignored_patterns=[], subpath=None):
+def install_binary(args, binary, destination, destination_is_directory=True, ignored_patterns: t.Optional[t.Iterable[str]]=None, subpath=None):
+    ignored_patterns = ignored_patterns or []
     if subpath:
         basepath = os.path.join(args.bin_dir, subpath)
     else:
@@ -592,8 +596,34 @@ def install_file(args, src, destination, destination_is_directory=True, ignored_
 
     logging.info("Installing %s to %s", src, dest)
     if os.path.isdir(src):
-        additional_kwargs = { "dirs_exist_ok": True } if sys.version_info.major >=3 and sys.version_info.minor >= 8 else {}
-        shutil.copytree(src, dest, ignore=shutil.ignore_patterns(*ignored_patterns), **additional_kwargs)
+        if sys.version_info.major >=3 and sys.version_info.minor >= 8:
+            shutil.copytree(src, dest, ignore=shutil.ignore_patterns(*ignored_patterns), dirs_exist_ok=True)
+        else:
+            # need to ensure dest will be created
+            # it's better to find an proper API for Pyth9on <=3.7, but I wasn't able to.
+
+            def copy_tree_ignore(source_dir, dest_dir, *, ignore_patterns):
+                """
+                Copies a directory tree from source to dest, ignoring files/dirs matching patterns.
+                """
+                if not os.path.exists(dest_dir):
+                    os.makedirs(dest_dir)
+
+                for item in os.listdir(source_dir):
+                    source_item_path = os.path.join(source_dir, item)
+                    dest_item_path = os.path.join(dest_dir, item)
+
+                    if any(fnmatch.fnmatch(item, pattern) for pattern in ignore_patterns):
+                        continue
+
+                    if os.path.isfile(source_item_path):
+                        with open(source_item_path, 'rb') as source_file, open(dest_item_path, 'wb') as dest_file:
+                            dest_file.write(source_file.read())
+                    elif os.path.isdir(source_item_path):
+                        copy_tree_ignore(source_item_path, dest_item_path, ignore_patterns)
+
+            copy_tree_ignore(src, dest, ignore_patterns=ignored_patterns)
+
     else:
         shutil.copy2(src, dest)

[bkhouri]

@swift-ci test

[bkhouri]

@swift-ci test self hosted windows

[bkhouri]

@swift-ci test windows

[bkhouri]

@owenv FYI