pw_build: Error out when copying two .whl with the same name

collect_wheels.py is used by the "pw_python_wheels" template to collect
all the .whl files from a series of directories and copy them to a
single output directory. The source directories could have .whl files
with the same name in different directories, but there can only be one
of those in the output directory.

This patch makes collect_wheels.py fail when trying to copy two files
with the same name.

Change-Id: Ia0464711c86257fe8bca2195186473426b1754f2
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/110651
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Alex Deymo <deymo@google.com>

pw_build/py/pw_build/collect_wheels.py

@@ -18,6 +18,7 @@
 from pathlib import Path
 import shutil
 import sys
+from typing import Dict
 
 _LOG = logging.getLogger(__name__)
 
@@ -45,12 +46,20 @@ def copy_wheels(prefix, suffix_file, out_dir):
     if not out_dir.exists():
         out_dir.mkdir()
 
+    copied_files: Dict[str, Path] = dict()
     for suffix in suffix_file.readlines():
         path = prefix / suffix.strip()
         _LOG.debug('Searching for wheels in %s', path)
         if path == out_dir:
             continue
         for wheel in path.glob('**/*.whl'):
+            if wheel.name in copied_files:
+                _LOG.error('Attempting to override %s with %s',
+                           copied_files[wheel.name], wheel)
+                raise FileExistsError(
+                    f'{wheel.name} conflict: '
+                    f'{copied_files[wheel.name]} and {wheel}')
+            copied_files[wheel.name] = wheel
             _LOG.debug('Copying %s to %s', wheel, out_dir)
             shutil.copy(wheel, out_dir)