fix: error out if multiple wheels with the same name are produced

We shouldn't silently overwrite wheels that are produced in the same run that have the same filename, as this implies a misconfiguration.

cibuildwheel/linux.py

@@ -10,6 +10,7 @@ from .logger import log
 from .options import Options
 from .typing import OrderedDict, PathOrStr, assert_never
 from .util import (
+    AlreadyBuiltWheelError,
     BuildSelector,
     NonPlatformWheelError,
     find_compatible_wheel,
@@ -255,6 +256,10 @@ def build_on_docker(
 
             repaired_wheels = docker.glob(repaired_wheel_dir, "*.whl")
 
+            for repaired_wheel in repaired_wheels:
+                if repaired_wheel.name in {wheel.name for wheel in built_wheels}:
+                    raise AlreadyBuiltWheelError(repaired_wheel.name)
+
         if build_options.test_command and build_options.test_selector(config.identifier):
             log.step("Testing wheel...")
 

cibuildwheel/macos.py

@@ -17,6 +17,7 @@ from .options import Options
 from .typing import Literal, PathOrStr, assert_never
 from .util import (
     CIBW_CACHE_PATH,
+    AlreadyBuiltWheelError,
     BuildFrontend,
     BuildSelector,
     NonPlatformWheelError,
@@ -408,6 +409,9 @@ def build(options: Options, tmp_path: Path) -> None:
 
                 repaired_wheel = next(repaired_wheel_dir.glob("*.whl"))
 
+                if repaired_wheel.name in {wheel.name for wheel in built_wheels}:
+                    raise AlreadyBuiltWheelError(repaired_wheel.name)
+
                 log.step_end()
 
             if build_options.test_command and build_options.test_selector(config.identifier):

cibuildwheel/util.py

@@ -373,6 +373,20 @@ class NonPlatformWheelError(Exception):
         super().__init__(message)
 
 
+class AlreadyBuiltWheelError(Exception):
+    def __init__(self, wheel_name: str) -> None:
+        message = textwrap.dedent(
+            f"""
+            cibuildwheel: Build failed because a wheel named {wheel_name} was already generated in the current run.
+
+            If you expected another wheel to be generated, check your project configuration, or run
+            cibuildwheel with CIBW_BUILD_VERBOSITY=1 to view build logs.
+            """
+        )
+
+        super().__init__(message)
+
+
 def strtobool(val: str) -> bool:
     return val.lower() in {"y", "yes", "t", "true", "on", "1"}
 

cibuildwheel/windows.py

@@ -17,6 +17,7 @@ from .options import Options
 from .typing import PathOrStr, assert_never
 from .util import (
     CIBW_CACHE_PATH,
+    AlreadyBuiltWheelError,
     BuildFrontend,
     BuildSelector,
     NonPlatformWheelError,
@@ -365,6 +366,9 @@ def build(options: Options, tmp_path: Path) -> None:
 
                 repaired_wheel = next(repaired_wheel_dir.glob("*.whl"))
 
+                if repaired_wheel.name in {wheel.name for wheel in built_wheels}:
+                    raise AlreadyBuiltWheelError(repaired_wheel.name)
+
             if build_options.test_command and options.globals.test_selector(config.identifier):
                 log.step("Testing wheel...")
                 # set up a virtual environment to install and test from, to make sure

test/test_same_wheel.py

@@ -0,0 +1,42 @@
+import subprocess
+from test import test_projects
+
+import pytest
+
+from . import utils
+
+basic_project = test_projects.new_c_project()
+basic_project.files[
+    "repair.py"
+] = """
+import shutil
+import sys
+from pathlib import Path
+
+wheel = Path(sys.argv[1])
+dest_dir = Path(sys.argv[2])
+platform = wheel.stem.split("-")[-1]
+name = f"spam-0.1.0-py2-none-{platform}.whl"
+dest = dest_dir / name
+dest_dir.mkdir(parents=True, exist_ok=True)
+if dest.exists():
+    dest.unlink()
+shutil.copy(wheel, dest)
+"""
+
+
+def test(tmp_path, capfd):
+    # this test checks that a generated wheel name shall be unique in a given cibuildwheel run
+    project_dir = tmp_path / "project"
+    basic_project.generate(project_dir)
+
+    with pytest.raises(subprocess.CalledProcessError):
+        utils.cibuildwheel_run(
+            project_dir,
+            add_env={
+                "CIBW_REPAIR_WHEEL_COMMAND": "python repair.py {wheel} {dest_dir}",
+            },
+        )
+
+    captured = capfd.readouterr()
+    assert "Build failed because a wheel named" in captured.err