Replace sys.exit in conda_build.build.bundle_conda (#5367)

conda_build/build.py

@@ -1753,13 +1753,16 @@ def bundle_conda(
                     output["script"],
                     args[0],
                 )
-            if "system32" in args[0] and "bash" in args[0]:
-                print(
-                    "ERROR :: WSL bash.exe detected, this will not work (PRs welcome!). Please\n"
-                    "         use MSYS2 packages. Add `m2-base` and more (depending on what your"
-                    "         script needs) to `requirements/build` instead."
+            if (
+                # WSL bash is always the same path, it is an alias to the default
+                # distribution as configured by the user
+                on_win and Path("C:\\Windows\\System32\\bash.exe").samefile(args[0])
+            ):
+                raise CondaBuildUserError(
+                    "WSL bash.exe is not supported. Please use MSYS2 packages. Add "
+                    "`m2-base` and more (depending on what your script needs) to "
+                    "`requirements/build` instead."
                 )
-                sys.exit(1)
         else:
             args = interpreter.split(" ")
 

tests/test_build.py

@@ -15,13 +15,16 @@
 from typing import TYPE_CHECKING
 
 import pytest
+from conda.common.compat import on_win
 
 from conda_build import api, build
 from conda_build.exceptions import CondaBuildUserError
 
 from .utils import get_noarch_python_meta, metadata_dir
 
 if TYPE_CHECKING:
+    from pytest_mock import MockerFixture
+
     from conda_build.metadata import MetaData
 
 
@@ -345,3 +348,24 @@ def test_copy_readme(testing_metadata: MetaData, readme: str):
     Path(testing_metadata.config.work_dir, readme).touch()
     build.copy_readme(testing_metadata)
     assert Path(testing_metadata.config.info_dir, readme).exists()
+
+
+@pytest.mark.skipif(not on_win, reason="WSL is only on Windows")
+def test_wsl_unsupported(
+    testing_metadata: MetaData,
+    mocker: MockerFixture,
+    tmp_path: Path,
+):
+    mocker.patch(
+        "conda_build.os_utils.external.find_executable",
+        return_value="C:\\Windows\\System32\\bash.exe",
+    )
+
+    (script := tmp_path / "install.sh").touch()
+    with pytest.raises(CondaBuildUserError):
+        build.bundle_conda(
+            output={"script": script},
+            metadata=testing_metadata,
+            env={},
+            stats={},
+        )