Don't raise an error if there are spaces in file paths supplied to PIP_CONSTRAINT

CHANGELOG.md

@@ -7,10 +7,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
 - Fixed a regression in quoting of pip arguments introduced in
   [#185](https://github.com/pyodide/pyodide-build/pull/185).
   [#209](https://github.com/pyodide/pyodide-build/pull/209)
 
+- `pyodide-build` now correctly works with file paths with spaces passed to the `PIP_CONSTRAINT` environment variable.
+  [#210](https://github.com/pyodide/pyodide-build/pull/210)
+
 ## [0.30.4] - 2025/05/20
 
 - Fixed compatibility with `virtualenv` 20.31 and later. The Pyodide virtual environment via `pyodide venv` no longer seeds

pyodide_build/build_env.py

@@ -14,7 +14,12 @@
 from packaging.tags import Tag, compatible_tags, cpython_tags
 
 from pyodide_build import __version__
-from pyodide_build.common import default_xbuildenv_path, search_pyproject_toml, to_bool
+from pyodide_build.common import (
+    default_xbuildenv_path,
+    path_to_uri_if_spaces,
+    search_pyproject_toml,
+    to_bool,
+)
 
 RUST_BUILD_PRELUDE = """
 rustup default ${RUST_TOOLCHAIN}
@@ -334,13 +339,9 @@ def _create_constraints_file() -> str:
     if not constraints:
         return ""
 
-    if len(constraints.split(maxsplit=1)) > 1:
-        raise ValueError(
-            "PIP_CONSTRAINT contains spaces so pip will misinterpret it. Make sure the path to pyodide has no spaces.\n"
-            "See https://github.com/pypa/pip/issues/13283"
-        )
-
     constraints_file = Path(constraints)
+    constraints = path_to_uri_if_spaces(constraints_file)
+
     if not constraints_file.is_file():
         constraints_file.parent.mkdir(parents=True, exist_ok=True)
         constraints_file.write_text("")

pyodide_build/common.py

@@ -646,3 +646,24 @@ def retrying_rmtree(d):
             else:
                 raise
     raise RuntimeError(f"shutil.rmtree('{d}') failed with ENOTEMPTY three times")
+
+
+def path_to_uri_if_spaces(path: str | Path) -> str:
+    """
+    Convert a file path to a URI if it contains spaces, otherwise return as string.
+
+    This works around a pip bug where paths with spaces in PIP_CONSTRAINT are
+    misinterpreted as multiple files; see https://github.com/pypa/pip/issues/13283
+
+    Parameters
+    ----------
+    path
+        The file path to potentially convert
+
+    Returns
+    -------
+    str
+        The path as a URI if it contains spaces, or otherwise as a string.
+    """
+    path_obj = Path(path)
+    return path_obj.as_uri() if " " in str(path_obj) else str(path_obj)

pyodide_build/recipe/builder.py

@@ -40,6 +40,7 @@
     find_matching_wheel,
     make_zip_archive,
     modify_wheel,
+    path_to_uri_if_spaces,
     retag_wheel,
     retrying_rmtree,
 )
@@ -136,11 +137,9 @@ def __init__(
         self.build_dir = (
             Path(build_dir).resolve() if build_dir else self.pkg_root / "build"
         )
-        if len(str(self.build_dir).split(maxsplit=1)) > 1:
-            raise ValueError(
-                "PIP_CONSTRAINT contains spaces so pip will misinterpret it. Make sure the path to the package build directory has no spaces.\n"
-                "See https://github.com/pypa/pip/issues/13283"
-            )
+        # If a path to a file specified PIP_CONSTRAINT contains spaces, pip will misinterpret
+        # it as multiple files; see https://github.com/pypa/pip/issues/13283
+        # We work around this by converting the path to a URI when needed.
         self.library_install_prefix = self.build_dir.parent.parent / ".libs"
         self.src_extract_dir = (
             self.build_dir / self.fullname
@@ -367,7 +366,7 @@ def _download_and_extract(self) -> None:
         shutil.move(self.build_dir / extract_dir_name, self.src_extract_dir)
         self.src_dist_dir.mkdir(parents=True, exist_ok=True)
 
-    def _create_constraints_file(self) -> str:
+    def _create_constraints_file(self, filename: str = "constraints.txt") -> str:
         """
         Creates a pip constraints file by concatenating global constraints (PIP_CONSTRAINT)
         with constraints specific to this package.
@@ -381,12 +380,17 @@ def _create_constraints_file(self) -> str:
             # nothing to override
             return host_constraints
 
-        new_constraints_file = self.build_dir / "constraints.txt"
+        new_constraints_file = self.build_dir / filename
         with new_constraints_file.open("w") as f:
             for constraint in constraints:
                 f.write(constraint + "\n")
 
-        return host_constraints + " " + str(new_constraints_file)
+        new_constraints_str = path_to_uri_if_spaces(new_constraints_file)
+
+        if host_constraints:
+            return host_constraints + " " + new_constraints_str
+        else:
+            return new_constraints_str
 
     def _compile(
         self,

pyodide_build/tests/recipe/test_builder.py

@@ -203,6 +203,29 @@ def test_create_constraints_file_override(tmp_path, dummy_xbuildenv):
     assert data[-3:] == ["numpy < 2.0", "pytest == 7.0", "setuptools < 75"], data
 
 
+def test_create_constraints_file_space_in_path_uri_conversion(
+    tmp_path, dummy_xbuildenv
+):
+    build_dir_with_spaces = tmp_path / "build dir with spaces"
+    build_dir_with_spaces.mkdir()
+
+    builder = RecipeBuilder.get_builder(
+        recipe=RECIPE_DIR / "pkg_test_constraint",
+        build_args=BuildArgs(),
+        build_dir=build_dir_with_spaces,
+    )
+
+    paths = builder._create_constraints_file(filename="constraints with space.txt")
+
+    parts = paths.split()
+    if len(parts) > 1:
+        last_part = parts[-1]
+        if "with%20space" in last_part or last_part.startswith("file://"):
+            assert True
+        else:
+            assert "constraints with space.txt" in last_part
+
+
 class MockSourceSpec(_SourceSpec):
     @pydantic.model_validator(mode="after")
     def _check_patches_extra(self) -> Self:

pyodide_build/tests/test_build_env.py

@@ -237,3 +237,23 @@ def test_wheel_paths(dummy_xbuildenv):
             f"{current_version}-none-any",
         ]
     )
+
+
+def test_create_constraints_file_with_spaces(tmp_path, monkeypatch, reset_cache):
+    from pyodide_build.build_env import _create_constraints_file
+
+    constraints_dir = tmp_path / "path with spaces"
+    constraints_dir.mkdir()
+    constraints_file = constraints_dir / "constraints.txt"
+    constraints_file.write_text("numpy==1.0\n")
+
+    def mock_get_build_flag(name):
+        if name == "PIP_CONSTRAINT":
+            return str(constraints_file)
+
+    monkeypatch.setattr("pyodide_build.build_env.get_build_flag", mock_get_build_flag)
+
+    result = _create_constraints_file()
+
+    assert result.startswith("file://")
+    assert "path%20with%20spaces" in result or "path with spaces" in result