Allow overriding _f2c_fixes.py from user (#8)

While most parts of pyodide-build are decoupled with pyodide/pyodide,
`_f2c_fixes.py` file that is used to build scipy is highly coupled with
the scipy recipe in pyodide/pyodide.

It would be very inefficient if we need to update pyodide-build whenever
we fix scipy (e.g. pyodide/pyodide#4818).
Therefore, this add a private config variable `_f2c_fixes_wrapper`,
which allows users to modify override `_f2c_fixes.py` file without
touching pyodide-build itself.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: ryanking13

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## [0.27.3] - 2024/07/17
+
+- It is now possible to override `_f2c_fixes.py` file, with `_f2c_fixes_wrapper` variable.
+  [#8](https://github.com/pyodide/pyodide-build/pull/8)
+
 ## [0.27.2] - 2024/07/11
 
 ## Changed

pyodide_build/config.py

@@ -169,6 +169,8 @@ def to_env(self) -> dict[str, str]:
     "home": "HOME",
     "path": "PATH",
     "zip_compression_level": "PYODIDE_ZIP_COMPRESSION_LEVEL",
+    # maintainer only
+    "_f2c_fixes_wrapper": "_F2C_FIXES_WRAPPER",
 }
 
 BUILD_VAR_TO_KEY = {v: k for k, v in BUILD_KEY_TO_VAR.items()}
@@ -181,6 +183,8 @@ def to_env(self) -> dict[str, str]:
     "ldflags",
     "rust_toolchain",
     "meson_cross_file",
+    # maintainer only
+    "_f2c_fixes_wrapper",
 }
 
 # Default configuration values.
@@ -197,6 +201,8 @@ def to_env(self) -> dict[str, str]:
     "rust_toolchain": "nightly-2024-01-29",
     # Other configuration
     "pyodide_jobs": "1",
+    # maintainer only
+    "_f2c_fixes_wrapper": "",
 }
 
 # Default configs that are computed from other values (often from Makefile.envs)

pyodide_build/pypabuild.py

@@ -15,7 +15,7 @@
 from build.env import DefaultIsolatedEnv
 from packaging.requirements import Requirement
 
-from . import common, pywasmcross
+from . import _f2c_fixes, common, pywasmcross
 from .build_env import (
     get_build_flag,
     get_hostsitepackages,
@@ -214,10 +214,20 @@ def make_command_wrapper_symlinks(symlink_dir: Path) -> dict[str, str]:
     The dictionary of compiler environment variables that points to the symlinks.
     """
 
+    # For maintainers:
+    # - you can set "_f2c_fixes_wrapper" variable in pyproject.toml
+    # in order to change the script to use when cross-compiling
+    # this is only for maintainers and *should* not be used by others
+
     pywasmcross_exe = symlink_dir / "pywasmcross.py"
-    shutil.copy2(pywasmcross.__file__, pywasmcross_exe)
+    pywasmcross_origin = pywasmcross.__file__
+    shutil.copy2(pywasmcross_origin, pywasmcross_exe)
     pywasmcross_exe.chmod(0o755)
 
+    f2c_fixes_exe = symlink_dir / "_f2c_fixes.py"
+    f2c_fixes_origin = get_build_flag("_F2C_FIXES_WRAPPER") or _f2c_fixes.__file__
+    shutil.copy2(f2c_fixes_origin, f2c_fixes_exe)
+
     env = {}
     for symlink in pywasmcross.SYMLINKS:
         symlink_path = symlink_dir / symlink
@@ -266,7 +276,7 @@ def get_build_env(
         env.update(make_command_wrapper_symlinks(symlink_dir))
 
         sysconfig_dir = Path(get_build_flag("TARGETINSTALLDIR")) / "sysconfigdata"
-        args["PYTHONPATH"] = sys.path + [str(sysconfig_dir)]
+        args["PYTHONPATH"] = sys.path + [str(symlink_dir), str(sysconfig_dir)]
         args["orig__name__"] = __name__
         args["pythoninclude"] = get_build_flag("PYTHONINCLUDE")
         args["PATH"] = env["PATH"]

pyodide_build/pywasmcross.py

@@ -591,7 +591,7 @@ def handle_command(
     """
 
     if line[0] == "gfortran":
-        from pyodide_build._f2c_fixes import replay_f2c
+        from _f2c_fixes import replay_f2c
 
         tmp = replay_f2c(line)
         if tmp is None:
@@ -604,7 +604,7 @@ def handle_command(
     new_args = handle_command_generate_args(line, build_args)
 
     if build_args.pkgname == "scipy":
-        from pyodide_build._f2c_fixes import scipy_fixes
+        from _f2c_fixes import scipy_fixes
 
         scipy_fixes(new_args)
 

pyodide_build/tests/test_pypabuild.py

@@ -50,7 +50,25 @@ def test_make_command_wrapper_symlinks(tmp_path):
         assert key in pypabuild.SYMLINK_ENV_VARS.values()
 
 
-def test_get_build_env(tmp_path):
+def test_make_command_wrapper_symlinks_f2c_wrapper(
+    tmp_path, dummy_xbuildenv, reset_env_vars, reset_cache
+):
+    import os
+
+    dummy_f2c_wrapper = tmp_path / "_dummy_f2c_fixes.py"
+    dummy_f2c_wrapper.write_text("print('Hello, world!')")
+
+    os.environ["_F2C_FIXES_WRAPPER"] = str(dummy_f2c_wrapper)
+
+    symlink_dir = tmp_path
+    pypabuild.make_command_wrapper_symlinks(symlink_dir)
+
+    wrapper = symlink_dir / "_f2c_fixes.py"
+    assert wrapper.exists()
+    assert wrapper.read_text() == dummy_f2c_wrapper.read_text()
+
+
+def test_get_build_env(tmp_path, dummy_xbuildenv):
     build_env_ctx = pypabuild.get_build_env(
         env={"PATH": ""},
         pkgname="",