Extract local functions and type them

They could get tested independently.
This was mostly done to understand their purpose.

Author: michaelosthege

pytensor/link/c/cmodule.py

@@ -20,7 +20,7 @@
 import textwrap
 import time
 import warnings
-from collections.abc import Callable
+from collections.abc import Callable, Collection, Sequence
 from contextlib import AbstractContextManager, nullcontext
 from io import BytesIO, StringIO
 from pathlib import Path
@@ -2736,6 +2736,96 @@ def check_mkl_openmp():
         )
 
 
+def _check_required_file(
+    paths: Collection[Path],
+    required_regexs: Collection[str | re.Pattern[str]],
+) -> list[tuple[str, str]]:
+    """Select path parents for each required pattern."""
+    libs: list[tuple[str, str]] = []
+    for req in required_regexs:
+        found = False
+        for path in paths:
+            m = re.search(req, path.name)
+            if m:
+                libs.append((str(path.parent), m.string[slice(*m.span())]))
+                found = True
+                break
+        if not found:
+            _logger.debug("Required file '%s' not found", req)
+            raise RuntimeError(f"Required file {req} not found")
+    return libs
+
+
+def _get_cxx_library_dirs() -> list[str]:
+    """Query C++ search dirs and return those the existing ones."""
+    cmd = [config.cxx, "-print-search-dirs"]
+    p = subprocess_Popen(
+        cmd,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        stdin=subprocess.PIPE,
+    )
+    (stdout, stderr) = p.communicate(input=b"")
+    if p.returncode != 0:
+        warnings.warn(
+            "Pytensor cxx failed to communicate its search dirs. As a consequence, "
+            "it might not be possible to automatically determine the blas link flags to use.\n"
+            f"Command that was run: {config.cxx} -print-search-dirs\n"
+            f"Output printed to stderr: {stderr.decode(sys.stderr.encoding)}"
+        )
+        return []
+
+    maybe_lib_dirs = [
+        [Path(p).resolve() for p in line[len("libraries: =") :].split(":")]
+        for line in stdout.decode(sys.getdefaultencoding()).splitlines()
+        if line.startswith("libraries: =")
+    ]
+    if not maybe_lib_dirs:
+        return []
+    return [str(d) for d in maybe_lib_dirs[0] if d.exists() and d.is_dir()]
+
+
+def _check_libs(
+    all_libs: Collection[Path],
+    required_libs: Collection[str | re.Pattern],
+    extra_compile_flags: Sequence[str] = (),
+    cxx_library_dirs: Sequence[str] = (),
+) -> str:
+    """Assembly library paths and try BLAS flags, returning the flags on success."""
+    found_libs = _check_required_file(
+        all_libs,
+        required_libs,
+    )
+    path_quote = '"' if sys.platform == "win32" else ""
+    libdir_ldflags = list(
+        dict.fromkeys(
+            [
+                f"-L{path_quote}{lib_path}{path_quote}"
+                for lib_path, _ in found_libs
+                if lib_path not in cxx_library_dirs
+            ]
+        )
+    )
+
+    flags = (
+        libdir_ldflags
+        + [f"-l{lib_name}" for _, lib_name in found_libs]
+        + list(extra_compile_flags)
+    )
+    res = try_blas_flag(flags)
+    if not res:
+        _logger.debug("Supplied flags '%s' failed to compile", res)
+        raise RuntimeError(f"Supplied flags {flags} failed to compile")
+
+    if any("mkl" in flag for flag in flags):
+        try:
+            check_mkl_openmp()
+        except Exception as e:
+            _logger.debug(e)
+    _logger.debug("The following blas flags will be used: '%s'", res)
+    return res
+
+
 def default_blas_ldflags() -> str:
     """Look for an available BLAS implementation in the system.
 
@@ -2763,88 +2853,6 @@ def default_blas_ldflags() -> str:
 
     """
 
-    def check_required_file(paths, required_regexs):
-        libs = []
-        for req in required_regexs:
-            found = False
-            for path in paths:
-                m = re.search(req, path.name)
-                if m:
-                    libs.append((str(path.parent), m.string[slice(*m.span())]))
-                    found = True
-                    break
-            if not found:
-                _logger.debug("Required file '%s' not found", req)
-                raise RuntimeError(f"Required file {req} not found")
-        return libs
-
-    def get_cxx_library_dirs():
-        cmd = [config.cxx, "-print-search-dirs"]
-        p = subprocess_Popen(
-            cmd,
-            stdout=subprocess.PIPE,
-            stderr=subprocess.PIPE,
-            stdin=subprocess.PIPE,
-        )
-        (stdout, stderr) = p.communicate(input=b"")
-        if p.returncode != 0:
-            warnings.warn(
-                "Pytensor cxx failed to communicate its search dirs. As a consequence, "
-                "it might not be possible to automatically determine the blas link flags to use.\n"
-                f"Command that was run: {config.cxx} -print-search-dirs\n"
-                f"Output printed to stderr: {stderr.decode(sys.stderr.encoding)}"
-            )
-            return []
-
-        maybe_lib_dirs = [
-            [Path(p).resolve() for p in line[len("libraries: =") :].split(":")]
-            for line in stdout.decode(sys.getdefaultencoding()).splitlines()
-            if line.startswith("libraries: =")
-        ]
-        if len(maybe_lib_dirs) > 0:
-            maybe_lib_dirs = maybe_lib_dirs[0]
-        return [str(d) for d in maybe_lib_dirs if d.exists() and d.is_dir()]
-
-    def check_libs(
-        all_libs, required_libs, extra_compile_flags=None, cxx_library_dirs=None
-    ) -> str:
-        if cxx_library_dirs is None:
-            cxx_library_dirs = []
-        if extra_compile_flags is None:
-            extra_compile_flags = []
-        found_libs = check_required_file(
-            all_libs,
-            required_libs,
-        )
-        path_quote = '"' if sys.platform == "win32" else ""
-        libdir_ldflags = list(
-            dict.fromkeys(
-                [
-                    f"-L{path_quote}{lib_path}{path_quote}"
-                    for lib_path, _ in found_libs
-                    if lib_path not in cxx_library_dirs
-                ]
-            )
-        )
-
-        flags = (
-            libdir_ldflags
-            + [f"-l{lib_name}" for _, lib_name in found_libs]
-            + extra_compile_flags
-        )
-        res = try_blas_flag(flags)
-        if res:
-            if any("mkl" in flag for flag in flags):
-                try:
-                    check_mkl_openmp()
-                except Exception as e:
-                    _logger.debug(e)
-            _logger.debug("The following blas flags will be used: '%s'", res)
-            return res
-        else:
-            _logger.debug("Supplied flags '%s' failed to compile", res)
-            raise RuntimeError(f"Supplied flags {flags} failed to compile")
-
     # If no compiler is available we default to empty ldflags
     if not config.cxx:
         return ""
@@ -2854,7 +2862,7 @@ def check_libs(
     else:
         rpath = None
 
-    cxx_library_dirs = get_cxx_library_dirs()
+    cxx_library_dirs = _get_cxx_library_dirs()
     searched_library_dirs = cxx_library_dirs + _std_lib_dirs
     if sys.platform == "win32":
         # Conda on Windows saves MKL libraries under CONDA_PREFIX\Library\bin
@@ -2884,7 +2892,7 @@ def check_libs(
     try:
         # 1. Try to use MKL with INTEL OpenMP threading
         _logger.debug("Checking MKL flags with intel threading")
-        return check_libs(
+        return _check_libs(
             all_libs,
             required_libs=[
                 "mkl_core",
@@ -2901,7 +2909,7 @@ def check_libs(
     try:
         # 2. Try to use MKL with GNU OpenMP threading
         _logger.debug("Checking MKL flags with GNU OpenMP threading")
-        return check_libs(
+        return _check_libs(
             all_libs,
             required_libs=["mkl_core", "mkl_rt", "mkl_gnu_thread", "gomp", "pthread"],
             extra_compile_flags=[f"-Wl,-rpath,{rpath}"] if rpath is not None else [],
@@ -2924,7 +2932,7 @@ def check_libs(
     try:
         _logger.debug("Checking Lapack + blas")
         # 4. Try to use LAPACK + BLAS
-        return check_libs(
+        return _check_libs(
             all_libs,
             required_libs=["lapack", "blas", "cblas", "m"],
             extra_compile_flags=[f"-Wl,-rpath,{rpath}"] if rpath is not None else [],
@@ -2935,7 +2943,7 @@ def check_libs(
     try:
         # 5. Try to use BLAS alone
         _logger.debug("Checking blas alone")
-        return check_libs(
+        return _check_libs(
             all_libs,
             required_libs=["blas", "cblas"],
             extra_compile_flags=[f"-Wl,-rpath,{rpath}"] if rpath is not None else [],
@@ -2946,7 +2954,7 @@ def check_libs(
     try:
         # 6. Try to use openblas
         _logger.debug("Checking openblas")
-        return check_libs(
+        return _check_libs(
             all_libs,
             required_libs=["openblas", "gfortran", "gomp", "m"],
             extra_compile_flags=["-fopenmp", f"-Wl,-rpath,{rpath}"]