fix: escape paths with spaces in pybind11-config (#4874)

* fix: Escape paths with spaces in include list from --includes

* fix: --includes should not use shlex on Windows platforms

* Apply suggestions from code review

* fix: use custom impl

Signed-off-by: Henry Schreiner <[email protected]>

* Support trailing backslashes

Co-authored-by: Henry Schreiner <[email protected]>

---------

Signed-off-by: Henry Schreiner <[email protected]>
Co-authored-by: Markus Bauer <[email protected]>
Co-authored-by: Henry Schreiner <[email protected]>

pybind11/__main__.py

@@ -2,12 +2,35 @@
 from __future__ import annotations
 
 import argparse
+import re
 import sys
 import sysconfig
 
 from ._version import __version__
 from .commands import get_cmake_dir, get_include, get_pkgconfig_dir
 
+# This is the conditional used for os.path being posixpath
+if "posix" in sys.builtin_module_names:
+    from shlex import quote
+elif "nt" in sys.builtin_module_names:
+    # See https://github.com/mesonbuild/meson/blob/db22551ed9d2dd7889abea01cc1c7bba02bf1c75/mesonbuild/utils/universal.py#L1092-L1121
+    # and the original documents:
+    # https://docs.microsoft.com/en-us/cpp/c-language/parsing-c-command-line-arguments and
+    # https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/
+    UNSAFE = re.compile("[ \t\n\r]")
+
+    def quote(s: str) -> str:
+        if s and not UNSAFE.search(s):
+            return s
+
+        # Paths cannot contain a '"' on Windows, so we don't need to worry
+        # about nuanced counting here.
+        return f'"{s}\\"' if s.endswith("\\") else f'"{s}"'
+else:
+
+    def quote(s: str) -> str:
+        return s
+
 
 def print_includes() -> None:
     dirs = [
@@ -22,7 +45,7 @@ def print_includes() -> None:
         if d and d not in unique_dirs:
             unique_dirs.append(d)
 
-    print(" ".join("-I" + d for d in unique_dirs))
+    print(" ".join(quote(f"-I{d}") for d in unique_dirs))
 
 
 def main() -> None:
@@ -54,9 +77,9 @@ def main() -> None:
     if args.includes:
         print_includes()
     if args.cmakedir:
-        print(get_cmake_dir())
+        print(quote(get_cmake_dir()))
     if args.pkgconfigdir:
-        print(get_pkgconfig_dir())
+        print(quote(get_pkgconfig_dir()))
 
 
 if __name__ == "__main__":