Merge branch 'dynamic-loading' into dynamic-loading-3.9

Author: freakboy3742

patch/Python/sitecustomize.py

@@ -2,10 +2,13 @@
 # packages cross-platform. If the folder containing this file is on
 # your PYTHONPATH when you invoke pip, pip will behave as if it were
 # running on {{os}}.
+import distutils.ccompiler
+import distutils.unixccompiler
 import os
 import platform
 import sys
 import sysconfig
+import types
 
 # Make platform.system() return "{{os}}"
 def custom_system():
@@ -19,6 +22,71 @@ def custom_get_platform():
 
 sysconfig.get_platform = custom_get_platform
 
+# Make distutils raise errors if you try to use it to build modules.
+DISABLED_COMPILER_ERROR = "Cannot compile native modules"
+
+distutils.ccompiler.get_default_compiler = lambda *args, **kwargs: "disabled"
+distutils.ccompiler.compiler_class["disabled"] = (
+    "disabledcompiler",
+    "DisabledCompiler",
+    "Compiler disabled ({})".format(DISABLED_COMPILER_ERROR),
+)
+
+
+def disabled_compiler(prefix):
+    # No need to give any more advice here: that will come from the higher-level code in pip.
+    from distutils.errors import DistutilsPlatformError
+
+    raise DistutilsPlatformError("{}: {}".format(prefix, DISABLED_COMPILER_ERROR))
+
+
+class DisabledCompiler(distutils.ccompiler.CCompiler):
+    compiler_type = "disabled"
+
+    def preprocess(*args, **kwargs):
+        disabled_compiler("CCompiler.preprocess")
+
+    def compile(*args, **kwargs):
+        disabled_compiler("CCompiler.compile")
+
+    def create_static_lib(*args, **kwargs):
+        disabled_compiler("CCompiler.create_static_lib")
+
+    def link(*args, **kwargs):
+        disabled_compiler("CCompiler.link")
+
+
+# To maximize the chance of the build getting as far as actually calling compile(), make
+# sure the class has all of the expected attributes.
+for name in [
+    "src_extensions",
+    "obj_extension",
+    "static_lib_extension",
+    "shared_lib_extension",
+    "static_lib_format",
+    "shared_lib_format",
+    "exe_extension",
+]:
+    setattr(
+        DisabledCompiler, name, getattr(distutils.unixccompiler.UnixCCompiler, name)
+    )
+
+DisabledCompiler.executables = {
+    name: [DISABLED_COMPILER_ERROR.replace(" ", "_")]
+    for name in distutils.unixccompiler.UnixCCompiler.executables
+}
+
+disabled_mod = types.ModuleType("distutils.disabledcompiler")
+disabled_mod.DisabledCompiler = DisabledCompiler
+sys.modules["distutils.disabledcompiler"] = disabled_mod
+
+
+# Try to disable native builds for packages which don't use the distutils native build
+# system at all (e.g. uwsgi), or only use it to wrap an external build script (e.g. pynacl).
+for tool in ["ar", "as", "cc", "cxx", "ld"]:
+    os.environ[tool.upper()] = DISABLED_COMPILER_ERROR.replace(" ", "_")
+
+
 # Call the next sitecustomize script if there is one
 # (https://nedbatchelder.com/blog/201001/running_code_at_python_startup.html).
 del sys.modules["sitecustomize"]