bpo-29240, bpo-32030: Py_Main() re-reads config if encoding changes (#4899)

bpo-29240, bpo-32030: If the encoding change (C locale coerced or
UTF-8 Mode changed), Py_Main() now reads again the configuration with
the new encoding.

Changes:

* Add _Py_UnixMain() called by main().
* Rename pymain_free_pymain() to pymain_clear_pymain(), it can now be
  called multipled times.
* Rename pymain_parse_cmdline_envvars() to pymain_read_conf().
* Py_Main() now clears orig_argc and orig_argv at exit.
* Remove argv_copy2, Py_Main() doesn't modify argv anymore. There is
  no need anymore to get two copies of the wchar_t** argv.
* _PyCoreConfig: add coerce_c_locale and coerce_c_locale_warn.
* Py_UTF8Mode is now initialized to -1.
* Locale coercion (PEP 538) now respects -I and -E options.

1 files changed, 4 insertions, 3 deletions

diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 604493dc5e..e702f7c6e9 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -29,9 +29,10 @@ const char *Py_FileSystemDefaultEncoding = NULL; /* set by initfsencoding() */
 int Py_HasFileSystemDefaultEncoding = 0;
 #endif
 const char *Py_FileSystemDefaultEncodeErrors = "surrogateescape";
-/* UTF-8 mode (PEP 540): if non-zero, use the UTF-8 encoding, and change stdin
-   and stdout error handler to "surrogateescape". */
-int Py_UTF8Mode = 0;
+/* UTF-8 mode (PEP 540): if equals to 1, use the UTF-8 encoding, and change
+   stdin and stdout error handler to "surrogateescape". It is equal to
+   -1 by default: unknown, will be set by Py_Main() */
+int Py_UTF8Mode = -1;
 
 _Py_IDENTIFIER(__builtins__);
 _Py_IDENTIFIER(__dict__);