closes bpo-31650: PEP 552 (Deterministic pycs) implementation (#4575)
Python now supports checking bytecode cache up-to-dateness with a hash of the
source contents rather than volatile source metadata. See the PEP for details.
While a fairly straightforward idea, quite a lot of code had to be modified due
to the pervasiveness of pyc implementation details in the codebase. Changes in
this commit include:
- The core changes to importlib to understand how to read, validate, and
regenerate hash-based pycs.
- Support for generating hash-based pycs in py_compile and compileall.
- Modifications to our siphash implementation to support passing a custom
key. We then expose it to importlib through _imp.
- Updates to all places in the interpreter, standard library, and tests that
manually generate or parse pyc files to grok the new format.
- Support in the interpreter command line code for long options like
--check-hash-based-pycs.
- Tests and documentation for all of the above.
diff --git a/Include/internal/import.h b/Include/internal/import.h
new file mode 100644
index 0000000..4746e75
--- /dev/null
+++ b/Include/internal/import.h
@@ -0,0 +1,6 @@
+#ifndef Py_INTERNAL_IMPORT_H
+#define Py_INTERNAL_IMPORT_H
+
+extern const char *_Py_CheckHashBasedPycsMode;
+
+#endif