bpo-40521: Make empty Unicode string per interpreter (GH-21096)
Each interpreter now has its own empty Unicode string singleton.
diff --git a/Objects/stringlib/asciilib.h b/Objects/stringlib/asciilib.h
index 8599d38..7749e8f 100644
--- a/Objects/stringlib/asciilib.h
+++ b/Objects/stringlib/asciilib.h
@@ -11,7 +11,6 @@
#define STRINGLIB_CHAR Py_UCS1
#define STRINGLIB_TYPE_NAME "unicode"
#define STRINGLIB_PARSE_CODE "U"
-#define STRINGLIB_GET_EMPTY() unicode_empty
#define STRINGLIB_ISSPACE Py_UNICODE_ISSPACE
#define STRINGLIB_ISLINEBREAK BLOOM_LINEBREAK
#define STRINGLIB_ISDECIMAL Py_UNICODE_ISDECIMAL
diff --git a/Objects/stringlib/partition.h b/Objects/stringlib/partition.h
index 3731df5..bcc2176 100644
--- a/Objects/stringlib/partition.h
+++ b/Objects/stringlib/partition.h
@@ -1,9 +1,14 @@
/* stringlib: partition implementation */
#ifndef STRINGLIB_FASTSEARCH_H
-#error must include "stringlib/fastsearch.h" before including this module
+# error must include "stringlib/fastsearch.h" before including this module
#endif
+#if !STRINGLIB_MUTABLE && !defined(STRINGLIB_GET_EMPTY)
+# error "STRINGLIB_GET_EMPTY must be defined if STRINGLIB_MUTABLE is zero"
+#endif
+
+
Py_LOCAL_INLINE(PyObject*)
STRINGLIB(partition)(PyObject* str_obj,
const STRINGLIB_CHAR* str, Py_ssize_t str_len,
diff --git a/Objects/stringlib/stringdefs.h b/Objects/stringlib/stringdefs.h
index c12ecc5..88641b2 100644
--- a/Objects/stringlib/stringdefs.h
+++ b/Objects/stringlib/stringdefs.h
@@ -1,10 +1,6 @@
#ifndef STRINGLIB_STRINGDEFS_H
#define STRINGLIB_STRINGDEFS_H
-#ifndef STRINGLIB_GET_EMPTY
-# error "STRINGLIB_GET_EMPTY macro must be defined"
-#endif
-
/* this is sort of a hack. there's at least one place (formatting
floats) where some stringlib code takes a different path if it's
compiled as unicode. */
diff --git a/Objects/stringlib/ucs1lib.h b/Objects/stringlib/ucs1lib.h
index bdf3035..5b0b8a0 100644
--- a/Objects/stringlib/ucs1lib.h
+++ b/Objects/stringlib/ucs1lib.h
@@ -11,7 +11,6 @@
#define STRINGLIB_CHAR Py_UCS1
#define STRINGLIB_TYPE_NAME "unicode"
#define STRINGLIB_PARSE_CODE "U"
-#define STRINGLIB_GET_EMPTY() unicode_empty
#define STRINGLIB_ISSPACE Py_UNICODE_ISSPACE
#define STRINGLIB_ISLINEBREAK BLOOM_LINEBREAK
#define STRINGLIB_ISDECIMAL Py_UNICODE_ISDECIMAL
diff --git a/Objects/stringlib/ucs2lib.h b/Objects/stringlib/ucs2lib.h
index 9d68888..6af0151 100644
--- a/Objects/stringlib/ucs2lib.h
+++ b/Objects/stringlib/ucs2lib.h
@@ -11,7 +11,6 @@
#define STRINGLIB_CHAR Py_UCS2
#define STRINGLIB_TYPE_NAME "unicode"
#define STRINGLIB_PARSE_CODE "U"
-#define STRINGLIB_GET_EMPTY() unicode_empty
#define STRINGLIB_ISSPACE Py_UNICODE_ISSPACE
#define STRINGLIB_ISLINEBREAK BLOOM_LINEBREAK
#define STRINGLIB_ISDECIMAL Py_UNICODE_ISDECIMAL
diff --git a/Objects/stringlib/ucs4lib.h b/Objects/stringlib/ucs4lib.h
index c7dfa52..39071a0 100644
--- a/Objects/stringlib/ucs4lib.h
+++ b/Objects/stringlib/ucs4lib.h
@@ -11,7 +11,6 @@
#define STRINGLIB_CHAR Py_UCS4
#define STRINGLIB_TYPE_NAME "unicode"
#define STRINGLIB_PARSE_CODE "U"
-#define STRINGLIB_GET_EMPTY() unicode_empty
#define STRINGLIB_ISSPACE Py_UNICODE_ISSPACE
#define STRINGLIB_ISLINEBREAK BLOOM_LINEBREAK
#define STRINGLIB_ISDECIMAL Py_UNICODE_ISDECIMAL
diff --git a/Objects/stringlib/unicodedefs.h b/Objects/stringlib/unicodedefs.h
index e4d4163..5ea79cd 100644
--- a/Objects/stringlib/unicodedefs.h
+++ b/Objects/stringlib/unicodedefs.h
@@ -13,7 +13,6 @@
#define STRINGLIB_CHAR Py_UNICODE
#define STRINGLIB_TYPE_NAME "unicode"
#define STRINGLIB_PARSE_CODE "U"
-#define STRINGLIB_GET_EMPTY() unicode_empty
#define STRINGLIB_ISSPACE Py_UNICODE_ISSPACE
#define STRINGLIB_ISLINEBREAK BLOOM_LINEBREAK
#define STRINGLIB_ISDECIMAL Py_UNICODE_ISDECIMAL