bpo-40268: Rename _PyInterpreterState_GET_UNSAFE() (GH-19509)

Rename _PyInterpreterState_GET_UNSAFE() to _PyInterpreterState_GET()
for consistency with _PyThreadState_GET() and to have a shorter name
(help to fit into 80 columns).

Add also "assert(tstate != NULL);" to the function.
diff --git a/Python/_warnings.c b/Python/_warnings.c
index d005f12..0236cab 100644
--- a/Python/_warnings.c
+++ b/Python/_warnings.c
@@ -212,7 +212,7 @@
            gone, then we can't even use PyImport_GetModule without triggering
            an interpreter abort.
         */
-        if (!_PyInterpreterState_GET_UNSAFE()->modules) {
+        if (!_PyInterpreterState_GET()->modules) {
             return NULL;
         }
         warnings_module = PyImport_GetModule(warnings_str);
@@ -840,7 +840,7 @@
     }
 
     if (f == NULL) {
-        globals = _PyInterpreterState_GET_UNSAFE()->sysdict;
+        globals = _PyInterpreterState_GET()->sysdict;
         *filename = PyUnicode_FromString("sys");
         *lineno = 1;
     }
diff --git a/Python/ceval.c b/Python/ceval.c
index b712920..fc720b4 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -5562,7 +5562,7 @@
 Py_ssize_t
 _PyEval_RequestCodeExtraIndex(freefunc free)
 {
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     Py_ssize_t new_index;
 
     if (interp->co_extra_user_count == MAX_CO_EXTRA_USERS - 1) {
diff --git a/Python/codecs.c b/Python/codecs.c
index 6691985..32cc110 100644
--- a/Python/codecs.c
+++ b/Python/codecs.c
@@ -33,7 +33,7 @@
 
 int PyCodec_Register(PyObject *search_function)
 {
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     if (interp->codec_search_path == NULL && _PyCodecRegistry_Init())
         goto onError;
     if (search_function == NULL) {
@@ -105,7 +105,7 @@
         return NULL;
     }
 
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     if (interp->codec_search_path == NULL && _PyCodecRegistry_Init()) {
         return NULL;
     }
@@ -188,7 +188,7 @@
     PyObject *v;
     int result;
 
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     if (interp->codec_search_path == NULL) {
         return -1;
     }
@@ -621,7 +621,7 @@
    Return 0 on success, -1 on error */
 int PyCodec_RegisterError(const char *name, PyObject *error)
 {
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     if (interp->codec_search_path == NULL && _PyCodecRegistry_Init())
         return -1;
     if (!PyCallable_Check(error)) {
@@ -639,7 +639,7 @@
 {
     PyObject *handler = NULL;
 
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     if (interp->codec_search_path == NULL && _PyCodecRegistry_Init())
         return NULL;
 
@@ -1491,7 +1491,7 @@
         }
     };
 
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     PyObject *mod;
 
     if (interp->codec_search_path != NULL)
diff --git a/Python/dynload_shlib.c b/Python/dynload_shlib.c
index 223e0d0..082154d 100644
--- a/Python/dynload_shlib.c
+++ b/Python/dynload_shlib.c
@@ -3,7 +3,7 @@
 
 #include "Python.h"
 #include "pycore_interp.h"    // _PyInterpreterState.dlopenflags
-#include "pycore_pystate.h"   // _PyInterpreterState_GET_UNSAFE()
+#include "pycore_pystate.h"   // _PyInterpreterState_GET()
 #include "importdl.h"
 
 #include <sys/types.h>
@@ -95,7 +95,7 @@
         }
     }
 
-    dlopenflags = _PyInterpreterState_GET_UNSAFE()->dlopenflags;
+    dlopenflags = _PyInterpreterState_GET()->dlopenflags;
 
     handle = dlopen(pathname, dlopenflags);
 
diff --git a/Python/import.c b/Python/import.c
index 3bf8fe0..042691d 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -310,7 +310,7 @@
 PyObject *
 PyImport_GetModuleDict(void)
 {
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     if (interp->modules == NULL) {
         Py_FatalError("interpreter has no modules dictionary");
     }
@@ -644,7 +644,7 @@
 PyImport_GetMagicNumber(void)
 {
     long res;
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     PyObject *external, *pyc_magic;
 
     external = PyObject_GetAttrString(interp->importlib, "_bootstrap_external");
@@ -980,7 +980,7 @@
             goto error;
     }
     else if (cpathobj != NULL) {
-        PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+        PyInterpreterState *interp = _PyInterpreterState_GET();
         _Py_IDENTIFIER(_get_sourcefile);
 
         if (interp == NULL) {
diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index c2a0781..ac0ea10 100644
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -2355,7 +2355,7 @@
 /* For the atexit module. */
 void _Py_PyAtExit(void (*func)(PyObject *), PyObject *module)
 {
-    PyInterpreterState *is = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *is = _PyInterpreterState_GET();
 
     /* Guard against API misuse (see bpo-17852) */
     assert(is->pyexitfunc == NULL || is->pyexitfunc == func);
diff --git a/Python/pystate.c b/Python/pystate.c
index 3636dc9..65d46a2 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -661,7 +661,7 @@
 PyState_FindModule(struct PyModuleDef* module)
 {
     Py_ssize_t index = module->m_base.m_index;
-    PyInterpreterState *state = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *state = _PyInterpreterState_GET();
     PyObject *res;
     if (module->m_slots) {
         return NULL;
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 522d152..d1165e2 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -347,7 +347,7 @@
     filename_obj = PyUnicode_DecodeFSDefault(filename);
     if (filename_obj == NULL)
         return -1;
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     bootstrap = PyObject_GetAttrString(interp->importlib,
                                        "_bootstrap_external");
     if (bootstrap != NULL) {
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 814e4ab..6b3a1c3 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -847,7 +847,7 @@
 sys_getfilesystemencoding_impl(PyObject *module)
 /*[clinic end generated code: output=1dc4bdbe9be44aa7 input=8475f8649b8c7d8c]*/
 {
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     const PyConfig *config = _PyInterpreterState_GetConfig(interp);
     return PyUnicode_FromWideChar(config->filesystem_encoding, -1);
 }
@@ -862,7 +862,7 @@
 sys_getfilesystemencodeerrors_impl(PyObject *module)
 /*[clinic end generated code: output=ba77b36bbf7c96f5 input=22a1e8365566f1e5]*/
 {
-    PyInterpreterState *interp = _PyInterpreterState_GET_UNSAFE();
+    PyInterpreterState *interp = _PyInterpreterState_GET();
     const PyConfig *config = _PyInterpreterState_GetConfig(interp);
     return PyUnicode_FromWideChar(config->filesystem_errors, -1);
 }
diff --git a/Python/thread.c b/Python/thread.c
index ec6909c..bac0e69 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -92,7 +92,7 @@
 size_t
 PyThread_get_stacksize(void)
 {
-    return _PyInterpreterState_GET_UNSAFE()->pythread_stacksize;
+    return _PyInterpreterState_GET()->pythread_stacksize;
 }
 
 /* Only platforms defining a THREAD_SET_STACKSIZE() macro
diff --git a/Python/thread_nt.h b/Python/thread_nt.h
index e4bd0f7..05b982d 100644
--- a/Python/thread_nt.h
+++ b/Python/thread_nt.h
@@ -359,13 +359,13 @@
 {
     /* set to default */
     if (size == 0) {
-        _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = 0;
+        _PyInterpreterState_GET()->pythread_stacksize = 0;
         return 0;
     }
 
     /* valid range? */
     if (size >= THREAD_MIN_STACKSIZE && size < THREAD_MAX_STACKSIZE) {
-        _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = size;
+        _PyInterpreterState_GET()->pythread_stacksize = size;
         return 0;
     }
 
diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index 440d845..cf4e854 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -735,7 +735,7 @@
 
     /* set to default */
     if (size == 0) {
-        _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = 0;
+        _PyInterpreterState_GET()->pythread_stacksize = 0;
         return 0;
     }
 
@@ -752,7 +752,7 @@
             rc = pthread_attr_setstacksize(&attrs, size);
             pthread_attr_destroy(&attrs);
             if (rc == 0) {
-                _PyInterpreterState_GET_UNSAFE()->pythread_stacksize = size;
+                _PyInterpreterState_GET()->pythread_stacksize = size;
                 return 0;
             }
         }