bpo-36142: Add _PyPreConfig_SetAllocator() (GH-12187)

* _PyPreConfig_Write() now reallocates the pre-configuration with the
  new memory allocator.
* It is no longer needed to force the "default raw memory allocator"
  to clear pre-configuration and core configuration. Simplify the
  code.
* _PyPreConfig_Write() now does nothing if called after
  Py_Initialize(): no longer check if the allocator is the same.
* Remove _PyMem_GetDebugAllocatorsName(): dev mode sets again
  allocator to "debug".

1 files changed, 2 insertions, 23 deletions

diff --git a/Modules/main.c b/Modules/main.c
index 9a2347e2b2..14055c8101 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -289,17 +289,9 @@ _PyMainInterpreterConfig_Read(_PyMainInterpreterConfig *main_config,
 static _PyInitError
 preconfig_read_write(_PyPreConfig *config, const _PyArgv *args)
 {
-    _PyInitError err;
-
-    PyMemAllocatorEx old_alloc;
-    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
     _PyPreConfig_GetGlobalConfig(config);
 
-    err = _PyPreConfig_ReadFromArgv(config, args);
-
-    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
+    _PyInitError err = _PyPreConfig_ReadFromArgv(config, args);
     if (_Py_INIT_FAILED(err)) {
         return err;
     }
@@ -312,17 +304,9 @@ static _PyInitError
 config_read_write(_PyCoreConfig *config, const _PyArgv *args,
                   const _PyPreConfig *preconfig)
 {
-    _PyInitError err;
-
-    PyMemAllocatorEx old_alloc;
-    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
     _PyCoreConfig_GetGlobalConfig(config);
 
-    err = _PyCoreConfig_ReadFromArgv(config, args, preconfig);
-
-    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
+    _PyInitError err = _PyCoreConfig_ReadFromArgv(config, args, preconfig);
     if (_Py_INIT_FAILED(err)) {
         return err;
     }
@@ -355,7 +339,6 @@ static _PyInitError
 pymain_init(const _PyArgv *args, PyInterpreterState **interp_p)
 {
     _PyInitError err;
-    PyMemAllocatorEx old_alloc;
 
     err = _PyRuntime_Initialize();
     if (_Py_INIT_FAILED(err)) {
@@ -402,12 +385,8 @@ pymain_init(const _PyArgv *args, PyInterpreterState **interp_p)
     err = _Py_INIT_OK();
 
 done:
-    _PyMem_SetDefaultAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
-
     _PyPreConfig_Clear(preconfig);
     _PyCoreConfig_Clear(config);
-
-    PyMem_SetAllocator(PYMEM_DOMAIN_RAW, &old_alloc);
     return err;
 }