BKE_reports: make the API thread-safe.

This commit makes using (most of) `BKE_report` API safe in
multi-threaded situation.

This is achieved by adding a `std::mutex` lock to the `ReportList`
struct (in a slightly convoluted way unfortunately, due to this being a
DNA struct). This lock is then used to make most operations on
`Reportlist` data thread-safe.

Note that while working on this, a few other minor issues aroze in
existing usages of Reportlist by the WM code, mainly the fact that
`wm_init_reports` and `wm_free_reports` were both useless:
  - init was called in a context where there is not yet any WM, so it
    was doing nothing.
  - free was called on a WM that would be later freed (as part of Main
    freeing), which would also call cleanup code for its `reports` data.
Both have been removed.

Further more, `wm_add_default` (which is the only place where a WM ID is
created) did not initialize properly it reports data, this has been
fixed.

This change is related to the wmJob thread-safety tasks and PRs (#112537,
!113548).

Pull Request: https://projects.blender.org/blender/blender/pulls/113561

source/blender/python/intern/bpy_capi_utils.cc

@@ -33,7 +33,7 @@ short BPy_reports_to_error(ReportList *reports, PyObject *exception, const bool
   report_str = BKE_reports_string(reports, RPT_ERROR);
 
   if (clear == true) {
-    BKE_reports_clear(reports);
+    BKE_reports_free(reports);
   }
 
   if (report_str) {

source/blender/python/intern/bpy_capi_utils.h

@@ -18,7 +18,10 @@ extern "C" {
 
 struct ReportList;
 
-/* error reporting */
+/** Error reporting: convert BKE_report (#ReportList) reports into python errors.
+ *
+ * \param clear: When `true`, #BKE_reports_free is called on the given `reports`, which should
+ * then be considered as 'freed' data and not used anymore. */
 short BPy_reports_to_error(struct ReportList *reports, PyObject *exception, bool clear);
 /**
  * A version of #BKE_report_write_file_fp that uses Python's stdout.

source/blender/python/intern/bpy_interface_run.cc

@@ -281,11 +281,9 @@ static bool bpy_run_string_impl(bContext *C,
 
     ReportList *wm_reports = CTX_wm_reports(C);
     if (wm_reports) {
-      BLI_movelisttolist(&wm_reports->list, &reports.list);
-    }
-    else {
-      BKE_reports_clear(&reports);
+      BKE_reports_move_to_reports(wm_reports, &reports);
     }
+    BKE_reports_free(&reports);
   }
   else {
     Py_DECREF(retval);

source/blender/python/intern/bpy_library_load.cc

@@ -575,6 +575,8 @@ static PyObject *bpy_lib_exit(BPy_Library *self, PyObject * /*args*/)
   BKE_blendfile_link_append_context_free(lapp_context);
   BKE_main_id_tag_all(bmain, LIB_TAG_PRE_EXISTING, false);
 
+  BKE_reports_free(&self->reports);
+
   Py_RETURN_NONE;
 }
 

source/blender/python/intern/bpy_library_write.cc

@@ -187,17 +187,18 @@ static PyObject *bpy_lib_write(BPy_PropertyRNA *self, PyObject *args, PyObject *
 
   if (retval) {
     BKE_reports_print(&reports, RPT_ERROR_ALL);
-    BKE_reports_clear(&reports);
     ret = Py_None;
     Py_INCREF(ret);
   }
   else {
-    if (BPy_reports_to_error(&reports, PyExc_IOError, true) == 0) {
+    if (BPy_reports_to_error(&reports, PyExc_IOError, false) == 0) {
       PyErr_SetString(PyExc_IOError, "Unknown error writing library data");
     }
     ret = nullptr;
   }
 
+  BKE_reports_free(&reports);
+
 finally:
 
   /* clear all flags for ID's added to the store (may run on error too) */

source/blender/python/intern/bpy_operator.cc

@@ -263,6 +263,7 @@ static PyObject *pyop_call(PyObject * /*self*/, PyObject *args)
 
       BKE_reports_clear(reports);
       if ((reports->flag & RPT_FREE) == 0) {
+        BKE_reports_free(reports);
         MEM_freeN(reports);
       }
       else {

source/blender/python/intern/bpy_rna.cc

@@ -8792,7 +8792,8 @@ static int bpy_class_call(bContext *C, PointerRNA *ptr, FunctionRNA *func, Param
       BKE_reports_init(&reports_temp, reports->flag | RPT_PRINT_HANDLED_BY_OWNER);
       reports_temp.storelevel = reports->storelevel;
       BPy_errors_to_report(&reports_temp);
-      BLI_movelisttolist(&reports->list, &reports_temp.list);
+      BKE_reports_move_to_reports(reports, &reports_temp);
+      BKE_reports_free(&reports_temp);
     }
 
     /* Also print in the console for Python. */
@@ -9006,11 +9007,12 @@ static PyObject *pyrna_register_class(PyObject * /*self*/, PyObject *py_class)
     if (!has_error) {
       BPy_reports_write_stdout(&reports, error_prefix);
     }
-    BKE_reports_clear(&reports);
     if (has_error) {
+      BKE_reports_free(&reports);
       return nullptr;
     }
   }
+  BKE_reports_free(&reports);
 
   /* Python errors validating are not converted into reports so the check above will fail.
    * the cause for returning nullptr will be printed as an error */