UI: improve errors when evaluating a number button fails

Showing the Python error without any explanation is often
not enough information and doesn't hint that the error was in the
user input.

The error report from a invalid expression such as '..1' used to be:
   ('invalid syntax', ('<string>', 1, 1, '..1'))

Now reads:
   Error evaluating number, see Info editor for details: invalid syntax

Address issue raised by T78913.

3 files changed, 44 insertions, 20 deletions

diff --git a/source/blender/python/intern/bpy_capi_utils.c b/source/blender/python/intern/bpy_capi_utils.c
index 0befd6aad2f..27eea80f1f6 100644
--- a/source/blender/python/intern/bpy_capi_utils.c
+++ b/source/blender/python/intern/bpy_capi_utils.c
@@ -97,7 +97,10 @@ void BPy_reports_write_stdout(const ReportList *reports, const char *header)
   }
 }
 
-bool BPy_errors_to_report_ex(ReportList *reports, const bool use_full, const bool use_location)
+bool BPy_errors_to_report_ex(ReportList *reports,
+                             const char *error_prefix,
+                             const bool use_full,
+                             const bool use_location)
 {
   PyObject *pystring;
 
@@ -124,6 +127,11 @@ bool BPy_errors_to_report_ex(ReportList *reports, const bool use_full, const boo
     return 0;
   }
 
+  if (error_prefix == NULL) {
+    /* Not very helpful, better than nothing. */
+    error_prefix = "Python";
+  }
+
   if (use_location) {
     const char *filename;
     int lineno;
@@ -135,17 +143,22 @@ bool BPy_errors_to_report_ex(ReportList *reports, const bool use_full, const boo
 
     BKE_reportf(reports,
                 RPT_ERROR,
-                TIP_("%s\nlocation: %s:%d\n"),
+                TIP_("%s: %s\nlocation: %s:%d\n"),
+                error_prefix,
                 _PyUnicode_AsString(pystring),
                 filename,
                 lineno);
 
     /* Not exactly needed. Useful for developers tracking down issues. */
-    fprintf(
-        stderr, TIP_("%s\nlocation: %s:%d\n"), _PyUnicode_AsString(pystring), filename, lineno);
+    fprintf(stderr,
+            TIP_("%s: %s\nlocation: %s:%d\n"),
+            error_prefix,
+            _PyUnicode_AsString(pystring),
+            filename,
+            lineno);
   }
   else {
-    BKE_report(reports, RPT_ERROR, _PyUnicode_AsString(pystring));
+    BKE_reportf(reports, RPT_ERROR, "%s: %s", error_prefix, _PyUnicode_AsString(pystring));
   }
 
   Py_DECREF(pystring);
@@ -154,5 +167,5 @@ bool BPy_errors_to_report_ex(ReportList *reports, const bool use_full, const boo
 
 bool BPy_errors_to_report(ReportList *reports)
 {
-  return BPy_errors_to_report_ex(reports, true, true);
+  return BPy_errors_to_report_ex(reports, NULL, true, true);
 }
diff --git a/source/blender/python/intern/bpy_capi_utils.h b/source/blender/python/intern/bpy_capi_utils.h
index 97344ce1326..2d654336f8f 100644
--- a/source/blender/python/intern/bpy_capi_utils.h
+++ b/source/blender/python/intern/bpy_capi_utils.h
@@ -39,8 +39,10 @@ char *BPy_enum_as_string(const struct EnumPropertyItem *item);
 short BPy_reports_to_error(struct ReportList *reports, PyObject *exception, const bool clear);
 void BPy_reports_write_stdout(const struct ReportList *reports, const char *header);
 bool BPy_errors_to_report_ex(struct ReportList *reports,
+                             const char *error_prefix,
                              const bool use_full,
                              const bool use_location);
+bool BPy_errors_to_report_brief_with_prefix(struct ReportList *reports, const char *error_prefix);
 bool BPy_errors_to_report(struct ReportList *reports);
 
 /* TODO - find a better solution! */
diff --git a/source/blender/python/intern/bpy_interface.c b/source/blender/python/intern/bpy_interface.c
index c40b2ded8ff..f91afa414ce 100644
--- a/source/blender/python/intern/bpy_interface.c
+++ b/source/blender/python/intern/bpy_interface.c
@@ -617,8 +617,11 @@ void BPY_DECREF_RNA_INVALIDATE(void *pyob_ptr)
 /**
  * \return success
  */
-bool BPY_execute_string_as_number(
-    bContext *C, const char *imports[], const char *expr, const bool verbose, double *r_value)
+bool BPY_execute_string_as_number(bContext *C,
+                                  const char *imports[],
+                                  const char *expr,
+                                  const char *report_prefix,
+                                  double *r_value)
 {
   PyGILState_STATE gilstate;
   bool ok = true;
@@ -637,8 +640,8 @@ bool BPY_execute_string_as_number(
   ok = PyC_RunString_AsNumber(imports, expr, "<expr as number>", r_value);
 
   if (ok == false) {
-    if (verbose) {
-      BPy_errors_to_report_ex(CTX_wm_reports(C), false, false);
+    if (report_prefix != NULL) {
+      BPy_errors_to_report_ex(CTX_wm_reports(C), report_prefix, false, false);
     }
     else {
       PyErr_Clear();
@@ -656,7 +659,7 @@ bool BPY_execute_string_as_number(
 bool BPY_execute_string_as_string_and_size(bContext *C,
                                            const char *imports[],
                                            const char *expr,
-                                           const bool verbose,
+                                           const char *report_prefix,
                                            char **r_value,
                                            size_t *r_value_size)
 {
@@ -674,8 +677,8 @@ bool BPY_execute_string_as_string_and_size(bContext *C,
   ok = PyC_RunString_AsStringAndSize(imports, expr, "<expr as str>", r_value, r_value_size);
 
   if (ok == false) {
-    if (verbose) {
-      BPy_errors_to_report_ex(CTX_wm_reports(C), false, false);
+    if (report_prefix != NULL) {
+      BPy_errors_to_report_ex(CTX_wm_reports(C), false, false, report_prefix);
     }
     else {
       PyErr_Clear();
@@ -687,12 +690,15 @@ bool BPY_execute_string_as_string_and_size(bContext *C,
   return ok;
 }
 
-bool BPY_execute_string_as_string(
-    bContext *C, const char *imports[], const char *expr, const bool verbose, char **r_value)
+bool BPY_execute_string_as_string(bContext *C,
+                                  const char *imports[],
+                                  const char *expr,
+                                  const char *report_prefix,
+                                  char **r_value)
 {
   size_t value_dummy_size;
   return BPY_execute_string_as_string_and_size(
-      C, imports, expr, verbose, r_value, &value_dummy_size);
+      C, imports, expr, report_prefix, r_value, &value_dummy_size);
 }
 
 /**
@@ -700,8 +706,11 @@ bool BPY_execute_string_as_string(
  *
  * \return success
  */
-bool BPY_execute_string_as_intptr(
-    bContext *C, const char *imports[], const char *expr, const bool verbose, intptr_t *r_value)
+bool BPY_execute_string_as_intptr(bContext *C,
+                                  const char *imports[],
+                                  const char *expr,
+                                  const char *report_prefix,
+                                  intptr_t *r_value)
 {
   BLI_assert(r_value && expr);
   PyGILState_STATE gilstate;
@@ -717,8 +726,8 @@ bool BPY_execute_string_as_intptr(
   ok = PyC_RunString_AsIntPtr(imports, expr, "<expr as intptr>", r_value);
 
   if (ok == false) {
-    if (verbose) {
-      BPy_errors_to_report_ex(CTX_wm_reports(C), false, false);
+    if (report_prefix != NULL) {
+      BPy_errors_to_report_ex(CTX_wm_reports(C), report_prefix, false, false);
     }
     else {
       PyErr_Clear();