Fix: Py_BuildValue should accept spaces in dict spec

Author: fangerer

graalpython/com.oracle.graal.python.cext/src/modsupport.c

@@ -467,12 +467,14 @@ MUST_INLINE static PyObject* _PyTruffle_BuildValue(const char* format, va_list v
             break;
         case ':':
         case ',':
+        case ' ':
             if (v->prev == NULL) {
                 PyErr_SetString(PyExc_SystemError, "':' without '{' in Py_BuildValue");
             }
             break;
         default:
-            fprintf(stderr, "error: unsupported format starting at %d : '%s'\n", format_idx, format);
+            PyErr_SetString(PyExc_SystemError, "bad format char passed to Py_BuildValue");
+            return NULL;
         }
         c = format[++format_idx];
     }

graalpython/com.oracle.graal.python.test/src/tests/cpyext/test_modsupport.py

@@ -428,3 +428,14 @@ def compile_module(self, name):
         cmpfunc=unhandled_error_compare
     )
 
+    test_Py_BuildValue = CPyExtFunction(
+        lambda args: {args[1]: args[2], args[3]: args[4]},
+        lambda: (
+            ('{O:O, O:O}', 'hello', 'world', 'foo', 'bar'),
+        ),
+        resultspec="O",
+        argspec="sOOOO",
+        arguments=["char* fmt", "PyObject* a", "PyObject* b", "PyObject* c", "PyObject* d"],
+        cmpfunc=unhandled_error_compare
+    )
+