MacOS Intel: Fix a crash in the choose-fonts kitten when displaying previews of variable fonts

Looks like a bug in Py_BuildValue for s# values on that platform. Workaround by
constructing the string directly and passing to to Py_BuildValue.

Fixes #7734

docs/changelog.rst

@@ -79,6 +79,8 @@ Detailed list of changes
 
 - Allow specifying that the :opt:`cursor shape for unfocused windows <cursor_shape_unfocused>` should remain unchanged (:pull:`7728`)
 
+- MacOS Intel: Fix a crash in the choose-fonts kitten when displaying previews of variable fonts (:iss:`7734`)
+
 0.36.0 [2024-08-17]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

kitty/font-names.c

@@ -325,8 +325,8 @@ read_fvar_font_table(const uint8_t *table, size_t table_len, PyObject *name_look
         const double minimum = next32, def = next32, maximum = next32;
         p = (uint16_t*)(pos + 16);
         int32_t flags = next, strid = next;
-        PyObject *axis = Py_BuildValue("{sd sd sd ss# sO sN}",
-            "minimum", minimum, "maximum", maximum, "default", def, "tag", pos, 4,
+        PyObject *axis = Py_BuildValue("{sd sd sd sN sO sN}",
+            "minimum", minimum, "maximum", maximum, "default", def, "tag", PyUnicode_FromStringAndSize((const char*)pos, 4),
             "hidden", (flags & 1) ? Py_True : Py_False, "strid", get_best_name(name_lookup_table, strid)
         ); if (!axis) return NULL;
         PyTuple_SET_ITEM(axes, i, axis);