gh-103194: Fix Tkinter’s Tcl value type handling for Tcl 8.7/9.0 (GH-103846)

Some of standard Tcl types were renamed, removed, or no longer
registered in Tcl 8.7/9.0. This change fixes automatic conversion of Tcl
values to Python values to avoid returning a Tcl_Obj where the primary
Python types (int, bool, str, bytes) were returned in older Tcl.

Author: chrstphrchvz

Misc/NEWS.d/next/Library/2023-04-24-05-34-23.gh-issue-103194.GwBwWL.rst

@@ -0,0 +1,4 @@
+Prepare Tkinter for C API changes in Tcl 8.7/9.0 to avoid
+:class:`_tkinter.Tcl_Obj` being unexpectedly returned
+instead of :class:`bool`, :class:`str`,
+:class:`bytearray`, or :class:`int`.

Modules/_tkinter.c

@@ -318,6 +318,7 @@ typedef struct {
     const Tcl_ObjType *BignumType;
     const Tcl_ObjType *ListType;
     const Tcl_ObjType *StringType;
+    const Tcl_ObjType *UTF32StringType;
 } TkappObject;
 
 #define Tkapp_Interp(v) (((TkappObject *) (v))->interp)
@@ -588,14 +589,40 @@ Tkapp_New(const char *screenName, const char *className,
     }
 
     v->OldBooleanType = Tcl_GetObjType("boolean");
-    v->BooleanType = Tcl_GetObjType("booleanString");
-    v->ByteArrayType = Tcl_GetObjType("bytearray");
+    {
+        Tcl_Obj *value;
+        int boolValue;
+
+        /* Tcl 8.5 "booleanString" type is not registered
+           and is renamed to "boolean" in Tcl 9.0.
+           Based on approach suggested at
+           https://core.tcl-lang.org/tcl/info/3bb3bcf2da5b */
+        value = Tcl_NewStringObj("true", -1);
+        Tcl_GetBooleanFromObj(NULL, value, &boolValue);
+        v->BooleanType = value->typePtr;
+        Tcl_DecrRefCount(value);
+
+        // "bytearray" type is not registered in Tcl 9.0
+        value = Tcl_NewByteArrayObj(NULL, 0);
+        v->ByteArrayType = value->typePtr;
+        Tcl_DecrRefCount(value);
+    }
     v->DoubleType = Tcl_GetObjType("double");
+    /* TIP 484 suggests retrieving the "int" type without Tcl_GetObjType("int")
+       since it is no longer registered in Tcl 9.0. But even though Tcl 8.7
+       only uses the "wideInt" type on platforms with 32-bit long, it still has
+       a registered "int" type, which FromObj() should recognize just in case. */
     v->IntType = Tcl_GetObjType("int");
+    if (v->IntType == NULL) {
+        Tcl_Obj *value = Tcl_NewIntObj(0);
+        v->IntType = value->typePtr;
+        Tcl_DecrRefCount(value);
+    }
     v->WideIntType = Tcl_GetObjType("wideInt");
     v->BignumType = Tcl_GetObjType("bignum");
     v->ListType = Tcl_GetObjType("list");
     v->StringType = Tcl_GetObjType("string");
+    v->UTF32StringType = Tcl_GetObjType("utf32string");
 
     /* Delete the 'exit' command, which can screw things up */
     Tcl_DeleteCommand(v->interp, "exit");
@@ -1124,14 +1151,6 @@ FromObj(TkappObject *tkapp, Tcl_Obj *value)
         return PyFloat_FromDouble(value->internalRep.doubleValue);
     }
 
-    if (value->typePtr == tkapp->IntType) {
-        long longValue;
-        if (Tcl_GetLongFromObj(interp, value, &longValue) == TCL_OK)
-            return PyLong_FromLong(longValue);
-        /* If there is an error in the long conversion,
-           fall through to wideInt handling. */
-    }
-
     if (value->typePtr == tkapp->IntType ||
         value->typePtr == tkapp->WideIntType) {
         result = fromWideIntObj(tkapp, value);
@@ -1176,17 +1195,12 @@ FromObj(TkappObject *tkapp, Tcl_Obj *value)
         return result;
     }
 
-    if (value->typePtr == tkapp->StringType) {
+    if (value->typePtr == tkapp->StringType ||
+        value->typePtr == tkapp->UTF32StringType)
+    {
         return unicodeFromTclObj(value);
     }
 
-    if (tkapp->BooleanType == NULL &&
-        strcmp(value->typePtr->name, "booleanString") == 0) {
-        /* booleanString type is not registered in Tcl */
-        tkapp->BooleanType = value->typePtr;
-        return fromBoolean(tkapp, value);
-    }
-
     if (tkapp->BignumType == NULL &&
         strcmp(value->typePtr->name, "bignum") == 0) {
         /* bignum type is not registered in Tcl */