From 63a8fe07ee7226016f9e2edcd829c03236829584 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C3=ABl=20Van=20Canneyt?= <michael@freepascal.org>
Date: Mon, 6 Nov 2023 10:53:57 +0100
Subject: [PATCH] * Avoid access violation, use internalerror instead. See also
 issue #40502

---
 compiler/pgenutil.pas | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/compiler/pgenutil.pas b/compiler/pgenutil.pas
index 5735f39e42..6f2b1062d1 100644
--- a/compiler/pgenutil.pas
+++ b/compiler/pgenutil.pas
@@ -2752,7 +2752,20 @@ uses
               interface is still being parsed and thus the localsymtable is in
               reality the global symtable }
             if pu.u.in_interface then
-              symtablestack.push(pu.u.localsymtable)
+              begin
+                {
+                  MVC: The case where localsymtable is also nil can appear in complex cases and still produce valid code.
+                  In order to allow people in this case to continue, SKIP_INTERNAL20231102 can be defined.
+                  Default behaviour is to raise an internal error.
+                }
+                {$IFDEF SKIP_INTERNAL20231102}
+                if (pu.u.localsymtable<>Nil) then
+                {$ELSE}
+                if (pu.u.localsymtable=Nil) then
+                  internalerror(20231102);
+                {$ENDIF}
+                  symtablestack.push(pu.u.localsymtable);
+              end
             else
               internalerror(200705153)
           else