From 9a657e1dabc196e60dcf48435d48fb51aef3c60d Mon Sep 17 00:00:00 2001
From: Pip Cet <pipcet@protonmail.com>
Date: Sun, 2 Mar 2025 17:38:35 +0000
Subject: [PATCH] [MPS] Trace backtrace function PDL entries

* src/igc.c (scan_specpdl): Trace bt.function, which might not be
covered by an ambiguous root.
---
 src/igc.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/igc.c b/src/igc.c
index cb9399b6728..ec714cad435 100644
--- a/src/igc.c
+++ b/src/igc.c
@@ -1553,6 +1553,7 @@ scan_specpdl (mps_ss_t ss, void *start, void *end, void *closure)
 	       thread's control stack, or to something in the bytecode
 	       stack.  Both should already be ambiguous roots.  */
 	  case SPECPDL_BACKTRACE:
+	    IGC_FIX12_OBJ (ss, &pdl->bt.function);
 	    break;
 
 #ifdef HAVE_MODULES