From f48b0463dd619642f2d51d74bffeedade950c8d4 Mon Sep 17 00:00:00 2001
From: Jan Wielemaker <jan@swi-prolog.org>
Date: Wed, 6 Nov 2024 13:09:32 +0100
Subject: [PATCH] DEBUG: First print the Prolog stack "safe" on a crash.

This guarantees that the stack is printed, including details on
the clauses involved and progress in each clause.   Next, the
stacks are printed with arguments.   This however may crash if
the crash is caused by corrupt data on the stacks.
---
 src/pl-init.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/pl-init.c b/src/pl-init.c
index 582bb680e9..10cb1ce4e3 100644
--- a/src/pl-init.c
+++ b/src/pl-init.c
@@ -1825,8 +1825,12 @@ printCrashContext(const char *btname)
 	print_backtrace_named("GC");
       }
     }
-    Sdprintf("\n\nPROLOG STACK:\n");
-    PL_backtrace(10, btflags);
+    Sdprintf("\n\nPROLOG STACK (without arguments):\n");
+    PL_backtrace(10, PL_BT_SAFE);
+    if ( !(btflags&PL_BT_SAFE) )
+    { Sdprintf("\n\nPROLOG STACK (with arguments; may crash if data is corrupted):\n");
+      PL_backtrace(10, btflags);
+    }
   }
 
   running = false;