From 937d799aa019610fe03f2a5526cfd8d96229cca6 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Thu, 3 Apr 2025 13:58:26 +1100
Subject: [PATCH 1/5] win32: build without threads but still with implicit sys

Discovered while trying to test #17601 since the build failed with:

perllib.c(62): error C2039: 'cur_tid': is not a member of 'interp_intern'
...\perl\win32\win32.h(566): note: see declaration of 'interp_intern'
perllib.c(68): error C2039: 'cur_tid': is not a member of 'interp_intern'
...\perl\win32\win32.h(566): note: see declaration of 'interp_intern'
---
 win32/perllib.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/win32/perllib.c b/win32/perllib.c
index 1200a351bea9..a787e231ec56 100644
--- a/win32/perllib.c
+++ b/win32/perllib.c
@@ -51,6 +51,7 @@ xs_init(pTHX)
 void
 win32_checkTLS(PerlInterpreter *host_perl)
 {
+#ifdef USE_ITHREADS
 /* GCurThdId() is lightweight, but b/c of the ctrl-c/signals sometimes firing
   in other random WinOS threads, that make the TIDs go out of sync.
   This isn't always an error, although high chance of a SEGV in the next
@@ -67,6 +68,13 @@ win32_checkTLS(PerlInterpreter *host_perl)
         }
         host_perl->Isys_intern.cur_tid = tid;
     }
+#else
+    dTHX;
+    if (host_perl != my_perl) {
+        int *nowhere = NULL;
+        abort();
+    }
+#endif
 }
 
 EXTERN_C void

From 8d33f0f797698ffae210a9716b81fb2e9588d031 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Mon, 7 Apr 2025 13:11:07 +1000
Subject: [PATCH 2/5] perldelta for Win32 -Dusethreads builds fix

---
 pod/perldelta.pod | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index baf1d278054a..875de427f34c 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -330,9 +330,10 @@ L</Modules and Pragmata> section.
 
 =over 4
 
-=item XXX-some-platform
+=item Win32
 
-XXX
+Fix builds with C<USE_IMP_SYS> defined but C<USE_ITHREADS> not
+defined.
 
 =back
 

From 29a96c3aff3c3512692deb0950e3fd7526cd2037 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Tue, 8 Apr 2025 09:49:23 +1000
Subject: [PATCH 3/5] win32_checkTLS: eliminate no longer used variable

This was used rather questionably to crash perl, stopping
in the debugger if there is one, but that was removed in 7bd379e8.
---
 win32/perllib.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/win32/perllib.c b/win32/perllib.c
index a787e231ec56..c85016a08c54 100644
--- a/win32/perllib.c
+++ b/win32/perllib.c
@@ -63,7 +63,6 @@ win32_checkTLS(PerlInterpreter *host_perl)
     if(tid != host_perl->Isys_intern.cur_tid) {
         dTHX; /* heavyweight */
         if (host_perl != my_perl) {
-            int *nowhere = NULL;
             abort();
         }
         host_perl->Isys_intern.cur_tid = tid;
@@ -71,7 +70,6 @@ win32_checkTLS(PerlInterpreter *host_perl)
 #else
     dTHX;
     if (host_perl != my_perl) {
-        int *nowhere = NULL;
         abort();
     }
 #endif

From 8ecfcfb2b1073865a1980871c9595be7ae1f4963 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Wed, 9 Apr 2025 09:19:05 +1000
Subject: [PATCH 4/5] win32_checkTLS: add a panic message and break into the
 debugger

if there is one.

Previously this would exit silently and mysteriously, and unlike
POSIX-likes abort() doesn't generally break into the debugger on
Win32.
---
 win32/perllib.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/win32/perllib.c b/win32/perllib.c
index c85016a08c54..cb20c0a3f2c2 100644
--- a/win32/perllib.c
+++ b/win32/perllib.c
@@ -48,6 +48,13 @@ xs_init(pTHX)
 
 #include "perlhost.h"
 
+#define PANIC_THREAD_ID_MSG "panic: thread id mismatch\n"
+
+#define panic_thread_id() \
+    (void)WriteFile(GetStdHandle(STD_ERROR_HANDLE),         \
+        PANIC_THREAD_ID_MSG, sizeof(PANIC_THREAD_ID_MSG)-1, \
+        NULL, NULL)
+
 void
 win32_checkTLS(PerlInterpreter *host_perl)
 {
@@ -63,6 +70,8 @@ win32_checkTLS(PerlInterpreter *host_perl)
     if(tid != host_perl->Isys_intern.cur_tid) {
         dTHX; /* heavyweight */
         if (host_perl != my_perl) {
+            panic_thread_id();
+            DebugBreak();
             abort();
         }
         host_perl->Isys_intern.cur_tid = tid;
@@ -70,6 +79,8 @@ win32_checkTLS(PerlInterpreter *host_perl)
 #else
     dTHX;
     if (host_perl != my_perl) {
+        panic_thread_id();
+        DebugBreak();
         abort();
     }
 #endif

From 3ff321eb48d6a3d15a9fdc90df33bc77ff71cdea Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Wed, 9 Apr 2025 15:21:20 +1000
Subject: [PATCH 5/5] win32_checkTLS(): nothing to do without at least
 multiplicity

---
 win32/perllib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/win32/perllib.c b/win32/perllib.c
index cb20c0a3f2c2..efae2d817b8d 100644
--- a/win32/perllib.c
+++ b/win32/perllib.c
@@ -76,7 +76,7 @@ win32_checkTLS(PerlInterpreter *host_perl)
         }
         host_perl->Isys_intern.cur_tid = tid;
     }
-#else
+#elif defined(PERL_MULTIPLICITY)
     dTHX;
     if (host_perl != my_perl) {
         panic_thread_id();