From 243a3be9185412a5a29ba189c77569fa96c85e89 Mon Sep 17 00:00:00 2001
From: Robin Haberkorn <rhaberkorn@fmsbw.de>
Date: Mon, 20 Oct 2025 00:02:34 +0200
Subject: scintilla: use AX_PTRDIFF_ALIASES_INT to check whether ptrdiff_t
 aliases int

* Scintilla had build problems if ptrdiff_t doesn't alias int if it has the
  same storage size (e.g. on NetBSD 10 (armv6)).
* Unfortunately, Neil Hodgson refused to merge my previous Scintilla patches that
  would have fixed the issue at the core.
  See https://groups.google.com/g/scintilla-interest/c/STAv6LgLyCo
* He only agreed to introducing a separate flag to work around the issue
  (`-DPTRDIFF_DOESNT_ALIAS_INT`).
* In order to continue to support all standard C/C++ conforming platforms
  we therefore need a compile-time check to check for the aliasability
  of ptrdiff_t and int.
---
 configure.ac                 |  7 +++++++
 contrib/scintilla            |  2 +-
 m4/ax_ptrdiff_aliases_int.m4 | 16 ++++++++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 m4/ax_ptrdiff_aliases_int.m4

diff --git a/configure.ac b/configure.ac
index 9d5f74d..c0e9939 100644
--- a/configure.ac
+++ b/configure.ac
@@ -101,6 +101,13 @@ AC_PROG_CXX([c++ g++ clang++])
 AX_CXX_COMPILE_STDCXX(17, noext, mandatory)
 AC_CHECK_TOOL(AR, ar)
 
+# If ptrdiff_t does not alias int, we need a workaround
+# in Scintilla.
+AX_PTRDIFF_ALIASES_INT
+if [[ "x$ax_cv_ptrdiff_aliases_int" = "xno" ]]; then
+	SCINTILLA_CXXFLAGS="$SCINTILLA_CXXFLAGS -DPTRDIFF_DOESNT_ALIAS_INT"
+fi
+
 # Whether $CC is Clang
 AM_CONDITIONAL(CLANG, [$CC --version | $GREP -i clang >/dev/null])
 
diff --git a/contrib/scintilla b/contrib/scintilla
index 7c7d684..333dd31 160000
--- a/contrib/scintilla
+++ b/contrib/scintilla
@@ -1 +1 @@
-Subproject commit 7c7d68414f408e83c0b17088d92212fc10883ea4
+Subproject commit 333dd3153850d05a219731dee0b899155442b191
diff --git a/m4/ax_ptrdiff_aliases_int.m4 b/m4/ax_ptrdiff_aliases_int.m4
new file mode 100644
index 0000000..f7175cd
--- /dev/null
+++ b/m4/ax_ptrdiff_aliases_int.m4
@@ -0,0 +1,16 @@
+
+AC_DEFUN([AX_PTRDIFF_ALIASES_INT], [
+	AC_CACHE_CHECK([whether ptrdiff_t aliases int], [ax_cv_ptrdiff_aliases_int], [
+		AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+			@%:@include <stddef.h>
+		]], [[
+			int a = 23;
+			ptrdiff_t *b = &a;
+		]])],
+		[ax_cv_ptrdiff_aliases_int=yes],
+		[ax_cv_ptrdiff_aliases_int=no])
+	])
+	AS_IF([test "x$ax_cv_ptrdiff_aliases_int" = "xyes"], [
+		AC_DEFINE([PTRDIFF_ALIASES_INT], [1], [Whether ptrdiff_t aliases int])
+	])
+])dnl
-- 
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