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 +++++++
 1 file changed, 7 insertions(+)

(limited to 'configure.ac')

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])
 
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