From 7f0d3ab724051cae90bf42ff6b0388895232d85f Mon Sep 17 00:00:00 2001
From: FakeSohi <megaraquazah@gmail.com>
Date: Tue, 21 Apr 2026 20:31:53 -0400
Subject: [PATCH] fft.h: include <cstring> for std::memcpy

std::memcpy is used in RealFFT<>::fft and ::ifft but <cstring> is not
included directly. Older libstdc++ versions pulled it in transitively
via other headers, but GCC 13+ (e.g. MSYS2 UCRT64) does not, producing:

  error: 'memcpy' is not a member of 'std'; did you mean 'wmemcpy'?

Adding the explicit include fixes the build on stricter toolchains
without affecting platforms that previously compiled by accident.
---
 fft.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fft.h b/fft.h
index 80b559b..d24bbae 100644
--- a/fft.h
+++ b/fft.h
@@ -4,6 +4,7 @@
 #include <complex>
 #include <vector>
 #include <cmath>
+#include <cstring>
 
 #if defined(__FAST_MATH__) && (__apple_build_version__ >= 16000000) && (__apple_build_version__ <= 16000099) && !defined(SIGNALSMITH_IGNORE_BROKEN_APPLECLANG)
 #	error Apple Clang 16.0.0 generates incorrect SIMD for ARM. If you HAVE to use this version of Clang, turn off -ffast-math.