From aef987dccf26fbe06a9a54f870e59eb1daa7a176 Mon Sep 17 00:00:00 2001 From: "J. Nick Koston" Date: Sun, 22 Mar 2026 12:37:46 -1000 Subject: [PATCH] [core] Fix Callback::create memcpy from function reference (#14995) --- esphome/core/helpers.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/esphome/core/helpers.h b/esphome/core/helpers.h index 43431299de..82c6b3833c 100644 --- a/esphome/core/helpers.h +++ b/esphome/core/helpers.h @@ -1762,7 +1762,10 @@ template struct Callback { // Safe under C++20 (P0593R6): byte copy into aligned storage implicitly // creates objects of implicit-lifetime types (trivially copyable qualifies). Callback cb; // fn and ctx are zero-initialized by default - __builtin_memcpy(&cb.ctx_, &callable, sizeof(DecayF)); + // Decay callable to a local variable first. When F is a function reference + // (e.g. void(&)(int)), &callable would point at machine code, not a pointer variable. + DecayF decayed = std::forward(callable); + __builtin_memcpy(&cb.ctx_, &decayed, sizeof(DecayF)); cb.fn_ = [](void *c, Ts... args) { alignas(DecayF) char buf[sizeof(DecayF)]; __builtin_memcpy(buf, &c, sizeof(DecayF));