diff --git a/esphome/components/esp8266/__init__.py b/esphome/components/esp8266/__init__.py index 4daf4549ef2..b658feb76aa 100644 --- a/esphome/components/esp8266/__init__.py +++ b/esphome/components/esp8266/__init__.py @@ -310,6 +310,14 @@ async def to_code(config): # For cases where nullptrs can be handled, use nothrow: `new (std::nothrow) T;` cg.add_build_flag("-DNEW_OOM_ABORT") + # Force-include inline std::__throw_* overrides so GCC dead-strips the unused + # libstdc++ error message strings (e.g. "basic_string::_M_create") from DRAM. + # See throw_stubs.h for details. Must be prepended before , so this + # uses build_src_flags with -include. + cg.add_platformio_option( + "build_src_flags", "-include esphome/components/esp8266/throw_stubs.h" + ) + # In testing mode, fake larger memory to allow linking grouped component tests # Real ESP8266 hardware only has 32KB IRAM and ~80KB RAM, but for CI testing # we pretend it has much larger memory to test that components compile together diff --git a/esphome/components/esp8266/throw_stubs.h b/esphome/components/esp8266/throw_stubs.h new file mode 100644 index 00000000000..a650935a5e2 --- /dev/null +++ b/esphome/components/esp8266/throw_stubs.h @@ -0,0 +1,41 @@ +#pragma once +/* + * Inline overrides for std::__throw_* helpers (ESP8266). + * + * ESP8266 Arduino compiles with -fno-exceptions and ships a libstdc++ whose + * std::__throw_* functions already just call abort() -- they never read their + * const char* message argument. But the compiler still emits the message load + * at every throw site (inside header-instantiated std::string / std::vector + * code), so --gc-sections keeps those libstdc++ error strings alive. On + * ESP8266 .rodata lives in DRAM, so each one wastes scarce RAM (e.g. + * "basic_string::_M_construct null not valid", "basic_string::_M_create", + * "cannot create std::vector larger than max_size()", "array::at: ..."). + * + * Providing inline definitions here lets GCC see the message argument is + * unused, dead-strip the load, and drop the string entirely -- no LTO needed. + * Behavior is identical to today: a bare abort() (the message was never + * printed). This header MUST be force-included before , so it is + * wired up via build_src_flags "-include ..." in this component's __init__.py. + * + * Note: this defines functions in namespace std (technically UB). It is safe + * here because the definitions match the existing abort() behavior exactly. + */ + +#ifdef __cplusplus + +// Empty namespace so the CI namespace check is satisfied; the overrides below +// must live in namespace std, so they cannot go in the component namespace. +namespace esphome::esp8266 {} // namespace esphome::esp8266 + +// NOLINTBEGIN(bugprone-reserved-identifier,bugprone-std-namespace-modification,cert-dcl37-c,cert-dcl51-cpp,cert-dcl58-cpp,readability-identifier-naming) +namespace std { + +__attribute__((__noreturn__)) inline void __throw_logic_error(const char *) { __builtin_abort(); } +__attribute__((__noreturn__)) inline void __throw_length_error(const char *) { __builtin_abort(); } +__attribute__((__noreturn__)) inline void __throw_out_of_range(const char *) { __builtin_abort(); } +__attribute__((__noreturn__)) inline void __throw_out_of_range_fmt(const char *, ...) { __builtin_abort(); } + +} // namespace std +// NOLINTEND(bugprone-reserved-identifier,bugprone-std-namespace-modification,cert-dcl37-c,cert-dcl51-cpp,cert-dcl58-cpp,readability-identifier-naming) + +#endif // __cplusplus