[C++] RSDK::Matrix multiplication operator breaks build with Linux/gcc-c++ on STL >= 23

[Jds2ce]

Mentioning Linux/gcc because this seemed to work just fine on Windows/MSVC last time I checked. I could be wrong though
Fedora - gcc version 15.2.1 20250808 (Red Hat 15.2.1-1) (GCC)

friend inline Matrix operator*(Matrix &lhs, Matrix &rhs)
{
    Matrix dest;
    Matrix::Multiply(&dest, &lhs, &rhs);
    return dest;
}

error: cannot bind non-const lvalue reference of type ‘RSDK::Matrix&’ to an rvalue of type ‘RSDK::Matrix’

cmake_minimum_required(VERSION 3.20)
project(RSSav2)

set(CMAKE_CXX_STANDARD 23)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

if (CMAKE_COMPILER_IS_GNUCC)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fpermissive")
endif ()

set(GAME_NAME "Source" CACHE STRING "The game directory to look into")
set(GAME_OUTPUT_NAME "Game" CACHE STRING "The name of the built library")

add_compile_definitions(GAME_CUSTOMLINKLOGIC)

option(WITH_RSDK "Whether or not to build with RSDKv5. Defaults to true" OFF) #ON)
option(GAME_STATIC "Whether or not to build the game as a static library." $<BOOL:$<IF:WITH_RSDK,ON,OFF>>)

if (NOT DEFINED GAME_STATIC)
    if (WIN32)
        set(GAME_STATIC OFF)
    elseif (UNIX)
        set(GAME_STATIC OFF)
    else ()
        set(GAME_STATIC ON)
    endif ()
endif ()

option(ORIGINS_FIRST_RELEASE "" OFF)
if (ORIGINS_FIRST_RELEASE)
    set(ORIGINS_PREPLUS ON)
else ()
    option(ORIGINS_PREPLUS "" OFF)
endif ()

if (NOT ORIGINS_PREPLUS)
    set(GAME_VERSION 6 CACHE STRING "The game version to use. Defaults to 6 == Last Steam release")
else ()
    set(GAME_VERSION 3 CACHE STRING "The game version to use. Defaults to 3 == Last pre-plus release")
endif ()

find_path(GAMEAPI
    NAMES
    C
    CPP

    HINTS
    ${CMAKE_CURRENT_SOURCE_DIR}/dependencies
    ${CMAKE_SOURCE_DIR}/dependencies

    PATHS
    ${CMAKE_CURRENT_SOURCE_DIR}
    ${CMAKE_CURRENT_SOURCE_DIR}/..

    PATH_SUFFIXES
    GameAPI
    RSDKv5-GameAPI

    NO_DEFAULT_PATH
    NO_CMAKE_FIND_ROOT_PATH
)

if (GAMEAPI)
    message(STATUS "Found GameAPI for ${GAME_NAME}: ${GAMEAPI}")
else ()
    message(FATAL_ERROR "GameAPI not found for ${GAME_NAME}. Clone it in the dependencies.")
endif ()

option(GAME_INCLUDE_EDITOR "Whether or not to include editor functions. Defaults to true" ON)
option(GAME_INCREMENTAL_BUILD "Whether or not to build all objects separately (for quicker dev-->build iterations). Defaults to false." OFF)

if (GAME_INCREMENTAL_BUILD)
    include(${GAME_NAME}/Objects/Objects.cmake)
    set(GAME_SOURCES
        ${GAMEAPI}/CPP/GameAPI/Game.cpp
        ${GAME_NAME}/Game.cpp
        ${GENERATED_SOURCES}
    )
else ()
    set(GAME_SOURCES
        ${GAMEAPI}/CPP/GameAPI/Game.cpp
        ${GAME_NAME}/RSSav2.cxx
        ${GAME_NAME}/Objects/All.cpp
    )
endif ()

if (GAME_STATIC)
    add_library(${GAME_NAME} STATIC ${GAME_SOURCES})
else ()
    add_library(${GAME_NAME} SHARED ${GAME_SOURCES})
endif ()

target_include_directories(${GAME_NAME} PRIVATE
    ${GAMEAPI}/CPP/
    ${GAME_NAME}/
    ${GAME_NAME}/Objects/
)

if (WIN32)
    target_compile_definitions(${GAME_NAME} PRIVATE _CRT_SECURE_NO_WARNINGS)
endif ()

if (APPLE)
    set_target_properties(${GAME_NAME} PROPERTIES PREFIX "")
endif ()

set_target_properties(${GAME_NAME} PROPERTIES OUTPUT_NAME ${GAME_OUTPUT_NAME})

if (WITH_RSDK)
    set(RSDK_PATH dependencies/RSDKv5 CACHE STRING "The path to look for RSDKv5 if using WITH_RSDK.")

    add_subdirectory(${RSDK_PATH})

    if (GAME_STATIC)
        target_include_directories(RetroEngine PRIVATE ${GAME_NAME}/)
        target_link_libraries(RetroEngine ${GAME_NAME})
    endif ()
else ()
    set(RETRO_REVISION 3 CACHE STRING "What revision to compile for. Defaults to v5U = 3")

    option(RETRO_MOD_LOADER "Enables or disables the mod loader." ON)
    set(RETRO_MOD_LOADER_VER 2 CACHE STRING "Sets the mod loader version. Defaults to latest")

    target_compile_definitions(${GAME_NAME} PRIVATE
        RETRO_REVISION=${RETRO_REVISION}
        RETRO_USE_MOD_LOADER=$<BOOL:${RETRO_MOD_LOADER}>
        RETRO_MOD_LOADER_VER=${RETRO_MOD_LOADER_VER}
        GAME_INCLUDE_EDITOR=$<BOOL:${GAME_INCLUDE_EDITOR}>
        ORIGINS_PREPLUS=$<BOOL:${ORIGINS_PREPLUS}>
        ORIGINS_FIRST_RELEASE=$<BOOL:${ORIGINS_FIRST_RELEASE}>
        GAME_VERSION=${GAME_VERSION}
    )
endif ()

if (MSVC)
    target_link_options(${GAME_NAME} PRIVATE /OPT:NOICF)
endif ()