The other big change that would be beneficial in (?:Obj)?C(?:++)? would be const-by-default, requiring something like `var` for anything that&#x27;s truly a variable, since `mutable` has a specific meaning in (?:Obj)?C++.  It would be consistent with the theme of least-privilege, and allow for more optimizations of one-time and per-loop iteration values.<p>Another great, modern C++ feature: `constexpr` functions, methods and compile-time constants have the potential to put most, but not all, macros out-of-business... Macros are powerful for DRYing C&#x2F;C++ similar code sections which cannot be expressed with templates, lambdas or function pointers, for macro pasting identifiers together and for project configuration management for (ie, kernel hardware support).  Defines also don&#x27;t occupy space but also lose semantic value in debugging because they&#x27;re computed at compile time and spread out wherever they&#x27;re used... debuggers encountering `constexpr`s should offer both the computed value and a way to debug or debug (not program code at all) how that value was constructed: gdb and lldb should be able to handle that with plugins.<p>Here&#x27;s also how we compile most our code, using both gcc and clang, on both stable and head:<p><pre><code>    clang++ -std=c++1[14z] -Weverything -Werror -Wno-c++98-compat -Wno-weak-vtables ...

    g++ -std=c++1[14z] -Wpedantic -Wextra -Werror -Wformat=2 ...
</code></pre>
I would also really like to see C++1[7z] concepts implemented by major compilers, because this will make our code a whole lot simpler by reduce the hacks for runtime and compile-time type checking, and make generic programming much cleaner by being able to constrain requirements via arbitrary bool constexprs.