Make All Types Constant by Default in C++

Question

What is the simplest and least obtrusive way to indicate to the compiler, whether by means of compiler options, #defines, typedefs, or templates, that every time I say T, I really mean T const? I would prefer not to make use of an external preprocessor. Since I don't use the mutable keyword, that would be acceptable to repurpose to indicate mutable state.

Edit: Since the intent of this was mistaken entirely (and since I wasn't around for a few hours to clarify), let me explain. In essence, I just want to know what systems are available for manipulating the type system at compile time. I don't care if this creates nonstandard, bad, unmaintainable, useless code. I'm not going to use it in production. It's just a curiosity.

Potential (suboptimal) solutions so far:

// I presume redefinition of keywords is implementation-defined or illegal.
#define int int const
#define ptr * const
int i(0);
int ptr j(&i);

typedef int const Int;
typedef int const* const Intp;
Int i(0);
Intp j(&i);

template<class T>
struct C { typedef T const type; typedef T const* const ptr; };
C<int>::type i(0);
C<int>::ptr j(&i);

Answer 1

Take an open source C++ compiler and modify it.

I think the main reason for the downvotes is that people think you're trying to modify C++. Tell them instead you're creating a new language called "C-const" as a university project.

Personally I think it's an interesting idea - you can gain all sorts of performance and readability gains from immutable types - just look at most functional languages.

Answer 2

Even if you are able to do this (which I suspect you are not), think about other people reading your code. They are not likely to understand that everything is const and as a result are not likely to understand your code.