Check full AST for functions and classes

[Artalus]

Current implementation simply compares the text of definitions, instead of their semantic content and underlying types, which doesn't allow detecting cases like these:

using ViolatingAlias = float;
class SubtleViolationClass {
public:
	ViolatingAlias x;
	void fun() { std::cout << x << '\n'; }
};

//b.cpp
using ViolatingAlias = std::string;
class SubtleViolationClass {
public:
	ViolatingAlias x;
	void fun() { std::cout << x << '\n'; }
};

The possible way for comparing statements (function bodies) is present here.
Problem: stored Stmt* pointers invalidate somewhere after clang::ast_matchers::MatchFinder::MatchCallback's void run(const clang::ast_matchers::MatchFinder::MatchResult &result) exit.
Maybe matchers are a wrong approach and I need to switch to other ways of traversing AST.

[Artalus]

Clue from mailing list.