Method sanitize

src/ast/ast_typedecl.cpp:1617–1623

    }

    void TypeDecl::sanitize ( ) {
        isExplicit = false;
        explicitConst = false;
        if ( firstType ) firstType->sanitize();
        if ( secondType ) secondType->sanitize();
        for ( auto & argT : argTypes ) argT->sanitize();
    }

    bool isSameExactNullType ( const TypeDeclPtr & a, const TypeDeclPtr & b ) {
        if ( a && b ) {