Compiler strangely trying to call another function (constructor) than intended

Question

Hiho,

I have implemented a singleton class in C++ which has got a problem with an initialization within its constructor where I try to initialize a member with a custom constructor but instead the compiler thinks I want to call the default constructor (without arguments) and (of course) can't find it as I don't need a default constructor for that class.

Here is the code:

class CionTokenTypes final {
private:
    CionTokenTypes();

    TokenType init_tt(TokenType token_type, bool skipped = false);

    std::vector<TokenType> m_all_token_types;
    std::vector<TokenType> m_skipped_token_types;

    static const CionTokenTypes c_instance;

public:
    CionTokenTypes(CionTokenTypes const&) = delete;
    CionTokenTypes(CionTokenTypes &&) = delete;

    static CionTokenTypes const& get_instance();

    std::vector<TokenType> const& get_all() const;
    std::vector<TokenType> const& get_skipped() const;

    TokenType const my_custom_token_type;
};

Here is the source file:

const CionTokenTypes CionTokenTypes::c_instance = {};

TokenType CionTokenTypes::init_tt(
    TokenType token_type,
    bool skipped
) {
    m_all_token_types.push_back(token_type);
    if (skipped) {
        m_skipped_token_types.push_back(token_type);
    }
    return std::move(token_type);
}

CionTokenTypes const& CionTokenTypes::get_instance() {
    return c_instance;
}

std::vector<TokenType> const& CionTokenTypes::get_all() const {
    return m_all_token_types;
}

std::vector<TokenType> const& CionTokenTypes::get_skipped() const {
    return m_skipped_token_types;
}

CionTokenTypes::CionTokenTypes():
    m_all_token_types{},
    m_skipped_token_types{},
    my_custom_token_type{init_tt({"bracket: closing bracket ]", "\\]"})}
{}

And you might also want to see the TokenType class:

class TokenType final {
public:
    enum class MatchType : uint8_t {
        non_greedy,
        greedy
    };

    TokenType(
        std::string const& name,
        std::string const& regex = "",
        TokenTypeStore store_type = TokenTypeStore::empty,
        MatchType match_type = MatchType::non_greedy);

    TokenType() = delete;
    TokenType(TokenType const& other) = default;
    TokenType(TokenType && other) = default;
    TokenType & operator=(TokenType const& other) = default;
    TokenType & operator=(TokenType && other) = default;
};

And its source file:

TokenType::TokenType(
    std::string const& name,
    std::string const& regex,
    TokenTypeStore store_type,
    TokenType::MatchType match_type
):
    m_data{
        std::make_shared<TokenType::Data>(
            name,
            regex,
            store_type,
            match_type
        )
    }
{}

I have cut out the not important parts as these files would have been just too huge for a complete paste at StackOverflow.

The compiler error:

/home/robbepop/coding/c++/projects/cion/src/token/cion_token_types.cpp: In constructor ‘cion::CionTokenTypes::CionTokenTypes()’:
/home/robbepop/coding/c++/projects/cion/src/token/cion_token_types.cpp:207:69: error: use of deleted function ‘cion::TokenType::TokenType()’
   closing_brack  {init_tt({"bracket: closing bracket ]"    , "\\]"})}
                                                                     ^
In file included from /home/robbepop/coding/c++/projects/cion/include/token/cion_token_types.hpp:4:0,
                 from /home/robbepop/coding/c++/projects/cion/src/token/cion_token_types.cpp:1:
/home/robbepop/coding/c++/projects/cion/include/token/token_type.hpp:56:3: note: declared here
   TokenType() = delete;
   ^
/home/robbepop/coding/c++/projects/cion/src/token/cion_token_types.cpp:207:69: error: use of deleted function ‘cion::TokenType::TokenType()’
   closing_brack  {init_tt({"bracket: closing bracket ]"    , "\\]"})}
                                                                     ^
In file included from /home/robbepop/coding/c++/projects/cion/include/token/cion_token_types.hpp:4:0,
                 from /home/robbepop/coding/c++/projects/cion/src/token/cion_token_types.cpp:1:
/home/robbepop/coding/c++/projects/cion/include/token/token_type.hpp:56:3: note: declared here
   TokenType() = delete;
   ^
src/CMakeFiles/cion_compiler.dir/build.make:1066: recipe for target 'src/CMakeFiles/cion_compiler.dir/token/cion_token_types.cpp.o' failed
make[2]: *** [src/CMakeFiles/cion_compiler.dir/token/cion_token_types.cpp.o] Error 1
CMakeFiles/Makefile2:75: recipe for target 'src/CMakeFiles/cion_compiler.dir/all' failed
make[1]: *** [src/CMakeFiles/cion_compiler.dir/all] Error 2
Makefile:76: recipe for target 'all' failed
make: *** [all] Error 2
make  62.10s user 5.93s system 98% cpu 1:08.80 total

I hope you can help me as I really don't know why the compiler thinks that I want to call the default constructor instead of my custom one ...

I finally found out what's the source of this strange compiler error:

It is in fact really strange. The source of the problem was that the header file declared about one hundred members of the CionTokenTypes class but they got initialized in the wrong order and some got even left out in the source file of the class which resulted in the error that the compiler can't find the default constructor for the last member.

So I guess this confusing was mainly caused by a poor error handling for this situation.

Answer 1

Could be wrong, as I do not seem to have enough of your code to properly reproduce the error in ideone.

From the looks of things your are attempting to invoke the default constructor of TokenType at line 210 and because none is being automatically generated by the compiler, you get an error. It is not being generated because you have declared another constructor and the rules of C++ then skip generation of the default constructor.

Solutions include (one of):

1. You weren't supposed to be calling a default constructor, so investigate line 210 and stop that.
2. You actually did want a default constructor, add the line TokenType() = default; to your TokenType struct.