Hi,

The short C++ excerpt provided below causes DMC to bail out with:

    v3 = v1 + v2;
                ^
int64.cpp(20) : Error: ambiguous type conversion
--- errorlevel 1

I compiled using the command line:

dmc -c -g -mn -WD -L/noi -L/nol int64.cpp

Any idea what might be causing this? The same code compiles fine using
MSVC or GCC.

Best regards,
Gilles


class INT64 {
public:
    __int64         mValue;
public:
    INT64();
    INT64(const INT64 &);
    INT64(__int64);
    // operators
    INT64 &operator =(const INT64 &);
    INT64 &operator =(__int64);
    operator __int64() const { return mValue; }
};

void main()
{
    INT64 v1(2);
    INT64 v2(4);
    INT64 v3;

    v3 = v1 + v2;
}

Well, at a first glance, you should be providing addition operator (along with all the other arithmetic operators). Beyond that, you're going to want to do a lot of handling of integral conversions.

You might want to check out the stlsoft::sinteger64 class (in <stlsoft/64bit_integers.hpp>), from STLSoft (http://stlsoft.org/).

If you're interested, its implementation (and many of the issues surrounding implementing arithmetic user types) is described in Chapter 29 of Imperfect C++ (http://imperfectcplusplus.com/).

Enjoy!


"Gilles Depeyrot" <gsd@dolphin.fr> wrote in message news:e53vpb$1tvs$1@digitaldaemon.com...
> Hi,
>
> The short C++ excerpt provided below causes DMC to bail out with:
>
>     v3 = v1 + v2;
>                 ^
> int64.cpp(20) : Error: ambiguous type conversion
> --- errorlevel 1
>
> I compiled using the command line:
>
> dmc -c -g -mn -WD -L/noi -L/nol int64.cpp
>
> Any idea what might be causing this? The same code compiles fine using MSVC or GCC.
>
> Best regards,
> Gilles
>
>
> class INT64 {
> public:
>     __int64         mValue;
> public:
>     INT64();
>     INT64(const INT64 &);
>     INT64(__int64);
>     // operators
>     INT64 &operator =(const INT64 &);
>     INT64 &operator =(__int64);
>     operator __int64() const { return mValue; }
> };
>
> void main()
> {
>     INT64 v1(2);
>     INT64 v2(4);
>     INT64 v3;
>
>     v3 = v1 + v2;
> }

Hi,

I am quite aware that the code is not ideal and not even complete since I extracted it from a much larger code base that works with other compilers.

My aim was to understand why DMC doesn't compile my code whereas MSVC and GCC both do. AS far as I can tell, the type conversion is not ambiguous as is.

Gilles

Matthew wrote:
> Well, at a first glance, you should be providing addition operator (along with all the other arithmetic operators). Beyond that, you're going to want to do a lot of handling of integral conversions.
> 
> You might want to check out the stlsoft::sinteger64 class (in <stlsoft/64bit_integers.hpp>), from STLSoft (http://stlsoft.org/).
> 
> If you're interested, its implementation (and many of the issues surrounding implementing arithmetic user types) is described in Chapter 29 of Imperfect C++ (http://imperfectcplusplus.com/).
> 
> Enjoy!
> 
> 
> "Gilles Depeyrot" <gsd@dolphin.fr> wrote in message news:e53vpb$1tvs$1@digitaldaemon.com...
>> Hi,
>>
>> The short C++ excerpt provided below causes DMC to bail out with:
>>
>>     v3 = v1 + v2;
>>                 ^
>> int64.cpp(20) : Error: ambiguous type conversion
>> --- errorlevel 1
>>
>> I compiled using the command line:
>>
>> dmc -c -g -mn -WD -L/noi -L/nol int64.cpp
>>
>> Any idea what might be causing this? The same code compiles fine using
>> MSVC or GCC.
>>
>> Best regards,
>> Gilles
>>
>>
>> class INT64 {
>> public:
>>     __int64         mValue;
>> public:
>>     INT64();
>>     INT64(const INT64 &);
>>     INT64(__int64);
>>     // operators
>>     INT64 &operator =(const INT64 &);
>>     INT64 &operator =(__int64);
>>     operator __int64() const { return mValue; }
>> };
>>
>> void main()
>> {
>>     INT64 v1(2);
>>     INT64 v2(4);
>>     INT64 v3;
>>
>>     v3 = v1 + v2;
>> } 
> 
> 

Ok. Sorry if I misunderstood.

Although I like the compiler, my experience is that DMC++ does experience a lot more "weirdies" than others. This is doubtless an artefact of its having a totally separate heritage: IIRC it derives from the first straight-through C++ compiler. (Walter's been around a while.)

90% of the time my approach to its problems is a pragmatic one: I just find workarounds. You'll find the knowledge of such dotted throughout the STLSoft (and other) libraries. When I am able to, I boil it down and submit a report to Walter, who, to his immense credit, generally manages to divine the problem and find the fix in a very short time. Unfortunately, when it cannot be boiled down, workarounds must suffice since Walter, understandably, refuses to try and work on undistilled (and potentially huge and enmeshed) problems. Since DMC++ is not my workaday C++ compiler, sometimes the workaround is simply to define a component as "#if defined(__DMC__) #error Not compatible with DMC++".

Given the apparent simplicity of the code that's causing the problem, I suspect a fix can be found. I again suggest you consult the implementation of stlsoft::sinteger64 for some ideas, since that component works correctly for many compilers, including DMC++.

HTH

Matthew


"Gilles Depeyrot" <gsd@dolphin.fr> wrote in message news:e5gvdb$31ck$1@digitaldaemon.com...
> Hi,
>
> I am quite aware that the code is not ideal and not even complete since I extracted it from a much larger code base that works with other compilers.
>
> My aim was to understand why DMC doesn't compile my code whereas MSVC and GCC both do. AS far as I can tell, the type conversion is not ambiguous as is.
>
> Gilles
>
> Matthew wrote:
>> Well, at a first glance, you should be providing addition operator (along with all the other arithmetic operators). Beyond that, you're going to want to do a lot of handling of integral conversions.
>>
>> You might want to check out the stlsoft::sinteger64 class (in <stlsoft/64bit_integers.hpp>), from STLSoft (http://stlsoft.org/).
>>
>> If you're interested, its implementation (and many of the issues surrounding implementing arithmetic user types) is described in Chapter 29 of Imperfect C++ (http://imperfectcplusplus.com/).
>>
>> Enjoy!
>>
>>
>> "Gilles Depeyrot" <gsd@dolphin.fr> wrote in message news:e53vpb$1tvs$1@digitaldaemon.com...
>>> Hi,
>>>
>>> The short C++ excerpt provided below causes DMC to bail out with:
>>>
>>>     v3 = v1 + v2;
>>>                 ^
>>> int64.cpp(20) : Error: ambiguous type conversion
>>> --- errorlevel 1
>>>
>>> I compiled using the command line:
>>>
>>> dmc -c -g -mn -WD -L/noi -L/nol int64.cpp
>>>
>>> Any idea what might be causing this? The same code compiles fine using MSVC or GCC.
>>>
>>> Best regards,
>>> Gilles
>>>
>>>
>>> class INT64 {
>>> public:
>>>     __int64         mValue;
>>> public:
>>>     INT64();
>>>     INT64(const INT64 &);
>>>     INT64(__int64);
>>>     // operators
>>>     INT64 &operator =(const INT64 &);
>>>     INT64 &operator =(__int64);
>>>     operator __int64() const { return mValue; }
>>> };
>>>
>>> void main()
>>> {
>>>     INT64 v1(2);
>>>     INT64 v2(4);
>>>     INT64 v3;
>>>
>>>     v3 = v1 + v2;
>>> }
>> 

Hi Matthew,

I certainly agree with you but I hope my feedback will help improve DMC. Given Walter's reactivity fixing issues with small testcases, it certainly should ;-)

Gilles

Matthew wrote:
> Ok. Sorry if I misunderstood.
> 
> Although I like the compiler, my experience is that DMC++ does experience a lot more "weirdies" than others. This is doubtless an artefact of its having a totally separate heritage: IIRC it derives from the first straight-through C++ compiler. (Walter's been around a while.)
> 
> 90% of the time my approach to its problems is a pragmatic one: I just find workarounds. You'll find the knowledge of such dotted throughout the STLSoft (and other) libraries. When I am able to, I boil it down and submit a report to Walter, who, to his immense credit, generally manages to divine the problem and find the fix in a very short time. Unfortunately, when it cannot be boiled down, workarounds must suffice since Walter, understandably, refuses to try and work on undistilled (and potentially huge and enmeshed) problems. Since DMC++ is not my workaday C++ compiler, sometimes the workaround is simply to define a component as "#if defined(__DMC__) #error Not compatible with DMC++".
> 
> Given the apparent simplicity of the code that's causing the problem, I suspect a fix can be found. I again suggest you consult the implementation of stlsoft::sinteger64 for some ideas, since that component works correctly for many compilers, including DMC++.