Re: [arm-gnu] int32_t != int?

[Kishore <kitts.mailinglists@xxxxxxxxx>]

I think i now understand the reason here. For arm int32_t is a typedef of long 
and not of int. C/C++ allow promoting and not "demoting". Here, int32_t which 
is of type long cannot be demoted to int. Providing a constructor for long 
solves the issue.

On Wednesday 15 Jul 2009 6:37:21 pm Kishore wrote:
> On Wednesday 15 Jul 2009 9:47:32 am Mark Mitchell wrote:
> > Kishore wrote:
> > > Why is g++ not making the right choice and implicitly considering
> > > int32_t to be an ordinary int? I can construct a simple example to
> > > demonstrate this if needed.
> >
> > Yes, you should post an example.
>
> The following is the sample code
> test.cpp :
> #include <inttypes.h>
>
> class MyClass
> {
>   public:
>   int64_t m_val;
>   MyClass(int val){m_val = val;}
>   MyClass(unsigned int val){m_val = (int64_t)val;}
>
>   //The following two constructors give an error when used with native g++
> compiler Their absence is a problem for arm-none-eabi-g++ //  
> MyClass(int32_t val){m_val = val;}
> //   MyClass(uint32_t val){m_val = (int64_t)val;}
> };
>
>
> main()
> {
>   int32_t value = 45;
>   MyClass myClass(value);
>   while(1);
> }
>
> -----------------------------
> Native g++ wont compile with those two constructors and arm-none-eabi-g++
> will not compile without them! Here is the output.
>
> kishore@Lucifer:~$ g++ test.cpp
> test.cpp:12: error: ‘MyClass::MyClass(int32_t)’ cannot be overloaded
> test.cpp:8: error: with ‘MyClass::MyClass(int)’
> test.cpp:13: error: ‘MyClass::MyClass(uint32_t)’ cannot be overloaded
> test.cpp:9: error: with ‘MyClass::MyClass(unsigned int)’
> kishore@Lucifer:~$ export PATH=$PATH:~/Downloads/arm-2009q1/bin
> kishore@Lucifer:~$ arm-none-eabi-g++ test.cpp
> /home/kishore/Downloads/arm-2009q1/bin/../lib/gcc/arm-none-eabi/4.3.3/../..
>/../../arm-none-eabi/bin/ld: warning: cannot find entry symbol _start;
> defaulting to 00008018 //Here i comment out the two fixed width
> constructors
> kishore@Lucifer:~$ arm-none-eabi-g++ test.cpp
> test.cpp: In function 'int main()':
> test.cpp:20: error: call of overloaded 'MyClass(int32_t&)' is ambiguous
> test.cpp:9: note: candidates are: MyClass::MyClass(unsigned int)
> test.cpp:8: note:                 MyClass::MyClass(int)
> test.cpp:5: note:                 MyClass::MyClass(const MyClass&)
> kishore@Lucifer:~$
>
> Please ignore the linker warning here. I have not explicitly mentioned a
> liker script for this example.

-- 
Cheers!
Kishore