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0

On Windows uint16_t is just a typedef of unsigned short (from VS2017 stdint.h):

typedef unsigned short uint16_t;

But on QNX6 with GCC uint16_t from stdint.h refers to _Uint16t:

typedef _Uint16t uint16_t;

which is declared in includesyscompiler_gnu.h as following:

typedef unsigned int _GCC_ATTR_ALIGN_u16t __attribute__((__mode__(__HI__)));
typedef _GCC_ATTR_ALIGN_u16t _Uint16t __attribute__((__aligned__(2)));

What's the reason to make uint16_t aligned in that case?

The question is came from the code below:

 using T = uint16_t;
 std::map<T, unsigned char> m;

Which gives me a warning:

warning: ignoring attributes on template argument 'T aka short unsigned int' 
[-Wignored-attributes]

Should I switch back to using T = unsigned short; to prevent such a warning?

c++ gnu memory-alignment qnx

share|improve this question

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What version of QNX are you using? What is the gcc version?
  
  – Red.Wave
  Mar 28 at 13:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Red.Wave I cross-compile application on Windows via gcc 5.5 for QNX6.5
  
  – αλεχολυτ
  Mar 28 at 13:09
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Can you remove the "-Wignored-attributes" switch from compile options?
  
  – Red.Wave
  Mar 28 at 14:02
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Red.Wave sure, but I don't see a reason to do so. I would like to know why uint16_t is aligned on QNX.
  
  – αλεχολυτ
  Mar 29 at 12:27
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  A realtime OS with a claim on speed.
  
  – Red.Wave
  Mar 29 at 13:55
  

  
  
  
  

add a comment | 

0

On Windows uint16_t is just a typedef of unsigned short (from VS2017 stdint.h):

typedef unsigned short uint16_t;

But on QNX6 with GCC uint16_t from stdint.h refers to _Uint16t:

typedef _Uint16t uint16_t;

which is declared in includesyscompiler_gnu.h as following:

typedef unsigned int _GCC_ATTR_ALIGN_u16t __attribute__((__mode__(__HI__)));
typedef _GCC_ATTR_ALIGN_u16t _Uint16t __attribute__((__aligned__(2)));

What's the reason to make uint16_t aligned in that case?

The question is came from the code below:

 using T = uint16_t;
 std::map<T, unsigned char> m;

Which gives me a warning:

warning: ignoring attributes on template argument 'T aka short unsigned int' 
[-Wignored-attributes]

Should I switch back to using T = unsigned short; to prevent such a warning?

c++ gnu memory-alignment qnx

share|improve this question

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What version of QNX are you using? What is the gcc version?
  
  – Red.Wave
  Mar 28 at 13:01
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Red.Wave I cross-compile application on Windows via gcc 5.5 for QNX6.5
  
  – αλεχολυτ
  Mar 28 at 13:09
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Can you remove the "-Wignored-attributes" switch from compile options?
  
  – Red.Wave
  Mar 28 at 14:02
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Red.Wave sure, but I don't see a reason to do so. I would like to know why uint16_t is aligned on QNX.
  
  – αλεχολυτ
  Mar 29 at 12:27
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  A realtime OS with a claim on speed.
  
  – Red.Wave
  Mar 29 at 13:55
  

  
  
  
  

add a comment | 

On Windows uint16_t is just a typedef of unsigned short (from VS2017 stdint.h):

typedef unsigned short uint16_t;

But on QNX6 with GCC uint16_t from stdint.h refers to _Uint16t:

typedef _Uint16t uint16_t;

which is declared in includesyscompiler_gnu.h as following:

typedef unsigned int _GCC_ATTR_ALIGN_u16t __attribute__((__mode__(__HI__)));
typedef _GCC_ATTR_ALIGN_u16t _Uint16t __attribute__((__aligned__(2)));

What's the reason to make uint16_t aligned in that case?

The question is came from the code below:

 using T = uint16_t;
 std::map<T, unsigned char> m;

Which gives me a warning:

warning: ignoring attributes on template argument 'T aka short unsigned int' 
[-Wignored-attributes]

Should I switch back to using T = unsigned short; to prevent such a warning?

c++ gnu memory-alignment qnx

share|improve this question

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges

typedef unsigned short uint16_t;

typedef _Uint16t uint16_t;

typedef unsigned int _GCC_ATTR_ALIGN_u16t __attribute__((__mode__(__HI__)));
typedef _GCC_ATTR_ALIGN_u16t _Uint16t __attribute__((__aligned__(2)));

 using T = uint16_t;
 std::map<T, unsigned char> m;

share|improve this question

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges

share|improve this question

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges

asked Mar 27 at 8:23

αλεχολυταλεχολυτ

2,07411 gold badge1717 silver badges5151 bronze badges