anonymous structs?

Did you use "rgb_t" anywhere else in this module?

If not, then the waring is valaid. You can either delete that union declaration or keep it and ignore the warning.

If "rgb_t" is used elsewhere, then CCE is incorrect. You can still ignore the warning.

A struct declaration can have a type "tag" or can be anonymous. But it must have an actual declaration name in order to create something.

   struct <tag> { float r, g, b; } <declaration>;

Without the <declaration>, this line contributes nothing to the union and the r, g, and b elements will not be accessible from the union.

If you were to declare a union as

union rgb_t myUnion;

then you would access the elements using

myUnion.asArray[0] = 1.1;
myUnion.asArray[1] = 2.2;
myUnion.asArray[2] = 3.3;

but there is no way to access the r, g, and b.without the declaration. If instead you use

union rgb_t
{
   struct { float r, g, b; } asStruct;
   float asArray[3];
};

then you can get to those elements as

myUnion.asStruct.r = 4.4;
myUnion.asStruct.g = 5.5;
myUnion.asStruct.b = 6.6;

Hi, thanks for the replies.

I think I wasn't very clear in describing my problem. In IAR (and gcc, msvc) I can do this:

union rgb_t
{
  struct { float r, g, b; };
  float asArray[3];
};

rgb_t color = {1,1,1};
color.r = .5;
float green = color.g;
float blue = color.asArray[2];

I often see this [non-standard] feature referred to as "anonymous structs/unions" which is of course misleading. Google tells me that the gcc docs refer to it as "Unnamed struct/union fields within structs/unions."

For some reason I thought CCE used some flavor of gcc, but I guess not. Not a terribly big deal, but it's a very handy extension to the language.. sigh.

Anonymous Struct/union is not allow in C Language .

But IAR has used their own Language Extensions by default which is allow to use anonymous struct/union. 

And in gcc, you can use anonymous struct/union too by add  "-fms-extensions" in Makefiles.

For more details you can read from  http://gcc.gnu.org/onlinedocs/gcc-3.4.5/gcc.pdf ,

Chapter 5: Extensions to the C Language Family , 

5.53  Unnamed struct/union fields within structs/unions.

Good Luck!!

Hi, thanks for the reply, but the question was about CCE, not gcc.  (And I mentioned in my second post that, as you say, this is possible in IAR and gcc.)