Getting "Error: incomplete type is not allowed"...

[dleanjeanz]

...when declare and assign an instance of a user-defined struct in a function. And the struct (theStruct) is not declared in the same header file as the function (theFunction). Like this:

files:
"A.h": declares the struct in a class (theClass)
"A.cpp": implements the struct
"B.h": declares the function
"B.cpp": implements the function, error here

I think making the instance (inst) a reference might solve this. But the instance is assigned to a return value from a function (returnFunc). Like:

void theFunction() {
...
theClass::theStruct inst = returnFunc(...); 
//returnFunc() returns an instance of theStruct
//the error is at 'inst'
...
}

What do you think?

[cire]

The definition of theClass::theStruct must be visible to theFunction.

[dleanjeanz]

Sure it's visible, it's public. I'm getting "incomplete ype is not allowed" error.

[Lachlan Easton]

When you say

"A.h": declares the struct in a class

are you just declaring the struct? ie struct theClass ? If so then you need to define the whole class in A.h (you can define its functions elsewhere).
This is because B.cpp doesn't know what the struct is (it knows it's a struct because you declared it, but not how big it is or what it's members are)

[cire]

dleanjeanz wrote:

Sure it's visible, it's public. I'm getting "incomplete ype is not allowed" error.

I thought I was supplying enough emphasis. Let me add a little more:

cire wrote:

The definition of theClass::theStruct must be visible to theFunction.

A declaration is insufficient.

[dleanjeanz]

OK. I've edited:

class theClass {
...
struct theStruct;
...
}

to

class theClass {
...
struct theStruct {
...
}
...
}

Thanks a lot.

[Owenno]

r