unnamed type definition in parentheses

when I use vc6 to compile a driver.

I get the error:
error C4116: unnamed type definition in parentheses

this is the code that the error point to:
ProbeForRead(Irp->UserBuffer, pIoStackIrp->Parameters.Write.Length, TYPE_ALIGNMENT(char));

what does TYPE_ALIGNMENT(char)) mean, and why it case the error?

1. http://www.google.com/search?sourcei...TYPE_ALIGNMENT

2. From MSDN:

Quote:

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Compiler Warning (level 1) C4116
unnamed type definition in parentheses

A structure, union, or enumerated type with no name was defined in a parenthetical expression. The type definition is meaningless.

In a C function call, the definition has global scope. In a C++ function call, the definition has the same scope as the function being called.

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Quote:

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Originally Posted by VictorN

1. http://www.google.com/search?sourcei...TYPE_ALIGNMENT

2. From MSDN:

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I also want to know why MSDN says it's a "warning" but when I build the code, the IDE prompts me an "error".

Check your project properties: C/C++->General->Treat warnings as errors.

Quote:

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Originally Posted by Nikitozz

Check your project properties: C/C++->General->Treat warnings as errors.

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What I made is a driver,and the project doesn't have that settings.The user mode app is different from driver. I only view the vc6 as a higher editor.