#pragma once

Can you point to the documentation that shows support for this?  I don't see it in the 15.12.0 compiler guide.

You are correct that #pragma once does not appear in the compiler manual.  I filed CODEGEN-1678 in the SDOWP system to have this addressed.  Feel free to follow it with the SDOWP link below in my signature.

Thanks and regards,

-George

An internet search on #pragma once returns many links that describe it.  Every compiler that supports it does it the same way.  It intended for use in header files.  An appearance of #pragma once in a header file means that, should the header file be included multiple times, only the first one counts.

Thanks and regards,

-George

We can't seem to get it to work.  We've had to fall back to using include guards.

Please try this simple experiment.  What follows is a header file, and a C source file.

// hdr.h
#pragma once
#warn only see this one time

// src.c
#include "hdr.h"
#include "hdr.h"
int a;

When you compile src.c, it should look similar to this ...

%> armcl src.c
"hdr.h", line 3: warning: #warn directive: only see this one time

Even though hdr.h is included twice, the #warn diagnostic is emitted only once.  What happens when you try this experiment?

Thanks and regards,

-George