c++gccgcc-warningprecompiled-headers

How can I avoid `#pragma once in main file` in GCC when using precompiled headers?

Here is a minimal example:

// pch.h
#pragma once

#include <iostream>

And I run:

g++ -x c++-header -o pch.h.gch -c pch.hpp

When I run the command, I get

pch.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |

From my understanding, this behavior is intended by GCC after reading their bugzilla bug tracker; so, this is not a bug but a feature.

How can I disable this warning? Is there a warning number or name that I can suppress by adding it as a pragma statement:

#pragma GCC diagnostic ignored "-Wcan-i-set-something-here"
Solution

  • From my understanding, this behavior is intended by GCC

    As far as I can tell, it's a bug.

    How can I disable this warning?

    Unfortunately, it appears that you cannot since the warning cannot be controlled by an option. In my opinion, this is a bug as well.

    You can circumvent the issue by using a header guard instead of #pragma once.