Same Header File Is Different

Question

Same Header File Is Different

a_unique_name 401

Hello Folks:

Developing on Windows 10, up to date Visual Studio Community 2022, C++.

When building my application I occasionally see this error:

screen_shot

The two header files that Visual studio is complaining about are the same file.

Here is the text of the window. You can see for yourself:

A copy of window_control.h was found in D:\utilities\code\windows_files\headers\window_control.h, but the current source code is different from the version built into D:\utilities\code\windows_files\headers\window_control.h.

If you search for "\utilities\code\windows_files\headers\window_control.h" you'll see this is the same path and file name for the two files that have different source code.

I can go months without seeing this problem, but when it hits it's annoying.

The offending source code can be in different files in different paths.

Restarting Visual Studio usually doesn't resolve the problem and a system reboot is required. Today restarting Visual Studio did resolve the issue and a reboot wasn't required.

Any idea why this is happening?

Thanks
Larry

RLWA32 49,461 Reputation points

2024-05-06T18:18:51.4233333+00:00

Is the build using precompiled headers?
a_unique_name 401 Reputation points

2024-05-06T18:27:27.18+00:00

Thanks Again RLWA32, for the 304th time, at least.:

Is the build using precompiled headers?

Yes

I edited the error message so you can read it.

Thanks

Larry
RLWA32 49,461 Reputation points

2024-05-06T18:47:29.41+00:00

Is there more than one #include statement across multiple sources files for that header? Also, you could try closing the solution and then deleting the contents of the .vs folder except for the .suo file
Minxin Yu 13,501 Reputation points Microsoft External Staff

2024-05-07T01:53:20.78+00:00

Have you ever renamed implementation files (*.c, *.cpp, etc.) to header files?
Try cleaning the project and deleting the .vs files.
a_unique_name 401 Reputation points

2024-05-07T12:24:02.96+00:00

Thanks again RLWA32:

Is there more than one #include statement across multiple sources files for that header?

Yes. It's referred to in 17 header and C++ source files.

This particular header header is part of a utility I've built over the years to work with windows. I have dozens of utilities to facilitate different tasks different applications perform.

This particular file is being modified now. I'm, adding some functions.

Also, you could try closing the solution and then deleting the contents of the .vs folder except for the .suo file

I'll give that a try next time I see this. I hadn't tried it before.

Thanks

Larry
RLWA32 49,461 Reputation points

2024-05-07T12:28:42.1533333+00:00

Since you're using precompiled headers why don't you include that header as part of pch.h or stdafx.h so that you can eliminate the multiple references.
a_unique_name 401 Reputation points

2024-05-07T12:48:59.2466667+00:00

Thanks Minxin Yu:

Have you ever renamed implementation files (*.c, *.cpp, etc.) to header files?

I don't believe that happened recently.

Try cleaning the project and deleting the .vs files.

I'll try deleting .vs next time. I'll want to preserve my bookmarks and breakpoints, which I've recently been informed reside in the .suo file under one of the .vs subfolders.

Thanks

Larry
a_unique_name 401 Reputation points

2024-05-07T13:02:35.46+00:00

Thanks Again RLWA32:

Since you're using precompiled headers why don't you include that header as part of pch.h or stdafx.h so that you can eliminate the multiple references.

I believe precompiled headers is a default setting for every new application or new .cpp file I add to an application.

I seem to get a complaint from the compiler if I forget to add #include "stdafx.h" as a source module's first statement.

Thanks

Larry
RLWA32 49,461 Reputation points

2024-05-07T13:11:29.3733333+00:00

I seen to get a complaint from the compiler if I forget to add #include "stdafx.h" as a source module's first statement.

Yes, that's why you can eliminate the multiple references to window_control.h if you make it a part of the precompiled headers.

I believe precompiled headers is a default setting for every new application or new .cpp file I add to an application.

That depends on how the solution/project was created. It's not always a default.
a_unique_name 401 Reputation points

2024-05-07T17:05:54.54+00:00

Thanks again RLWA32:

My reply just disappeared. It was short so let's try again.

The current situation is that, after restarting Visual Studio, I can build without seeing the warning. Now I'm wondering how I can permanently resolve the issue.

My app's current percompiled header configuration:

Percompiled Header - Use (/Yu)
Percompiled Header File - stdafx.h
Percompiled Header Output File - $(IntDir)$(TargetName).pch

Opening a new Visual Studio session for my window_control utility shows the same percompiled header settings.

I've been doing a little reading, but have some questions.

Is there a difference using stdafx.h and pch.h?

I'm using the IDE.

If I order a Rebuild Solution <CTL><ALT><F7>, should this forge a consistency across the build? It doesn't seem to do so.

If mistakes in my code or Visual Studio configuration are causing this problem, why does the warning go away for months when I restart Visual Studio or reboot my PC?

I appreciate your assistance.

Larry
RLWA32 49,461 Reputation points

2024-05-07T20:31:07.7066667+00:00

Larry,

I have not experienced the Visual Studio message box error in my own projects. So I don't know what could be causing it in yours. I was guessing that there might be some inconsistency between the precompiled headers and the .h file that was driving the error in your projects. That's why I suggested deleting the content of the .vs folder other than the .suo file. Its a brute force technique but it assures that VS will definitely have to rebuild the precompiled headers from scratch. If you can manage to share a sample that reproduces the problem I'd be happy to take a look at it.

Is there a difference using stdafx.h and pch.h?

No, they're just names. Older versions of VS used stdafx.h for the precompiled header. My guess is that Microsoft moved away from that to pch.h because "afx" is closely associated with MFC.

Precompiled header usage requires setting the project PrecompiledHeader propery to Use them and the PrecompiledHeader property for the pch.cpp (or stdafx.cpp) file to Create them.

1 answer

Your answer

RLWA32 49,461 Reputation points

2024-05-06T18:18:51.4233333+00:00

Is the build using precompiled headers?
a_unique_name 401 Reputation points

2024-05-06T18:27:27.18+00:00

Thanks Again RLWA32, for the 304th time, at least.:

Is the build using precompiled headers?

Yes

I edited the error message so you can read it.

Thanks

Larry
RLWA32 49,461 Reputation points

2024-05-06T18:47:29.41+00:00

Is there more than one #include statement across multiple sources files for that header? Also, you could try closing the solution and then deleting the contents of the .vs folder except for the .suo file
Minxin Yu 13,501 Reputation points Microsoft External Staff

2024-05-07T01:53:20.78+00:00

Have you ever renamed implementation files (*.c, *.cpp, etc.) to header files?
Try cleaning the project and deleting the .vs files.
a_unique_name 401 Reputation points

2024-05-07T12:24:02.96+00:00

Thanks again RLWA32:

Is there more than one #include statement across multiple sources files for that header?

Yes. It's referred to in 17 header and C++ source files.

This particular header header is part of a utility I've built over the years to work with windows. I have dozens of utilities to facilitate different tasks different applications perform.

This particular file is being modified now. I'm, adding some functions.

Also, you could try closing the solution and then deleting the contents of the .vs folder except for the .suo file

I'll give that a try next time I see this. I hadn't tried it before.

Thanks

Larry
RLWA32 49,461 Reputation points

2024-05-07T12:28:42.1533333+00:00

Since you're using precompiled headers why don't you include that header as part of pch.h or stdafx.h so that you can eliminate the multiple references.
a_unique_name 401 Reputation points

2024-05-07T12:48:59.2466667+00:00

Thanks Minxin Yu:

Have you ever renamed implementation files (*.c, *.cpp, etc.) to header files?

I don't believe that happened recently.

Try cleaning the project and deleting the .vs files.

I'll try deleting .vs next time. I'll want to preserve my bookmarks and breakpoints, which I've recently been informed reside in the .suo file under one of the .vs subfolders.

Thanks

Larry
a_unique_name 401 Reputation points

2024-05-07T13:02:35.46+00:00

Thanks Again RLWA32:

Since you're using precompiled headers why don't you include that header as part of pch.h or stdafx.h so that you can eliminate the multiple references.

I believe precompiled headers is a default setting for every new application or new .cpp file I add to an application.

I seem to get a complaint from the compiler if I forget to add #include "stdafx.h" as a source module's first statement.

Thanks

Larry
RLWA32 49,461 Reputation points

2024-05-07T13:11:29.3733333+00:00

I seen to get a complaint from the compiler if I forget to add #include "stdafx.h" as a source module's first statement.

Yes, that's why you can eliminate the multiple references to window_control.h if you make it a part of the precompiled headers.

I believe precompiled headers is a default setting for every new application or new .cpp file I add to an application.

That depends on how the solution/project was created. It's not always a default.
a_unique_name 401 Reputation points

2024-05-07T17:05:54.54+00:00

Thanks again RLWA32:

My reply just disappeared. It was short so let's try again.

The current situation is that, after restarting Visual Studio, I can build without seeing the warning. Now I'm wondering how I can permanently resolve the issue.

My app's current percompiled header configuration:

Percompiled Header - Use (/Yu)
Percompiled Header File - stdafx.h
Percompiled Header Output File - $(IntDir)$(TargetName).pch

Opening a new Visual Studio session for my window_control utility shows the same percompiled header settings.

I've been doing a little reading, but have some questions.

Is there a difference using stdafx.h and pch.h?

I'm using the IDE.

If I order a Rebuild Solution <CTL><ALT><F7>, should this forge a consistency across the build? It doesn't seem to do so.

If mistakes in my code or Visual Studio configuration are causing this problem, why does the warning go away for months when I restart Visual Studio or reboot my PC?

I appreciate your assistance.

Larry
RLWA32 49,461 Reputation points

2024-05-07T20:31:07.7066667+00:00

Larry,

I have not experienced the Visual Studio message box error in my own projects. So I don't know what could be causing it in yours. I was guessing that there might be some inconsistency between the precompiled headers and the .h file that was driving the error in your projects. That's why I suggested deleting the content of the .vs folder other than the .suo file. Its a brute force technique but it assures that VS will definitely have to rebuild the precompiled headers from scratch. If you can manage to share a sample that reproduces the problem I'd be happy to take a look at it.

Is there a difference using stdafx.h and pch.h?

No, they're just names. Older versions of VS used stdafx.h for the precompiled header. My guess is that Microsoft moved away from that to pch.h because "afx" is closely associated with MFC.

Precompiled header usage requires setting the project PrecompiledHeader propery to Use them and the PrecompiledHeader property for the pch.cpp (or stdafx.cpp) file to Create them.

Answer 1

a_unique_name 401

This was supposed to be a question for RLWA32.

It disappeared so I re-asked.

I don't seem to be able to erase it, so please ignore.

Larry

a_unique_name 401 Reputation points

2024-05-07T17:30:06.9966667+00:00

One more thing RLWA32:

Yes, that's why you can eliminate the multiple references to window_control.h if you make it a part of the precompiled headers.

I'm confused by this comment.

Doesn't any .cpp file that uses a resource in my window_control utility need to include "#include <window_control.h>"?

Thanks

Larry

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Same Header File Is Different

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