PCH warning after installing SP1 by RobYull

I also have this problem with the following code:


#ifndef chamber_h__
#define chamber_h__

class Chamber
{
public:
    Chamber();
    ~Chamber();

private:

protected:
};

#endif // chamber_h__

Which really makes no sense because there are way more headers and classes in this project, and this is the only one it has a problem with.

Hello RobYull,

Thank for you reporting this issue. This is an duplicate of another internal bug report. We have fixed this internally already, but unfortunately, the bug fix didn't make it into SP1. It would be included in the future releases of VS.

You are quite correct. If the header is not included by any cpp file in your project/solution, you could potentially get a PCH warning. This is because our intellisense engine works with translation units instead of individual files. A translation unit is essentially a c/cpp file and all the header files that were included. When a header file, say x.h, is opened, VS searches the include graph and find a suitable .c/cpp file that includes x.h use that as the translation unit for the intellisense engine. However, if x.h is not found in the include graph (ie. not included by any .c/cpp file in the project), then the intellisense engine will use the header file itself as the translation unit (eg. treating that header file as a .c/cpp file). In that case, the intellisense engine won't be able to generate the iPCH due to the reason described by the error message itself.

As you already know, you can work around this by including the problematic headers in a .c/cpp file.

Thanks,
Alan Chan
Visual C++ Team

Hello RobYull,

Thank for you reporting this issue. This is an duplicate of another internal bug report. We have fixed this internally already, but unfortunately, the bug fix didn't make it into SP1. It would be included in the future releases of VS.

You are quite correct. If the header is not included by any cpp file in your project/solution, you could potentially get a PCH warning. This is because our intellisense engine works with translation units instead of individual files. A translation unit is essentially a c/cpp file and all the header files that were included. When a header file, say x.h, is opened, VS searches the include graph and find a suitable .c/cpp file that includes x.h use that as the translation unit for the intellisense engine. However, if x.h is not found in the include graph (ie. not included by any .c/cpp file in the project), then the intellisense engine will use the header file itself as the translation unit (eg. treating that header file as a .c/cpp file). In that case, the intellisense engine won't be able to generate the iPCH due to the reason described by the error message itself.

As you already know, you can work around this by including the problematic headers in a .c/cpp file.

Thanks,
Alan Chan
Visual C++ Team

I've attached a test case. In the testcase, I found that the error was generated in the header if it was not included by a cpp file. Also I saw the error appear in the cpp file if there were no headers included (files are commented on what seems to work and not work).

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