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    SubjectRe: [PATCH 8/10] bug.h: Make BUILD_BUG_ON generate compile-time error
    On 09/28/2012 07:32 PM, Josh Triplett wrote:
    > On Fri, Sep 28, 2012 at 06:20:09PM -0500, Daniel Santos wrote:
    >> Negative sized arrays wont create a compile-time error in some cases
    >> starting with gcc 4.4 (e.g., inlined functions), but gcc 4.3 introduced
    >> the error function attribute that will. This patch modifies
    >> BUILD_BUG_ON to behave like BUILD_BUG already does, using the error
    >> function attribute so that you don't have to build the entire kernel to
    >> discover that you have a problem, and then enjoy trying to track it down
    >> from a link-time error.
    > Rather than doing both, and potentially producing two errors for the
    > same issue, how about using __compiletime_error only, and only using the
    > negative-sized array when __compiletime_error has no useful definition?
    >
    > For instance, in compiler.h, when defining __compiletime_error as an
    > empty macro in the fallback case, you could define a
    > __compiletime_error_fallback() macro that declares a negative-sized
    > array; you could then define __compiletime_error_fallback() as an empty
    > macro when it doesn't exist.
    Oh, that's a great idea. That will keep more of the compiler's details
    in compiler*.h.

    Daniel


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