Dealing with headers that use #error

[Dr15Jones]

When doing code migrations, it is useful to allow headers which are not supposed to be used (or possible not used directly) to use the c pre-processor directive #error. The difficulty is our header file consistency check reports these errors. These errors are intentional so should not cause a failure of the header file consistency (in fact, it would be even better if the header did NOT report an error that it caused a failure in the test).

We should determine a way to keep these cases from causing the header consistency from reporting a problem.

[Dr15Jones]

assign core

[cmsbuild]

New categories assigned: core

@Dr15Jones,@makortel,@smuzaffar you have been requested to review this Pull request/Issue and eventually sign? Thanks

[cmsbuild]

cms-bot internal usage

[cmsbuild]

A new Issue was created by @Dr15Jones.

@Dr15Jones, @antoniovilela, @makortel, @mandrenguyen, @rappoccio, @sextonkennedy, @smuzaffar can you please review it and eventually sign/assign? Thanks.

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[Dr15Jones]

@makortel and I had a quick discussion on this issue and came up with two possible ideas

• When running the header file consistency check, use a particular -D directive. Any header file using #error would use a #ifndef on that directive to NOT issue the error in that case. This is easy to maintain but intrusive to the header and would not help catch a case where the error SHOULD go off but does not.
• We add another step to the header consistency check that uses a list of headers that are supposed to issue errors. If those headers do issue an error the check does not report anything wrong. If they fail to generate an error the checker does mark that as a failure.

[Dr15Jones]

@smuzaffar your thoughts on this would be very appreciated.

[smuzaffar]

@Dr15Jones , instead of keeping a hard coded list of headers to ignore, can we just ignore any header which generates : error: #error message ? I can update header consistency check to ignore such headers .

[Dr15Jones]

Seems reasonable to me.

[Dr15Jones]

@smuzaffar Do #warning also lead to failure in the header consistency checker?

[smuzaffar]

@smuzaffar Do #warning also lead to failure in the header consistency checker?

No. scram just tries to compile a header and if compiler generates any error then scram treats it as failure. So #warning should not lead to failure

[smuzaffar]

cms-sw/cms-bot#2427 fixes bot code to not report headers which explicitly use #error
IB headers checks are also fixed to ignore such headers and latest header consistency checks are passed for 15.0.X

[smuzaffar]

+core

I guess we can close this issue

[cmsbuild]

This issue is fully signed and ready to be closed.

[makortel]

@cmsbuild, please close