Skip to content

Rename namespace Gaudi::Units to Allen::Units

Marco Clemencicrequested to merge
prepare-gaudi-v40 into master

I can understand why somebody decided to copy SystemOfUnits.h from Gaudi and change the type of the constants from double to float.

What I really do not get is why the constants were kept in the Gaudi::Units namespace risking a conflict with the constant defined in Gaudi... only prevented by using the same include guard in both headers... which made the choice even more dangerous, because which version of the constants is used depends on the order of inclusion.

Now that Gaudi is migrating to #pragma once (gaudi/Gaudi!1747 (merged)), the mistake gets exposed with 2500 errors like:

In file included from ../main/include/Common.h:21,
                 from ../Dumpers/BinaryDumpers/include/Dumpers/Utils.h:26,
                 from ../Dumpers/RootDumpers/src/PrTrackerDumper.cpp:28:
../main/include/SystemOfUnits.h:61:21: error: conflicting declaration 'constexpr const float Gaudi::Units::millimeter'
   61 |     constexpr float millimeter = 1.f;
      |                     ^~~~~~~~~~
In file included from /dependencies/LHCb/InstallArea/x86_64_v2-el9-gcc13-opt/include/Event/MCParticle.h:20,
                 from ../Dumpers/RootDumpers/src/PrTrackerDumper.cpp:12:
/dependencies/Gaudi/InstallArea/x86_64_v2-el9-gcc13-opt/include/GaudiKernel/SystemOfUnits.h:60:22: note: previous declaration as 'constexpr const double Gaudi::Units::millimeter'
   60 |     constexpr double millimeter  = 1.;
      |                      ^~~~~~~~~~

(see https://lhcb-nightlies.web.cern.ch/nightly/lhcb-gaudi-head/4285/Allen/x86_64_v2-el9-gcc13-opt/build)

This MR corrects the mistake by renaming the namespace Gaudi::Units to Allen::Units.

Merge request reports