WIP: AthenaKernel+StoreGate: Change storeName to std::string_view

Change the StoreID::storeName helper to return a std::string_view and adjust all handles to accept a std::string_view instead of const std::string&. This allows the helper function to become constexpr. A few explicit std::string conversions had to be added for calls that do not support std::string_view, i.e. construction of ServiceHandles.

I did this mostly to see if string_view could be useful not because there was a problem in the current code. Also I am not sure this actually makes a difference in compiled (optimized) code.

So I would appreciate comments from @ssnyder @leggett @tsulaia.

Jenkins please retry a build

This merge request affects 3 packages:

• Control/AthenaKernel
• Control/IOVSvc
• Control/StoreGate

Adding @ssnyder as watcher

added Core master labels

Thanks Frank.

Yeah, i doubt there would be a noticible difference.

I guess with a change like this, one needs to be careful that one doesn't introduce dangling references to deleted objects (where you used to make a copy). I don't think that's an issue here, though.

If you're going to go ahead with this, it would probably also be a good idea to extend the Gaudi handles so that they can take a string_view, so we don't need the explicit conversions.

CI Result FAILURE (hash 483f5a6f)

	Athena	AthSimulation	AnalysisBase	AthGeneration
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 2, warnings 6
AthSimulation: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 16764]

@fwinkl this WIP MR has been inactive for 2 months, can this move forward or be closed? Thanks! -- L1

closed