Fix indexing for 0D views

[jishnub]

This fixes #128 going by the discussion in julia#37274 and in the spirit of #196.

Now

julia> a = OffsetArray(1:3, 0:2);

julia> b = @view a[0];

julia> b[]
1

julia> b[1]
1

[codecov]

Codecov Report

Merging #197 (0b76276) into master (1263513) will decrease coverage by 0.70%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master     #197      +/-   ##
==========================================
- Coverage   98.93%   98.23%   -0.71%     
==========================================
  Files           5        5              
  Lines         283      284       +1     
==========================================
- Hits          280      279       -1     
- Misses          3        5       +2     

Impacted Files	Coverage Δ
src/OffsetArrays.jl	97.90% <66.66%> (-1.03%)	⬇️
src/axes.jl	100.00% <0.00%> (ø)

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[timholy]

Can we just put this fix in Base? Changing ::OffsetVector to ::AbstractVector? I don't see anything OffsetArrays-specific about this fix.

[jishnub]

Yes the fix should go to Base, this PR is to ensure correct behavior on older versions of julia

[jishnub]

Crossref : julia#39404

[timholy]

Sounds good. Let's wait for that to merge and then add this only on older Julia versions. The risk of method ambiguities seems low in this case, but if we don't have to...

[timholy]

Is it weird that codecov flags compute_linindex as untested?

[jishnub]

Indeed, I don't really understand how this works. Since imposing the version bound seems to have upset codecov, is it that the coverage is being reported by the test on nightly?

[johnnychen94]

My best guess is the first coverage upload in a short period, which happens to be the Julia latest(1 minute) due to a large number of invalidation fixes. If we want it to be predictable, then we could add a version check in our CI settings:

OffsetArrays.jl/.github/workflows/UnitTest.yml

Lines 61 to 63 in 97cef1a

	- uses: codecov/codecov-action@v1
	with:
	file: lcov.info

[timholy]

Thanks again for fixing this!