Remove base_ring methods returning Union{}

[fingolfin]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 40.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 88.14%. Comparing base (c43dcc7) to head (5045133).

Files with missing lines	Patch %	Lines
src/antic/nf_elem.jl	0.00%	1 Missing ⚠️
src/flint/fmpz.jl	0.00%	1 Missing ⚠️
src/flint/fq.jl	0.00%	1 Missing ⚠️
src/flint/fq_default.jl	0.00%	1 Missing ⚠️
src/flint/fq_nmod.jl	0.00%	1 Missing ⚠️
src/flint/gfp_elem.jl	0.00%	1 Missing ⚠️
src/flint/gfp_fmpz_elem.jl	0.00%	1 Missing ⚠️
src/flint/padic.jl	0.00%	1 Missing ⚠️
src/flint/qadic.jl	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2148      +/-   ##
==========================================
- Coverage   88.15%   88.14%   -0.02%     
==========================================
  Files          99       99              
  Lines       37053    37038      -15     
==========================================
- Hits        32665    32646      -19     
- Misses       4388     4392       +4     

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[fingolfin]

Apparently this breaks tests in Hecke and Oscar.

In Hecke:

Error in testset QuadForm/Lattices.jl:
Error During Test at /home/runner/.julia/packages/Hecke/e3v2R/test/QuadForm/Lattices.jl:164
  Test threw exception
  Expression: R != base_ring(base_ring(L))
  MethodError: no method matching base_ring(::ZZRing)

which looks like a weird test to me to begin with?

The one in OSCAR is in the Galois groups code (ping @fieker)

SubfieldLattice: Error During Test at /home/runner/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/test/runtests.jl:38
  Got exception outside of a @test
  MethodError: no method matching base_ring(::AbsSimpleNumField)
  
  Closest candidates are:
    base_ring(::FpMatrix)
     @ Nemo ~/work/Nemo.jl/Nemo.jl/src/flint/gfp_fmpz_mat.jl:85
    base_ring(::ZZCliffordOrder)
     @ Oscar ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/CliffordAlgOrd/src/CliffordOrder.jl:410
    base_ring(::FqMPolyRing)
     @ Nemo ~/work/Nemo.jl/Nemo.jl/src/flint/fq_default_mpoly.jl:19
    ...
  
  Stacktrace:
    [1] Oscar.SubfieldLattice_Module.SubfieldLattice(K::AbsSimpleNumField, G::Oscar.GaloisGrp.GaloisCtx{Hecke.qAdicRootCtx})
      @ Oscar.SubfieldLattice_Module ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/src/Subfields.jl:43
    [2] _subfields(K::AbsSimpleNumField; pStart::Int64, prime::Int64)
      @ Oscar.SubfieldLattice_Module ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/src/Subfields.jl:348
    [3] _subfields
      @ ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/src/Subfields.jl:333 [inlined]
    [4] subfield_lattice(K::AbsSimpleNumField)
      @ Oscar.SubfieldLattice_Module ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/src/Subfields.jl:492
    [5] macro expansion
      @ ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/test/runtests.jl:41 [inlined]
    [6] macro expansion
      @ /opt/hostedtoolcache/julia/1.10.10/x64/share/julia/stdlib/v1.10/Test/src/Test.jl:1577 [inlined]
    [7] top-level scope
      @ ~/work/Nemo.jl/Nemo.jl/oscar-dev/Oscar/experimental/GaloisGrp/test/runtests.jl:39

[fingolfin]

So this is breaking. @fieker will look into adjusting the GaloisGrp code.