Only define methods on SuiteSparse.UMFPACK if GPL libs present

[nickrobinson251]

Fix package on Julia versions built without GPL libraries (i.e. with USE_GPL_LIBS=0)

This is so packages depending on SparseMatricesCSR.jl will still compile, even on Julia versions built without GPL libraries. Prompted by dmlc/XGBoost.jl#157

Before we'd get

julia> using SparseMatricesCSR
[ Info: Precompiling SparseMatricesCSR [a0a7dd2c-ebf4-11e9-1f05-cf50bc540ca1]
ERROR: LoadError: UndefVarError: `UMFPACK` not defined
Stacktrace:
 [1] getproperty(x::Module, f::Symbol)
   @ Base ./Base.jl:31
 [2] top-level scope
   @ ~/repos/SparseMatricesCSR.jl/src/SparseMatrixCSR.jl:143
 [3] include(mod::Module, _path::String)
   @ Base ./Base.jl:456
 [4] include(x::String)
   @ SparseMatricesCSR ~/repos/SparseMatricesCSR.jl/src/SparseMatricesCSR.jl:1
 [5] top-level scope
   @ ~/repos/SparseMatricesCSR.jl/src/SparseMatricesCSR.jl:17
 [6] include
   @ ./Base.jl:456 [inlined]
 [7] include_package_for_output(pkg::Base.PkgId, input::String, depot_path::Vector{String}, dl_load_path::Vector{String}, load_path::Vector{String}, concrete_deps::Vector{Pair{Base.PkgId, UInt128}}, source::Nothing)
   @ Base ./loading.jl:1900
 [8] top-level scope
   @ stdin:2
in expression starting at /Users/nickr/repos/SparseMatricesCSR.jl/src/SparseMatrixCSR.jl:143
in expression starting at /Users/nickr/repos/SparseMatricesCSR.jl/src/SparseMatricesCSR.jl:1
in expression starting at stdin:2
ERROR: Failed to precompile SparseMatricesCSR [a0a7dd2c-ebf4-11e9-1f05-cf50bc540ca1] to "/Users/nickr/.julia/compiled/v1.10/SparseMatricesCSR/jl_iZfEOo".
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] compilecache(pkg::Base.PkgId, path::String, internal_stderr::IO, internal_stdout::IO, keep_loaded_modules::Bool)
   @ Base ./loading.jl:2124
 [3] compilecache
   @ ./loading.jl:2016 [inlined]
 [4] _require(pkg::Base.PkgId, env::String)
   @ Base ./loading.jl:1660
 [5] _require_prelocked(uuidkey::Base.PkgId, env::String)
   @ Base ./loading.jl:1515
 [6] macro expansion
   @ ./loading.jl:1503 [inlined]
 [7] macro expansion
   @ ./lock.jl:267 [inlined]
 [8] require(into::Module, mod::Symbol)
   @ Base ./loading.jl:1466

Now the package compiles as expected

julia> using SparseMatricesCSR
[ Info: Precompiling SparseMatricesCSR [a0a7dd2c-ebf4-11e9-1f05-cf50bc540ca1]

julia>

[nickrobinson251]

@amartinhuertas, might you be able to take a look? thanks!

[amartinhuertas]

Thanks for the PR!

I was not aware of this issue.

The fix that you submitted provenly solves the precompilation error.

However, I wonder whether if- constructs of the type

if Base.USE_GPL_LIBS
....

should also go to other parts of the code to avoid other potential errors. (I agree precompilation is the most annoying).

Whats your view on this?

[nickrobinson251]

i couldn't see any other code paths that would error without GPL libraries -- did you have any in mind?

The lu! codepath now behind Base.USE_GPL_LIBS will be an error, which is why the if check in tests too

e.g given

using SparseMatricesCSR, SparseArrays, LinearAlgebra
Bi = 0;
I = [1,1,2,2,2,3,3];
J = [1,2,1,2,3,2,3];
V = [4.0,1.0,-1.0,4.0,1.0,-1.0,4.0];
CSR = sparsecsr(Val(Bi),I,J,V);

in Julia with GPL libs

julia> fact = lu(CSR);

julia> typeof(fact)
Transpose{Float64, SuiteSparse.UMFPACK.UmfpackLU{Float64, Int64}}

julia> lu!(fact, CSR)
Transpose of SuiteSparse.UMFPACK.UmfpackLU{Float64, Int64}
L factor:
3×3 SparseMatrixCSC{Float64, Int64} with 5 stored entries:
  1.0        ⋅         ⋅
   ⋅        1.0        ⋅
 -0.208333  0.208333  1.0
U factor:
3×3 SparseMatrixCSC{Float64, Int64} with 5 stored entries:
 0.8   ⋅    0.2
  ⋅   0.8  -0.2
  ⋅    ⋅    0.75

whereas without GPL libs

julia> fact = lu(CSR);

julia> typeof(fact)
Transpose{Float64, LU{Float64, SparseMatrixCSC{Float64, Int64}, Vector{Int64}}}

julia> lu!(fact, CSR)
ERROR: MethodError: no method matching lu!(::Transpose{Float64, LU{Float64, SparseMatrixCSC{Float64, Int64}, Vector{Int64}}}, ::SparseMatrixCSR{0, Float64, Int64})

but at least the package and any dependents are now loadable (i.e. now only this one codepath doesn't work without GPL libs, rather than the whole package)

[amartinhuertas]

Ok, thanks for the explanation. Once the tests pass, I will accept the PR.

[codecov-commenter]

Codecov Report

Merging #21 (79a5a6f) into master (dbe71cf) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #21   +/-   ##
=======================================
  Coverage   86.17%   86.17%           
=======================================
  Files           3        3           
  Lines         246      246           
=======================================
  Hits          212      212           
  Misses         34       34           

Impacted Files	Coverage Δ
src/SparseMatrixCSR.jl	86.47% <ø> (ø)

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[nickrobinson251]

Thanks, @amartinhuertas! Would it be possible to get a new patch release of this package which includes this fix please? 🙏

[amartinhuertas]

Yes. Patch release already triggered.

[nickrobinson251]

thanks!