put chainrules core in a requires block, rm it from deps (#107)

* put chainrules core in a requires block, rm it from deps

* test conditional loading of CRC

Author: vpuri3

Project.toml

@@ -3,19 +3,16 @@ uuid = "621f4979-c628-5d54-868e-fcf4e3e8185c"
 version = "1.3.1"
 
 [deps]
-ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
-
-[weakdeps]
-ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
-
-[extensions]
-AbstractFFTsChainRulesCoreExt = "ChainRulesCore"
+Requires = "ae029012-a4dd-5104-9daa-d747884805df"
 
 [compat]
 ChainRulesCore = "1"
 julia = "^1.0"
 
+[extensions]
+AbstractFFTsChainRulesCoreExt = "ChainRulesCore"
+
 [extras]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 ChainRulesTestUtils = "cdddcdb0-9152-4a09-a978-84456f9df70a"
@@ -25,3 +22,6 @@ Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 
 [targets]
 test = ["ChainRulesCore", "ChainRulesTestUtils", "Random", "Test", "Unitful"]
+
+[weakdeps]
+ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/AbstractFFTs.jl

@@ -7,8 +7,16 @@ export fft, ifft, bfft, fft!, ifft!, bfft!,
 
 include("definitions.jl")
 
-if !isdefined(Base, :get_extension)
-    include("../ext/AbstractFFTsChainRulesCoreExt.jl")
+@static if !isdefined(Base, :get_extension)
+    import Requires
+end
+
+@static if !isdefined(Base, :get_extension)
+    function __init__()
+        Requires.@require ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4" begin
+            include("../ext/AbstractFFTsChainRulesCoreExt.jl")
+        end
+    end
 end
 
 end # module

test/runtests.jl

@@ -2,7 +2,6 @@
 
 using AbstractFFTs
 using AbstractFFTs: Plan
-using ChainRulesTestUtils
 
 using LinearAlgebra
 using Random
@@ -241,6 +240,19 @@ end
 end
 
 @testset "ChainRules" begin
+
+    if isdefined(Base, :get_extension)
+        CRCEXT = Base.get_extension(AbstractFFTs, :AbstractFFTsChainRulesCoreExt)
+        @test isnothing(CRCEXT)
+    end
+
+    using ChainRulesTestUtils
+
+    if isdefined(Base, :get_extension)
+        CRCEXT = Base.get_extension(AbstractFFTs, :AbstractFFTsChainRulesCoreExt)
+        @test !isnothing(CRCEXT)
+    end
+
     @testset "shift functions" begin
         for x in (randn(3), randn(3, 4), randn(3, 4, 5))
             for dims in ((), 1, 2, (1,2), 1:2)