Increase type stability of NoInverse and FunctionWithInverse

Ensures NoInverse and FunctionWithInverse are type-stable for
type/constructor callables.

Author: oschulz

src/inverse.jl

@@ -62,6 +62,8 @@ An instance `NoInverse(f)` signifies that `inverse(f)` is not defined.
 """
 struct NoInverse{F}
     f::F
+    NoInverse{F}(f) where F = new{F}(f)
+    NoInverse(f) = new{Core.Typeof(f)}(f)
 end
 export NoInverse
 

src/setinverse.jl

@@ -11,6 +11,8 @@ Do not construct directly, use [`setinverse(f, invf)`](@ref) instead.
 struct FunctionWithInverse{F,InvF} <: Function
     f::F
     invf::InvF
+    FunctionWithInverse{F, InvF}(f, invf) where {F, InvF} = new{F, InvF}(f, invf)
+    FunctionWithInverse(f, invf) = new{Core.Typeof(f),Core.Typeof(invf)}(f, invf)
 end
 
 

test/test_inverse.jl

@@ -36,6 +36,10 @@ InverseFunctions.inverse(f::Bar) = Bar(inv(f.A))
         @test inverse(inverse(f)) == f
     end
 
+    @test @inferred(inverse(Complex)) isa NoInverse{Type{Complex}}
+    @test @inferred(NoInverse(Complex)) isa NoInverse{Type{Complex}}
+    @test @inferred(NoInverse{Type{Complex}}(Complex)) isa NoInverse{Type{Complex}}
+
     InverseFunctions.test_inverse(inverse, log, compare = ===)
 
     InverseFunctions.test_inverse(!, false)

test/test_setinverse.jl

@@ -5,11 +5,15 @@ using InverseFunctions
 
 
 @testset "setinverse" begin
+    @test @inferred(setinverse(Complex, Real)) isa InverseFunctions.FunctionWithInverse{Type{Complex},Type{Real}}
+    @test @inferred(InverseFunctions.FunctionWithInverse(Complex, Real)) isa InverseFunctions.FunctionWithInverse{Type{Complex},Type{Real}}
+    @test @inferred(InverseFunctions.FunctionWithInverse{Type{Complex},Type{Real}}(Complex, Real)) isa InverseFunctions.FunctionWithInverse{Type{Complex},Type{Real}}
+    InverseFunctions.test_inverse(setinverse(Complex, Real), 4.2)
+
     @test @inferred(setinverse(sin, asin)) === InverseFunctions.FunctionWithInverse(sin, asin)
     @test @inferred(setinverse(sin, setinverse(asin, sqrt))) === InverseFunctions.FunctionWithInverse(sin, asin)
     @test @inferred(setinverse(setinverse(sin, sqrt), asin)) === InverseFunctions.FunctionWithInverse(sin, asin)
     @test @inferred(setinverse(setinverse(sin, asin), setinverse(asin, sqrt))) === InverseFunctions.FunctionWithInverse(sin, asin)
-
     InverseFunctions.test_inverse(setinverse(sin, asin), π/4)
     InverseFunctions.test_inverse(setinverse(asin, sin), 0.5)
 end