Add function-first finalizers (#416)

README.md

@@ -189,6 +189,9 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `Uninitialized` and `uninitialized` with corresponding `Array` constructors ([#24652]).
 
+* `finalizer` accepts the finalizer to run as the first argument and the object to be finalized
+  as the second ([#24605])
+
 ## Renaming
 
 
@@ -363,5 +366,6 @@ includes this fix. Find the minimum version from there.
 [#24282]: https://github.com/JuliaLang/julia/issues/24282
 [#24372]: https://github.com/JuliaLang/julia/issues/24372
 [#24459]: https://github.com/JuliaLang/julia/issues/24459
+[#24605]: https://github.com/JuliaLang/julia/issues/24605
 [#24652]: https://github.com/JuliaLang/julia/issues/24652
 [#24657]: https://github.com/JuliaLang/julia/issues/24657

src/Compat.jl

@@ -818,6 +818,14 @@ end
     export Uninitialized, uninitialized
 end
 
+if VERSION < v"0.7.0-DEV.2562"
+    import Base: finalizer
+    finalizer(f::Function, o) = finalizer(o, f)
+    finalizer(f::Ptr{Void}, o) = finalizer(o, f)
+    finalizer(f::Ptr{Void}, o::Ptr{Void}) = invoke(finalizer, Tuple{Ptr{Void}, Any}, f, o)
+    finalizer(f::Ptr{Void}, o::Function) = invoke(finalizer, Tuple{Ptr{Void}, Any}, f, o)
+end
+
 include("deprecated.jl")
 
 end # module Compat

test/runtests.jl

@@ -900,7 +900,6 @@ let a = [1 0 0; 0 1 0; 0 0 1]
     @test SparseMatrixCSC{Complex128,Int8}(I, 3, 2)::SparseMatrixCSC{Complex128,Int8} == a[:,1:2]
 end
 
-
 # 0.7.0-DEV.2581
 @test isa(Vector(uninitialized, 2), Vector{Any})
 @test isa(Vector{Float64}(uninitialized, 2), Vector{Float64})
@@ -909,6 +908,17 @@ end
 @test isa(Array{Float64}(uninitialized, 2, 2), Matrix{Float64})
 @test isa(Array{Float64,3}(uninitialized, 2, 2, 2), Array{Float64,3})
 
+# 0.7
+let A = [1]
+    local x = 0
+    finalizer(a->(x+=1), A)
+    finalize(A)
+    @test x == 1
+    A = 0
+    gc(); gc()
+    @test x == 1
+end
+
 if VERSION < v"0.6.0"
     include("deprecated.jl")
 end