Compat for Julia #18510, #18484

README.md

@@ -60,6 +60,8 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `@compat @boundscheck checkbounds(...)` rewrites to unconditionally call `checkbounds(...)` in 0.4.  The 0.4-style two-argument form of `@boundscheck` is left unchanged.
 
+* `@compat Nullable(value, hasvalue)` to handle the switch from the `Nullable` `:isnull` field to `:hasvalue` field. [#18510](https://github.com/JuliaLang/julia/pull/18510)
+
 ## Type Aliases
 
 * `String` has undergone multiple changes: in Julia 0.3 it was an abstract type and then got renamed to `AbstractString` in 0.4; in 0.5, `ASCIIString` and `ByteString` were deprecated, and `UTF8String` was renamed to the (now concrete) type `String`.
@@ -83,6 +85,8 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `redirect_stdout`, `redirect_stderr`, and `redirect_stdin` take an optional function as a first argument, `redirect_std*(f, stream)`, so that one may use `do` block syntax (as first available for Julia 0.6).
 
+* `unsafe_get` returns the `:value` field of a `Nullable` object without any null-check and has a generic fallback for non-`Nullable` argument. [#18484](https://github.com/JuliaLang/julia/pull/18484) (Also, `isnull` has a generic fallback for non-`Nullable` argument.)
+
 ## Renamed functions
 
 * `pointer_to_array` and `pointer_to_string` have been replaced with `unsafe_wrap(Array, ...)` and `unsafe_wrap(String, ...)` respectively.

src/Compat.jl

@@ -613,6 +613,9 @@ function _compat(ex::Expr)
         elseif VERSION < v"0.5.0-dev+4340" && length(ex.args) > 3 &&
                 istopsymbol(withincurly(ex.args[1]), :Base, :show)
             ex = rewrite_show(ex)
+        elseif VERSION < v"0.6.0-dev.826" && length(ex.args) == 3 && # julia#18510
+                istopsymbol(withincurly(ex.args[1]), :Base, :Nullable)
+            ex = Expr(:call, f, ex.args[2], Expr(:call, :(Compat._Nullable_field2), ex.args[3]))
         end
         if VERSION < v"0.5.0-dev+4305"
             rewrite_iocontext!(ex)
@@ -1657,4 +1660,23 @@ if VERSION < v"0.5.0-dev+4677"
     Base.cholfact!(A::HermOrSym, T::Type) = cholfact!(A.data, Symbol(A.uplo), T)
 end
 
+# julia#18510
+if VERSION < v"0.6.0-dev.826"
+    _Nullable_field2(x) = !x
+else
+    _Nullable_field2(x) = x
+end
+
+# julia#18484
+if VERSION < v"0.6.0-dev.848"
+    unsafe_get(x::Nullable) = x.value
+    unsafe_get(x) = x
+    export unsafe_get
+    if VERSION < v"0.4.0-dev+656" # so "nullable.jl" is included
+        isnull(x) = false
+    else
+        Base.isnull(x) = false
+    end
+end
+
 end # module

test/runtests.jl

@@ -1455,3 +1455,57 @@ for A in (Hermitian(randn(5,5) + 10I),
     @test F[:U]'F[:U]  ≈ A[F[:p], F[:p]]
     @test F[:L]*F[:L]' ≈ A[F[:p], F[:p]]
 end
+
+types = [
+    Bool,
+    Float16,
+    Float32,
+    Float64,
+    Int128,
+    Int16,
+    Int32,
+    Int64,
+    Int8,
+    UInt16,
+    UInt32,
+    UInt64,
+    UInt8,
+]
+for T in types
+    # julia#18510, Nullable constructors
+    x = @compat Nullable(one(T), true)
+    @test isnull(x) === false
+    @test isa(x.value, T)
+    @test eltype(x) === T
+
+    x = @compat Nullable{T}(one(T), true)
+    y = @compat Nullable{Any}(one(T), true)
+    @test isnull(x) === false
+    @test isnull(y) === false
+    @test isa(x.value, T)
+    @test eltype(x) === T
+    @test eltype(y) === Any
+
+    x = @compat Nullable{T}(one(T), false)
+    y = @compat Nullable{Any}(one(T), false)
+    @test isnull(x) === true
+    @test isnull(y) === true
+    @test eltype(x) === T
+    @test eltype(y) === Any
+
+    x = @compat Nullable(one(T), false)
+    @test isnull(x) === true
+    @test eltype(x) === T
+
+    x = @compat Nullable{T}()
+    @test isnull(x) === true
+    @test eltype(x) === T
+
+    # julia#18484, generic isnull, unsafe_get
+    a = one(T)
+    x = @compat Nullable(a, true)
+    @test isequal(unsafe_get(x), a)
+
+    x = @compat Nullable{Array{T}}()
+    @test_throws UndefRefError unsafe_get(x)
+end