Compat for at-vectorize_(1|2)arg deprecation

Provide `Compat.@vectorize_1arg` and `Compat.@vectorize_2arg` as an upgrade
path for packages.

README.md

@@ -221,6 +221,12 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `Compat.@blasfunc` makes functionality of `Base.LinAlg.BLAS.@blasfunc` available on older Julia versions
 
+* `@vectorize_1arg` and `@vectorize_2arg` are deprecated on Julia 0.6 in favor
+  of the broadcast syntax. `Compat.@vectorize_1arg` and `Compat.@vectorize_2arg`
+  are provided so that packages can still provide the deprecated definitions
+  without causing a depwarn in the package itself before all the users
+  are upgraded.
+
 ## Other changes
 
 * `Dict(ks, vs)` is now `Dict(zip(ks, vs))` [#8521](https://github.com/JuliaLang/julia/pull/8521)

src/Compat.jl

@@ -1463,4 +1463,35 @@ if VERSION < v"0.6.0-dev.374"
     end
 end
 
+# PR #17302
+# Provide a non-deprecated version of `@vectorize_(1|2)arg` macro which defines
+# deprecated version of the function so that the depwarns can be fixed without
+# breaking users.
+if VERSION >= v"0.6.0-dev.481"
+    # Copied from Base.
+    macro vectorize_1arg(S, f)
+        S = esc(S)
+        f = esc(f)
+        T = esc(:T)
+        x = esc(:x)
+        AbsArr = esc(:AbstractArray)
+        :(@deprecate $f{$T<:$S}($x::$AbsArr{$T}) $f.($x))
+    end
+
+    macro vectorize_2arg(S, f)
+        S = esc(S)
+        f = esc(f)
+        T1 = esc(:T1)
+        T2 = esc(:T2)
+        x = esc(:x)
+        y = esc(:y)
+        AbsArr = esc(:AbstractArray)
+        quote
+            @deprecate $f{$T1<:$S}($x::$S, $y::$AbsArr{$T1}) $f.($x,$y)
+            @deprecate $f{$T1<:$S}($x::$AbsArr{$T1}, $y::$S) $f.($x,$y)
+            @deprecate $f{$T1<:$S,$T2<:$S}($x::$AbsArr{$T1}, $y::$AbsArr{$T2}) $f.($x,$y)
+        end
+    end
+end
+
 end # module

test/runtests.jl

@@ -1381,3 +1381,19 @@ let filename = tempname()
     @test contains(ret, "WARNING: hello")
     rm(filename)
 end
+
+# PR #17302
+f17302(a::Number) = a
+f17302(a::Number, b::Number) = a + b
+Compat.@vectorize_1arg Real f17302
+Compat.@vectorize_2arg Real f17302
+@test_throws MethodError f17302([1im])
+@test_throws MethodError f17302([1im], [1im])
+mktemp() do fname, f
+    redirect_stderr(f) do
+        @test f17302([1.0]) == [1.0]
+        @test f17302(1.0, [1]) == [2.0]
+        @test f17302([1.0], 1) == [2.0]
+        @test f17302([1.0], [1]) == [2.0]
+    end
+end