add ismutable to Compat for Julia PR 34652 (#686)

* add  to Compat for Julia PR 34652

Author: ssikdar1

Project.toml

@@ -1,6 +1,6 @@
 name = "Compat"
 uuid = "34da2185-b29b-5c13-b0c7-acf172513d20"
-version = "3.3.1"
+version = "3.4.0"
 
 [deps]
 Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"

README.md

@@ -44,6 +44,8 @@ Please check the list below for the specific syntax you need.
 
 ## Supported features
 
+* `ismutable` return `true` iff value `v` is mutable ([#34652]). (since Compat 3.4.0)
+
 * `uuid5` generates a version 5 universally unique identifier (UUID), as specified by RFC 4122 ([#28761]). (since Compat 3.3.0)
 
 * `dot` now has a 3-argument method `dot(x, A, y)` without storing the intermediate result `A*y` ([#32739]). (since Compat 3.2.0)
@@ -72,6 +74,7 @@ Please check the list below for the specific syntax you need.
 
 * `range` supporting `stop` as positional argument ([#28708]). (since Compat 1.3.0)
 
+
 ## Developer tips
 
 One of the most important rules for `Compat.jl` is to avoid breaking user code
@@ -115,3 +118,4 @@ Note that you should specify the correct minimum version for `Compat` in the
 [#33736]: http://github.com/JuliaLang/julia/pull/33736
 [#32968]: https://github.com/JuliaLang/julia/pull/32968
 [#28761]: https://github.com/JuliaLang/julia/pull/28761
+[#34652]: https://github.com/JuliaLang/julia/pull/34652

src/Compat.jl

@@ -199,6 +199,12 @@ if VERSION < v"1.4.0-DEV.551"
     Base.filter(f, t::Base.Any16) = Tuple(filter(f, collect(t)))
 end
 
+# https://github.com/JuliaLang/julia/pull/34652
+if VERSION < v"1.5.0-DEV.247"
+    export ismutable
+    ismutable(@nospecialize(x)) = (Base.@_pure_meta; typeof(x).mutable)
+end
+
 # https://github.com/JuliaLang/julia/pull/28761
 export uuid5
 if VERSION < v"1.1.0-DEV.326"

test/runtests.jl

@@ -215,6 +215,12 @@ end
     @test filter(x -> x<2, (longtuple..., 1.5)) === (1, 1.5)
 end
 
+# https://github.com/JuliaLang/julia/pull/34652
+@testset "ismutable" begin
+    @test ismutable(1) == false
+    @test ismutable([]) == true
+end             
+
 # https://github.com/JuliaLang/julia/pull/28761
 @testset "uuid5" begin
     u1 = uuid1()