Add hasfield and hasproperty

README.md

@@ -238,6 +238,9 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `mapslices` with `dims` keyword argument ([#27828]).
 
+* `hasproperty` and `hasfield` ([#28850]).
+  `hasproperty` is defined only for Julia 0.7 or later.
+
 ## Renaming
 
 * `Display` is now `AbstractDisplay` ([#24831]).
@@ -577,3 +580,4 @@ includes this fix. Find the minimum version from there.
 [#28302]: https://github.com/JuliaLang/julia/issues/28302
 [#28303]: https://github.com/JuliaLang/julia/issues/28303
 [#28708]: https://github.com/JuliaLang/julia/issues/28708
+[#28850]: https://github.com/JuliaLang/julia/issues/28850

src/Compat.jl

@@ -1891,6 +1891,17 @@ else
     range(start::Number, stop::Number; kwargs...) = range(start; stop=stop, kwargs...)
 end
 
+# https://github.com/JuliaLang/julia/pull/30496
+if VERSION < v"1.2.0-DEV.272"
+    Base.@pure hasfield(::Type{T}, name::Symbol) where T =
+        Base.fieldindex(T, name, false) > 0
+    export hasfield
+    if VERSION >= v"0.7-"
+        hasproperty(x, s::Symbol) = s in propertynames(x)
+        export hasproperty
+    end
+end
+
 include("deprecated.jl")
 
 end # module Compat

test/runtests.jl

@@ -1532,4 +1532,17 @@ end
 @test Compat.range(0, 5, length = 6) == 0.0:1.0:5.0
 @test Compat.range(0, 10, step = 2) == 0:2:10
 
+mutable struct TLayout
+    x::Int8
+    y::Int16
+    z::Int32
+end
+tlayout = TLayout(5,7,11)
+@test hasfield(TLayout, :y)
+@test !hasfield(TLayout, :a)
+if VERSION >= v"0.7-"
+    @test hasproperty(tlayout, :x)
+    @test !hasproperty(tlayout, :p)
+end
+
 nothing