Remove at-compat for index styles

Was added in #329, now obsolete as no longer required on minimum 
supported Julia version 0.6.

README.md

@@ -63,15 +63,13 @@ Currently, the `@compat` macro supports the following syntaxes:
   to declare abstract and primitive types. [#20418]
   This only works when `@compat` is applied directly on the declaration.
 
-* `@compat Base.IndexStyle(::Type{<:MyArray}) = IndexLinear()` and `@compat Base.IndexStyle(::Type{<:MyArray}) = IndexCartesian()` to define traits for abstract arrays, replacing the former `Base.linearindexing{T<:MyArray}(::Type{T}) = Base.LinearFast()` and `Base.linearindexing{T<:MyArray}(::Type{T}) = Base.LinearSlow()`, respectively.
-
 * `Compat.collect(A)` returns an `Array`, no matter what indices the array `A` has. [#21257]
 
 * `@compat foo(::CartesianRange{N})` to replace the former
   `foo(::CartesianRange{CartesianIndex{N}})` ([#20974]). Note that
   `CartesianRange` now has two type parameters, so using them as
   fields in other `struct`s requires manual intervention.
-  
+
 * Required keyword arguments ([#25830]). For example, `@compat foo(; x, y)` makes `x` and `y` required keyword arguments: when calling `foo`, an error is thrown if `x` or `y` is not explicitly provided.
 
 ## Module Aliases

src/Compat.jl

@@ -250,15 +250,6 @@ include("arraymacros.jl")
 # julia #18839
 import Base.Iterators # TODO deprecate, remove
 
-@static if VERSION < v"0.6.0-dev.2840"
-    export IndexStyle, IndexLinear, IndexCartesian
-    eval(Expr(:typealias, :IndexStyle, :(Base.LinearIndexing)))
-    eval(Expr(:typealias, :IndexLinear, :(Base.LinearFast)))
-    eval(Expr(:typealias, :IndexCartesian, :(Base.LinearSlow)))
-    IndexStyle{T}(::Type{T}) = Base.linearindexing(T)
-    IndexStyle(args...) = Base.linearindexing(args...)
-end
-
 if VERSION < v"0.6.0-dev.1653"
     for (fname, felt) in ((:zeros,:zero), (:ones,:one))
         @eval begin

src/compatmacro.jl

@@ -7,12 +7,6 @@ export @compat
 """Get just the function part of a function declaration."""
 withincurly(ex) = isexpr(ex, :curly) ? ex.args[1] : ex
 
-is_index_style(ex::Expr) = ex == :(Compat.IndexStyle) || ex == :(Base.IndexStyle) ||
-    (ex.head == :(.) && (ex.args[1] == :Compat || ex.args[1] == :Base) &&
-         ex.args[2] == Expr(:quote, :IndexStyle))
-
-is_index_style(arg) = false
-
 istopsymbol(ex, mod, sym) = ex in (sym, Expr(:(.), mod, Expr(:quote, sym)))
 
 if !isdefined(Base, :UndefKeywordError)
@@ -40,18 +34,6 @@ function _compat(ex::Expr)
         # Passthrough
         return ex
     end
-    if VERSION < v"0.6.0-dev.2840"
-        if ex.head == :(=) && isa(ex.args[1], Expr) && ex.args[1].head == :call
-            a = ex.args[1].args[1]
-            if is_index_style(a)
-                ex.args[1].args[1] = :(Base.linearindexing)
-            elseif isa(a, Expr) && a.head == :curly
-                if is_index_style(a.args[1])
-                    ex.args[1].args[1].args[1] = :(Base.linearindexing)
-                end
-            end
-        end
-    end
     if VERSION < v"0.7.0-DEV.880"
         if ex.head == :curly && ex.args[1] == :CartesianRange && length(ex.args) >= 2
             a = ex.args[2]

test/runtests.jl

@@ -434,31 +434,6 @@ end
 @test isbitstype(Primitive20418{Int})
 @test sizeof(Primitive20418{Int}) == 2
 
-module CompatArray
-    using Compat
-    const struct_sym = VERSION < v"0.7.0-DEV.1263" ? :type : :struct
-    eval(Expr(
-        struct_sym, false,
-        Expr(:(<:), :(CartesianArray{T,N}), :(AbstractArray{T,N})),
-        quote
-            parent::Array{T,N}
-        end))
-    eval(Expr(
-        struct_sym, false,
-        Expr(:(<:), :(LinearArray{T,N}), :(AbstractArray{T,N})),
-        quote
-            parent::Array{T,N}
-        end))
-    @compat Base.IndexStyle(::Type{<:LinearArray}) = IndexLinear()
-end
-@test IndexStyle(Array{Float32,2}) === IndexLinear()
-@test IndexStyle(CompatArray.CartesianArray{Float32,2}) === IndexCartesian()
-@test IndexStyle(CompatArray.LinearArray{Float32,2}) === IndexLinear()
-let a = CompatArray.CartesianArray(rand(2,3)), b = CompatArray.LinearArray(rand(2,3))
-    @test IndexStyle(a) === IndexCartesian()
-    @test IndexStyle(b) === IndexLinear()
-end
-
 if VERSION < v"0.6.0-dev.1653"
     for (A,val) in ((zeros(1:5, Float32, 3, 2), 0),
                     (ones(1:5, Float32, 3, 2), 1),