Mark macros_have_sourceloc from #355 for future deprecation

Author: martinholters

README.md

@@ -360,8 +360,6 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * On versions of Julia that do not contain a Base.Threads module, Compat defines a Threads module containing a no-op `@threads` macro.
 
-* The `Expr(:macrocall)` has an extra initial argument `__source__`, which can be tested for with `Compat.macros_have_sourceloc`.
-
 ## New types
 
 * `Compat.AbstractDateTime` is an alias for `Compat.Dates.AbstractDateTime` as of ([#25227]) and `Compat.Dates.TimeType` prior to that.

src/Compat.jl

@@ -11,12 +11,10 @@ module TypeUtils
     export isabstract, parameter_upper_bound, typename
 end # module TypeUtils
 import Base.invokelatest
+const macros_have_sourceloc = true
 
 include("compatmacro.jl")
 
-# https://github.com/JuliaLang/julia/pull/21746
-const macros_have_sourceloc = VERSION >= v"0.7-" && length(:(@test).args) == 2
-
 # 0.7.0-DEV.3155
 @static if !isdefined(Base, :pushfirst!)
     const pushfirst! = unshift!