Deprecate is_<os> functions in favor of Sys.is<os>

This makes them consistent with the vast majority of Base predicates,
which simply prefix with `is` rather than `is_`. It also moves to
requiring the `Sys.` prefix, which helps explain the intent behind the
function names.

Author: ararslan

NEWS.md

@@ -160,6 +160,11 @@ Deprecated or removed
   * `InexactError` now takes arguments: `InexactError(func::Symbol,
     type, -3)` now prints as `ERROR: InexactError: func(type, -3)`. ([#20005])
 
+  * The operating system identification functions: `is_linux`, `is_bsd`, `is_apple`, `is_unix`,
+    and `is_windows`, have been deprecated in favor of `Sys.islinux`, `Sys.isbsd`, `Sys.isapple`,
+    `Sys.isunix`, and `Sys.iswindows`, respectively ([#22182]).
+
+
 Julia v0.6.0 Release Notes
 ==========================
 
@@ -954,6 +959,7 @@ Command-line option changes
 [#22038]: https://github.com/JuliaLang/julia/issues/22038
 [#22062]: https://github.com/JuliaLang/julia/issues/22062
 [#22064]: https://github.com/JuliaLang/julia/issues/22064
+[#22182]: https://github.com/JuliaLang/julia/issues/22182
 [#22187]: https://github.com/JuliaLang/julia/issues/22187
 [#22188]: https://github.com/JuliaLang/julia/issues/22188
 [#22224]: https://github.com/JuliaLang/julia/issues/22224

base/c.jl

@@ -18,7 +18,8 @@ Equivalent to the native `char` c-type.
 """
 Cchar
 
-if is_windows()
+# The ccall here is equivalent to Sys.iswindows(), but that's not defined yet
+@static if ccall(:jl_get_UNAME, Any, ()) === :NT
     const Clong = Int32
     const Culong = UInt32
     const Cwchar_t = UInt16
@@ -49,7 +50,7 @@ Equivalent to the native `wchar_t` c-type ([`Int32`](@ref)).
 """
 Cwchar_t
 
-if !is_windows()
+@static if ccall(:jl_get_UNAME, Any, ()) !== :NT
     const sizeof_mode_t = ccall(:jl_sizeof_mode_t, Cint, ())
     if sizeof_mode_t == 2
         const Cmode_t = Int16
@@ -118,7 +119,7 @@ end
 # symbols are guaranteed not to contain embedded NUL
 convert(::Type{Cstring}, s::Symbol) = Cstring(unsafe_convert(Ptr{Cchar}, s))
 
-if is_windows()
+@static if ccall(:jl_get_UNAME, Any, ()) === :NT
 """
     Base.cwstring(s)
 

base/client.jl

@@ -102,15 +102,15 @@ function repl_cmd(cmd, out)
                 end
                 cd(ENV["OLDPWD"])
             else
-                cd(@static is_windows() ? dir : readchomp(`$shell -c "echo $(shell_escape(dir))"`))
+                cd(@static Sys.iswindows() ? dir : readchomp(`$shell -c "echo $(shell_escape(dir))"`))
             end
         else
             cd()
         end
         ENV["OLDPWD"] = new_oldpwd
         println(out, pwd())
     else
-        run(ignorestatus(@static is_windows() ? cmd : (isa(STDIN, TTY) ? `$shell -i -c "$(shell_wrap_true(shell_name, cmd))"` : `$shell -c "$(shell_wrap_true(shell_name, cmd))"`)))
+        run(ignorestatus(@static Sys.iswindows() ? cmd : (isa(STDIN, TTY) ? `$shell -i -c "$(shell_wrap_true(shell_name, cmd))"` : `$shell -c "$(shell_wrap_true(shell_name, cmd))"`)))
     end
     nothing
 end
@@ -390,7 +390,7 @@ function _start()
                 global is_interactive |= !isa(STDIN, Union{File, IOStream})
                 color_set || (global have_color = false)
             else
-                term = Terminals.TTYTerminal(get(ENV, "TERM", @static is_windows() ? "" : "dumb"), STDIN, STDOUT, STDERR)
+                term = Terminals.TTYTerminal(get(ENV, "TERM", @static Sys.iswindows() ? "" : "dumb"), STDIN, STDOUT, STDERR)
                 global is_interactive = true
                 color_set || (global have_color = Terminals.hascolor(term))
                 quiet || REPL.banner(term,term)

base/dSFMT.jl

@@ -163,7 +163,7 @@ end
 
 ## Windows entropy
 
-if is_windows()
+if Sys.iswindows()
     function win32_SystemFunction036!(a::Array)
         ccall((:SystemFunction036, :Advapi32), stdcall, UInt8, (Ptr{Void}, UInt32), a, sizeof(a))
     end

base/datafmt.jl

@@ -120,7 +120,7 @@ readdlm_auto(input::IO, dlm::Char, T::Type, eol::Char, auto::Bool; opts...) =
     readdlm_string(readstring(input), dlm, T, eol, auto, val_opts(opts))
 function readdlm_auto(input::AbstractString, dlm::Char, T::Type, eol::Char, auto::Bool; opts...)
     optsd = val_opts(opts)
-    use_mmap = get(optsd, :use_mmap, is_windows() ? false : true)
+    use_mmap = get(optsd, :use_mmap, Sys.iswindows() ? false : true)
     fsz = filesize(input)
     if use_mmap && fsz > 0 && fsz < typemax(Int)
         a = open(input, "r") do f

base/deprecated.jl

@@ -1570,6 +1570,13 @@ end
 # nfields(::Type) deprecation in builtins.c: update nfields tfunc in inference.jl when it is removed.
 # also replace `_nfields` with `nfields` in summarysize.c when this is removed.
 
+# PR #22182
+@deprecate is_apple   Sys.isapple
+@deprecate is_bsd     Sys.isbsd
+@deprecate is_linux   Sys.islinux
+@deprecate is_unix    Sys.isunix
+@deprecate is_windows Sys.iswindows
+
 # END 0.7 deprecations
 
 # BEGIN 1.0 deprecations

base/distributed/cluster.jl

@@ -975,7 +975,7 @@ end
 function disable_nagle(sock)
     # disable nagle on all OSes
     ccall(:uv_tcp_nodelay, Cint, (Ptr{Void}, Cint), sock.handle, 1)
-    @static if is_linux()
+    @static if Sys.islinux()
         # tcp_quickack is a linux only option
         if ccall(:jl_tcp_quickack, Cint, (Ptr{Void}, Cint), sock.handle, 1) < 0
             warn_once("Networking unoptimized ( Error enabling TCP_QUICKACK : ", Libc.strerror(Libc.errno()), " )")

base/distributed/managers.jl

@@ -460,7 +460,7 @@ function socket_reuse_port()
         s = TCPSocket(delay = false)
 
         # Some systems (e.g. Linux) require the port to be bound before setting REUSEPORT
-        bind_early = is_linux()
+        bind_early = Sys.islinux()
 
         bind_early && bind_client_port(s)
         rc = ccall(:jl_tcp_reuseport, Int32, (Ptr{Void},), s.handle)

base/env.jl

@@ -1,6 +1,6 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
-if is_windows()
+if Sys.iswindows()
     const ERROR_ENVVAR_NOT_FOUND = UInt32(203)
 
     _getenvlen(var::Vector{UInt16}) = ccall(:GetEnvironmentVariableW,stdcall,UInt32,(Ptr{UInt16},Ptr{UInt16},UInt32),var,C_NULL,0)
@@ -84,7 +84,7 @@ delete!(::EnvHash, k::AbstractString) = (_unsetenv(k); ENV)
 setindex!(::EnvHash, v, k::AbstractString) = _setenv(k,string(v))
 push!(::EnvHash, k::AbstractString, v) = setindex!(ENV, v, k)
 
-if is_windows()
+if Sys.iswindows()
     start(hash::EnvHash) = (pos = ccall(:GetEnvironmentStringsW,stdcall,Ptr{UInt16},()); (pos,pos))
     function done(hash::EnvHash, block::Tuple{Ptr{UInt16},Ptr{UInt16}})
         if unsafe_load(block[1]) == 0

base/event.jl

@@ -247,7 +247,7 @@ function wait()
     # unreachable
 end
 
-if is_windows()
+if Sys.iswindows()
     pause() = ccall(:Sleep, stdcall, Void, (UInt32,), 0xffffffff)
 else
     pause() = ccall(:pause, Void, ())