Move gc and gc_enable to their own unexported module

We document that these functions should not generally be used, and yet
they're exported from Base. This moves the two functions into their own
submodule, Base.GCUtils.

Author: ararslan

NEWS.md

@@ -948,6 +948,8 @@ Deprecated or removed
   * `rand(t::Tuple{Vararg{Int}})` is deprecated in favor of `rand(Float64, t)` or `rand(t...)`;
     `rand(::Tuple)` will have another meaning in the future ([#25429], [#25278]).
 
+  * `gc` and `gc_enable` now live in the unexported module `Base.GCUtils` ([#TODO]).
+
 
 Command-line option changes
 ---------------------------

base/deprecated.jl

@@ -2794,6 +2794,9 @@ end
 @deprecate findn(x::AbstractMatrix) (I = findall(!iszero, x); (getindex.(I, 1), getindex.(I, 2)))
 @deprecate findn(x::AbstractArray{T, N}) where {T, N} (I = findall(!iszero, x); ntuple(i -> getindex.(I, i), N))
 
+@deprecate gc Base.GCUtils.gc
+@deprecate gc_enable Base.GCUtils.gc_enable
+
 # issue #9053
 if Sys.iswindows()
 function Filesystem.tempname(uunique::UInt32)

base/exports.jl

@@ -904,8 +904,6 @@ export
 # RTS internals
     finalizer,
     finalize,
-    gc,
-    gc_enable,
     precompile,
 
 # misc

base/gcutils.jl

@@ -38,18 +38,30 @@ Immediately run finalizers registered for object `x`.
 finalize(@nospecialize(o)) = ccall(:jl_finalize_th, Cvoid, (Ptr{Cvoid}, Any,),
                                    Core.getptls(), o)
 
+module GCUtils
+
+export gc, gc_enable
+
 """
     gc()
 
-Perform garbage collection. This should not generally be used.
+Perform garbage collection.
+
+!!! warning
+    This should not generally be used.
 """
 gc(full::Bool=true) = ccall(:jl_gc_collect, Cvoid, (Int32,), full)
 
 """
     gc_enable(on::Bool)
 
 Control whether garbage collection is enabled using a boolean argument (`true` for enabled,
-`false` for disabled). Return previous GC state. Disabling garbage collection should be
-used only with extreme caution, as it can cause memory use to grow without bound.
+`false` for disabled). Return previous GC state.
+
+!!! warning
+    Disabling garbage collection should be used only with extreme caution, as it can cause
+    memory use to grow without bound.
 """
 gc_enable(on::Bool) = ccall(:jl_gc_enable, Int32, (Int32,), on) != 0
+
+end # module GCUtils

doc/src/base/base.md

@@ -331,8 +331,8 @@ Base.@functionloc
 ## Internals
 
 ```@docs
-Base.gc
-Base.gc_enable
+Base.GCUtils.gc
+Base.GCUtils.gc_enable
 Meta.lower
 Meta.@lower
 Meta.parse(::AbstractString, ::Int)

stdlib/FileWatching/test/runtests.jl

@@ -1,6 +1,6 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
-using Test, FileWatching
+using Test, FileWatching, Base.GCUtils
 
 # This script does the following
 # Sets up n unix pipes

stdlib/Mmap/test/runtests.jl

@@ -1,6 +1,6 @@
 # This file is a part of Julia. License is MIT: https://julialang.org/license
 
-using Test, Mmap, Random
+using Test, Mmap, Random, Base.GCUtils
 
 file = tempname()
 write(file, "Hello World\n")

stdlib/SharedArrays/test/runtests.jl

@@ -6,7 +6,7 @@ include(joinpath(Sys.BINDIR, "..", "share", "julia", "test", "testenv.jl"))
 addprocs_with_testenv(4)
 @test nprocs() == 5
 
-@everywhere using Test, SharedArrays
+@everywhere using Test, SharedArrays, Base.GCUtils
 
 id_me = myid()
 id_other = filter(x -> x != id_me, procs())[rand(1:(nprocs()-1))]

stdlib/SparseArrays/test/sparse.jl

@@ -2,6 +2,7 @@
 
 using Base.LinAlg: mul!, ldiv!, rdiv!
 using Base.Printf: @printf
+using Base.GCUtils
 using Random
 
 @testset "issparse" begin

stdlib/SuiteSparse/test/cholmod.jl

@@ -3,6 +3,7 @@
 using SuiteSparse.CHOLMOD
 using DelimitedFiles
 using Test
+using Base.GCUtils
 
 # CHOLMOD tests
 srand(123)