From 7953e39df15a24693b0441321865aea7dba1f0e6 Mon Sep 17 00:00:00 2001
From: Chris Foster <chris42f@gmail.com>
Date: Mon, 27 Jul 2020 14:03:22 +1000
Subject: [PATCH] Make Base.ifelse a generic function

Allow user code to directly extend `Base.ifelse` rather than needing a
special package for it.
---
 base/boot.jl                            |  4 ++--
 base/compiler/abstractinterpretation.jl |  2 +-
 base/compiler/optimize.jl               |  2 +-
 base/compiler/tfuncs.jl                 |  2 +-
 base/essentials.jl                      | 16 ++++++++++++++++
 base/operators.jl                       | 16 ----------------
 6 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/base/boot.jl b/base/boot.jl
index ee1370bf5dff1..86541c6da827b 100644
--- a/base/boot.jl
+++ b/base/boot.jl
@@ -192,8 +192,8 @@ export
     Expr, QuoteNode, LineNumberNode, GlobalRef,
     # object model functions
     fieldtype, getfield, setfield!, swapfield!, modifyfield!, replacefield!,
-    nfields, throw, tuple, ===, isdefined, eval, ifelse,
-    # sizeof    # not exported, to avoid conflicting with Base.sizeof
+    nfields, throw, tuple, ===, isdefined, eval,
+    # ifelse, sizeof    # not exported, to avoid conflicting with Base
     # type reflection
     <:, typeof, isa, typeassert,
     # method reflection
diff --git a/base/compiler/abstractinterpretation.jl b/base/compiler/abstractinterpretation.jl
index 4af4eb672bb6d..bb91bf15962e8 100644
--- a/base/compiler/abstractinterpretation.jl
+++ b/base/compiler/abstractinterpretation.jl
@@ -1039,7 +1039,7 @@ function abstract_call_builtin(interp::AbstractInterpreter, f::Builtin, fargs::U
         argtypes::Vector{Any}, sv::InferenceState, max_methods::Int)
     @nospecialize f
     la = length(argtypes)
-    if f === ifelse && fargs isa Vector{Any} && la == 4
+    if f === Core.ifelse && fargs isa Vector{Any} && la == 4
         cnd = argtypes[2]
         if isa(cnd, Conditional)
             newcnd = widenconditional(cnd)
diff --git a/base/compiler/optimize.jl b/base/compiler/optimize.jl
index 1898aa8b75778..2594c49815140 100644
--- a/base/compiler/optimize.jl
+++ b/base/compiler/optimize.jl
@@ -139,7 +139,7 @@ const _PURE_BUILTINS = Any[tuple, svec, ===, typeof, nfields]
 const _PURE_OR_ERROR_BUILTINS = [
     fieldtype, apply_type, isa, UnionAll,
     getfield, arrayref, const_arrayref, isdefined, Core.sizeof,
-    Core.kwfunc, ifelse, Core._typevar, (<:)
+    Core.kwfunc, Core.ifelse, Core._typevar, (<:)
 ]
 
 const TOP_TUPLE = GlobalRef(Core, :tuple)
diff --git a/base/compiler/tfuncs.jl b/base/compiler/tfuncs.jl
index a43c9dd9afff1..2db230f425ef9 100644
--- a/base/compiler/tfuncs.jl
+++ b/base/compiler/tfuncs.jl
@@ -230,7 +230,7 @@ function ifelse_tfunc(@nospecialize(cnd), @nospecialize(x), @nospecialize(y))
     end
     return tmerge(x, y)
 end
-add_tfunc(ifelse, 3, 3, ifelse_tfunc, 1)
+add_tfunc(Core.ifelse, 3, 3, ifelse_tfunc, 1)
 
 function egal_tfunc(@nospecialize(x), @nospecialize(y))
     xx = widenconditional(x)
diff --git a/base/essentials.jl b/base/essentials.jl
index 5280252f1946a..cd4b618b5b0b1 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -477,6 +477,22 @@ Stacktrace:
 """
 sizeof(x) = Core.sizeof(x)
 
+"""
+    ifelse(condition::Bool, x, y)
+
+Return `x` if `condition` is `true`, otherwise return `y`. This differs from `?` or `if` in
+that it is an ordinary function, so all the arguments are evaluated first. In some cases,
+using `ifelse` instead of an `if` statement can eliminate the branch in generated code and
+provide higher performance in tight loops.
+
+# Examples
+```jldoctest
+julia> ifelse(1 > 2, 1, 2)
+2
+```
+"""
+ifelse(condition::Bool, x, y) = Core.ifelse(condition, x, y)
+
 # simple Array{Any} operations needed for bootstrap
 @eval setindex!(A::Array{Any}, @nospecialize(x), i::Int) = arrayset($(Expr(:boundscheck)), A, x, i)
 
diff --git a/base/operators.jl b/base/operators.jl
index 74cf3e95145a6..076105c6ac9b9 100644
--- a/base/operators.jl
+++ b/base/operators.jl
@@ -429,22 +429,6 @@ const ≥ = >=
 # which is more idiomatic:
 isless(x::Real, y::Real) = x<y
 
-"""
-    ifelse(condition::Bool, x, y)
-
-Return `x` if `condition` is `true`, otherwise return `y`. This differs from `?` or `if` in
-that it is an ordinary function, so all the arguments are evaluated first. In some cases,
-using `ifelse` instead of an `if` statement can eliminate the branch in generated code and
-provide higher performance in tight loops.
-
-# Examples
-```jldoctest
-julia> ifelse(1 > 2, 1, 2)
-2
-```
-"""
-ifelse
-
 """
     cmp(x,y)