deprecate merge(::Callable ..) in favor of mergewith (#59775)

after #34296 this method is
redundant, and it's also undocumented. according to
#43491 (comment),
`Callable` should not be used anymore, so it might make sense to remove
from `Base` where feasible.

Author: adienes

Compiler/test/inference.jl

@@ -3509,11 +3509,11 @@ end
 struct MixedKeyDict{T<:Tuple} #<: AbstractDict{Any,Any}
     dicts::T
 end
-Base.merge(f::Function, d::MixedKeyDict, others::MixedKeyDict...) = _merge(f, (), d.dicts, (d->d.dicts).(others)...)
-Base.merge(f, d::MixedKeyDict, others::MixedKeyDict...) = _merge(f, (), d.dicts, (d->d.dicts).(others)...)
+Base.mergewith(f::Function, d::MixedKeyDict, others::MixedKeyDict...) = _merge(f, (), d.dicts, (d->d.dicts).(others)...)
+Base.mergewith(f, d::MixedKeyDict, others::MixedKeyDict...) = _merge(f, (), d.dicts, (d->d.dicts).(others)...)
 function _merge(f, res, d, others...)
     ofsametype, remaining = _alloftype(Base.heads(d), ((),), others...)
-    return _merge(f, (res..., merge(f, ofsametype...)), Base.tail(d), remaining...)
+    return _merge(f, (res..., mergewith(f, ofsametype...)), Base.tail(d), remaining...)
 end
 _merge(f, res, ::Tuple{}, others...) = _merge(f, res, others...)
 _merge(f, res, d) = MixedKeyDict((res..., d...))
@@ -3537,9 +3537,9 @@ _alloftype(ofdesiredtype, accumulated) = ofdesiredtype, Base.front(accumulated)
 let
     d = MixedKeyDict((Dict(1 => 3), Dict(4. => 2)))
     e = MixedKeyDict((Dict(1 => 7), Dict(5. => 9)))
-    @test merge(+, d, e).dicts == (Dict(1 => 10), Dict(4.0 => 2, 5.0 => 9))
+    @test mergewith(+, d, e).dicts == (Dict(1 => 10), Dict(4.0 => 2, 5.0 => 9))
     f = MixedKeyDict((Dict(2 => 7), Dict(5. => 11)))
-    @test merge(+, d, e, f).dicts == (Dict(1 => 10, 2 => 7), Dict(4.0 => 2, 5.0 => 20))
+    @test mergewith(+, d, e, f).dicts == (Dict(1 => 10, 2 => 7), Dict(4.0 => 2, 5.0 => 20))
 end
 
 # Issue #31974

NEWS.md

@@ -123,4 +123,9 @@ External dependencies
 Tooling Improvements
 --------------------
 
+Deprecated or removed
+---------------------
+
+* The method `merge(combine::Callable, d::AbstractDict...)` is now deprecated to favor `mergewith` instead ([#59775]).
+
 <!--- generated by NEWS-update.jl: -->

base/deprecated.jl

@@ -566,3 +566,9 @@ end
 to_power_type(x) = oftype(x*x, x)
 
 # END 1.12 deprecations
+
+# BEGIN 1.13 deprecations
+
+@deprecate merge(combine::Callable, d::AbstractDict, others::AbstractDict...) mergewith(combine, d, others...)
+
+# end 1.13 deprecations

test/dict.jl

@@ -1289,8 +1289,6 @@ struct NonFunctionCallable end
     @test @inferred mergewith(NonFunctionCallable(), d1, d2) == Dict("A" => 1, "B" => 5, "C" => 4)
     @test foldl(mergewith(+), [d1, d2]; init=Dict{Union{},Union{}}()) ==
         Dict("A" => 1, "B" => 5, "C" => 4)
-    # backward compatibility
-    @test @inferred merge(+, d1, d2) == Dict("A" => 1, "B" => 5, "C" => 4)
 end
 
 @testset "Dict merge!" begin