fix dict x == x to return missing if x contains it

closes #34744

use `isequal` to compare keys in `ImmutableDict`

base/abstractdict.jl

@@ -17,9 +17,9 @@ const secret_table_token = :__c782dbf1cf4d6a2e5e3865d7e95634f2e09b5902__
 haskey(d::AbstractDict, k) = in(k, keys(d))
 
 function in(p::Pair, a::AbstractDict, valcmp=(==))
-    v = get(a,p[1],secret_table_token)
+    v = get(a, p.first, secret_table_token)
     if v !== secret_table_token
-        return valcmp(v, p[2])
+        return valcmp(v, p.second)
     end
     return false
 end
@@ -474,14 +474,16 @@ function isequal(l::AbstractDict, r::AbstractDict)
 end
 
 function ==(l::AbstractDict, r::AbstractDict)
-    l === r && return true
+    if l === r
+        return any(ismissing, values(l)) ? missing : true
+    end
     if isa(l,IdDict) != isa(r,IdDict)
         return false
     end
     length(l) != length(r) && return false
     anymissing = false
     for pair in l
-        isin = in(pair, r, ==)
+        isin = in(pair, r)
         if ismissing(isin)
             anymissing = true
         elseif !isin

base/dict.jl

@@ -746,7 +746,7 @@ ImmutableDict(KV::Pair, rest::Pair...) = ImmutableDict(ImmutableDict(rest...), K
 function in(key_value::Pair, dict::ImmutableDict, valcmp=(==))
     key, value = key_value
     while isdefined(dict, :parent)
-        if dict.key == key
+        if isequal(dict.key, key)
             valcmp(value, dict.value) && return true
         end
         dict = dict.parent
@@ -756,22 +756,22 @@ end
 
 function haskey(dict::ImmutableDict, key)
     while isdefined(dict, :parent)
-        dict.key == key && return true
+        isequal(dict.key, key) && return true
         dict = dict.parent
     end
     return false
 end
 
 function getindex(dict::ImmutableDict, key)
     while isdefined(dict, :parent)
-        dict.key == key && return dict.value
+        isequal(dict.key, key) && return dict.value
         dict = dict.parent
     end
     throw(KeyError(key))
 end
 function get(dict::ImmutableDict, key, default)
     while isdefined(dict, :parent)
-        dict.key == key && return dict.value
+        isequal(dict.key, key) && return dict.value
         dict = dict.parent
     end
     return default

test/dict.jl

@@ -277,6 +277,8 @@ end
 
     @test ismissing(Dict(1=>missing) == Dict(1=>missing))
     @test isequal(Dict(1=>missing), Dict(1=>missing))
+    d = Dict(1=>missing)
+    @test ismissing(d == d)
 
     @test Dict(missing=>1) == Dict(missing=>1)
     @test isequal(Dict(missing=>1), Dict(missing=>1))
@@ -716,6 +718,8 @@ import Base.ImmutableDict
     d5 = ImmutableDict(v...)
     @test d5 == d2
     @test collect(d5) == v
+
+    @test !haskey(ImmutableDict(-0.0=>1), 0.0)
 end
 
 @testset "filtering" begin