Fix duplicate error when using generator in Dict (JuliaLang#53151)

Fixes: JuliaLang#33147 Replaces/Closes: JuliaLang#40445 The difference here, compared to past implementations, is that we use the zero-cost `isiterable` check on every intermediate step, instead of wrapping the call in a try/catch and then trying to re-approximate the `isiterable` afterwards. Some samples: ```julia julia> Dict(i for i in 1:3) ERROR: ArgumentError: AbstractDict(kv): kv needs to be an iterator of 2-tuples or pairs Stacktrace: [1] _throw_dict_kv_error() @ Base ./dict.jl:118 [2] grow_to! @ ./dict.jl:132 [inlined] [3] dict_with_eltype @ ./abstractdict.jl:592 [inlined] [4] Dict(kv::Base.Generator{UnitRange{Int64}, typeof(identity)}) @ Base ./dict.jl:120 [5] top-level scope @ REPL[1]:1 julia> Dict(i => error("$i") for i in 1:3) ERROR: 1 Stacktrace: [1] error(s::String) @ Base ./error.jl:35 [2] (::var"mmtk#3#4")(i::Int64) @ Main ./none:0 [3] iterate @ ./generator.jl:48 [inlined] [4] grow_to! @ ./dict.jl:124 [inlined] [5] dict_with_eltype @ ./abstractdict.jl:592 [inlined] [6] Dict(kv::Base.Generator{UnitRange{Int64}, var"mmtk#3#4"}) @ Base ./dict.jl:120 [7] top-level scope @ REPL[2]:1 ``` The other unrelated change here is that `dest = empty(dest, typeof(k), typeof(v))` is made conditional, so we do not unconditionally construct an empty Dict in order to discard it and allocate an exact duplicate of it, but only do so if inference wasn't precise originally. Co-authored-by: Curtis Vogt <curtis.vogt@gmail.com>
qinsoon · Feb 10, 2024 · 5547305 · 5547305
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Showing 5 changed files with 76 additions and 62 deletions.
diff --git a/base/abstractdict.jl b/base/abstractdict.jl
@@ -579,6 +579,55 @@ _tablesz(x::T) where T <: Integer = x < 16 ? T(16) : one(T)<<(top_set_bit(x-one(
 
 TP{K,V} = Union{Type{Tuple{K,V}},Type{Pair{K,V}}}
 
+# This error is thrown if `grow_to!` cannot validate the contents of the iterator argument to it, which it does by testing the iteration protocol (isiterable) on it each time it is about to start iteration on it
+_throw_dict_kv_error() = throw(ArgumentError("AbstractDict(kv): kv needs to be an iterator of 2-tuples or pairs"))
+
+function grow_to!(dest::AbstractDict, itr)
+    applicable(iterate, itr) || _throw_dict_kv_error()
+    y = iterate(itr)
+    y === nothing && return dest
+    kv, st = y
+    applicable(iterate, kv) || _throw_dict_kv_error()
+    k = iterate(kv)
+    k === nothing && _throw_dict_kv_error()
+    k, kvst = k
+    v = iterate(kv, kvst)
+    v === nothing && _throw_dict_kv_error()
+    v, kvst = v
+    iterate(kv, kvst) === nothing || _throw_dict_kv_error()
+    if !(dest isa AbstractDict{typeof(k), typeof(v)})
+        dest = empty(dest, typeof(k), typeof(v))
+    end
+    dest[k] = v
+    return grow_to!(dest, itr, st)
+end
+
+function grow_to!(dest::AbstractDict{K,V}, itr, st) where {K, V}
+    y = iterate(itr, st)
+    while y !== nothing
+        kv, st = y
+        applicable(iterate, kv) || _throw_dict_kv_error()
+        kst = iterate(kv)
+        kst === nothing && _throw_dict_kv_error()
+        k, kvst = kst
+        vst = iterate(kv, kvst)
+        vst === nothing && _throw_dict_kv_error()
+        v, kvst = vst
+        iterate(kv, kvst) === nothing || _throw_dict_kv_error()
+        if isa(k, K) && isa(v, V)
+            dest[k] = v
+        else
+            new = empty(dest, promote_typejoin(K, typeof(k)), promote_typejoin(V, typeof(v)))
+            merge!(new, dest)
+            new[k] = v
+            return grow_to!(new, itr, st)
+        end
+        y = iterate(itr, st)
+    end
+    return dest
+end
+
+
 dict_with_eltype(DT_apply, kv, ::TP{K,V}) where {K,V} = DT_apply(K, V)(kv)
 dict_with_eltype(DT_apply, kv::Generator, ::TP{K,V}) where {K,V} = DT_apply(K, V)(kv)
 dict_with_eltype(DT_apply, ::Type{Pair{K,V}}) where {K,V} = DT_apply(K, V)()

diff --git a/base/dict.jl b/base/dict.jl
@@ -114,45 +114,7 @@ const AnyDict = Dict{Any,Any}
 Dict(ps::Pair{K,V}...) where {K,V} = Dict{K,V}(ps)
 Dict(ps::Pair...)                  = Dict(ps)
 
-function Dict(kv)
-    try
-        dict_with_eltype((K, V) -> Dict{K, V}, kv, eltype(kv))
-    catch
-        if !isiterable(typeof(kv)) || !all(x->isa(x,Union{Tuple,Pair}),kv)
-            throw(ArgumentError("Dict(kv): kv needs to be an iterator of tuples or pairs"))
-        else
-            rethrow()
-        end
-    end
-end
-
-function grow_to!(dest::AbstractDict{K, V}, itr) where V where K
-    y = iterate(itr)
-    y === nothing && return dest
-    ((k,v), st) = y
-    dest2 = empty(dest, typeof(k), typeof(v))
-    dest2[k] = v
-    grow_to!(dest2, itr, st)
-end
-
-# this is a special case due to (1) allowing both Pairs and Tuples as elements,
-# and (2) Pair being invariant. a bit annoying.
-function grow_to!(dest::AbstractDict{K,V}, itr, st) where V where K
-    y = iterate(itr, st)
-    while y !== nothing
-        (k,v), st = y
-        if isa(k,K) && isa(v,V)
-            dest[k] = v
-        else
-            new = empty(dest, promote_typejoin(K,typeof(k)), promote_typejoin(V,typeof(v)))
-            merge!(new, dest)
-            new[k] = v
-            return grow_to!(new, itr, st)
-        end
-        y = iterate(itr, st)
-    end
-    return dest
-end
+Dict(kv) = dict_with_eltype((K, V) -> Dict{K, V}, kv, eltype(kv))
 
 empty(a::AbstractDict, ::Type{K}, ::Type{V}) where {K, V} = Dict{K, V}()
 

diff --git a/base/iddict.jl b/base/iddict.jl
@@ -53,18 +53,7 @@ IdDict(ps::Pair{K}...)             where {K}   = IdDict{K,Any}(ps)
 IdDict(ps::(Pair{K,V} where K)...) where {V}   = IdDict{Any,V}(ps)
 IdDict(ps::Pair...)                            = IdDict{Any,Any}(ps)
 
-function IdDict(kv)
-    try
-        dict_with_eltype((K, V) -> IdDict{K, V}, kv, eltype(kv))
-    catch
-        if !applicable(iterate, kv) || !all(x->isa(x,Union{Tuple,Pair}),kv)
-            throw(ArgumentError(
-                "IdDict(kv): kv needs to be an iterator of tuples or pairs"))
-        else
-            rethrow()
-        end
-    end
-end
+IdDict(kv) = dict_with_eltype((K, V) -> IdDict{K, V}, kv, eltype(kv))
 
 empty(d::IdDict, ::Type{K}, ::Type{V}) where {K, V} = IdDict{K,V}()
 

diff --git a/base/weakkeydict.jl b/base/weakkeydict.jl
@@ -54,17 +54,7 @@ WeakKeyDict(ps::Pair{K}...)             where {K}   = WeakKeyDict{K,Any}(ps)
 WeakKeyDict(ps::(Pair{K,V} where K)...) where {V}   = WeakKeyDict{Any,V}(ps)
 WeakKeyDict(ps::Pair...)                            = WeakKeyDict{Any,Any}(ps)
 
-function WeakKeyDict(kv)
-    try
-        Base.dict_with_eltype((K, V) -> WeakKeyDict{K, V}, kv, eltype(kv))
-    catch
-        if !isiterable(typeof(kv)) || !all(x->isa(x,Union{Tuple,Pair}),kv)
-            throw(ArgumentError("WeakKeyDict(kv): kv needs to be an iterator of tuples or pairs"))
-        else
-            rethrow()
-        end
-    end
-end
+WeakKeyDict(kv) = Base.dict_with_eltype((K, V) -> WeakKeyDict{K, V}, kv, eltype(kv))
 
 function _cleanup_locked(h::WeakKeyDict)
     if h.dirty

diff --git a/test/dict.jl b/test/dict.jl
@@ -162,6 +162,30 @@ end
 
     # issue #39117
     @test Dict(t[1]=>t[2] for t in zip((1,"2"), (2,"2"))) == Dict{Any,Any}(1=>2, "2"=>"2")
+
+    @testset "issue #33147" begin
+        expected = try; Base._throw_dict_kv_error(); catch e; e; end
+        @test_throws expected Dict(i for i in 1:2)
+        @test_throws expected Dict(nothing for i in 1:2)
+        @test_throws expected Dict(() for i in 1:2)
+        @test_throws expected Dict((i, i, i) for i in 1:2)
+        @test_throws expected Dict(nothing)
+        @test_throws expected Dict((1,))
+        @test_throws expected Dict(1:2)
+        @test_throws expected Dict(((),))
+        @test_throws expected IdDict(((),))
+        @test_throws expected WeakKeyDict(((),))
+        @test_throws expected IdDict(nothing)
+        @test_throws expected WeakKeyDict(nothing)
+        @test Dict(1:0) isa Dict
+        @test Dict(()) isa Dict
+        try
+            Dict(i => error("$i") for i in 1:3)
+        catch ex
+            @test ex isa ErrorException
+            @test length(Base.current_exceptions()) == 1
+        end
+    end
 end
 
 @testset "empty tuple ctor" begin