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inference: limit single-level nested Type signature
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Previously `type_more_complex` returns `false` for `Type{Type{...}}`
compared against `Type{...}`. Per comment there, this should return `true`,
but the code was ordered incorrect (it was also missing support for
Vararg, after the recent changes).

Fixes #40336

Co-authored-by: Shuhei Kadowaki <[email protected]>
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@vtjnash @aviatesk
vtjnash and aviatesk committed Apr 6, 2021
1 parent bda6b94 commit 03b4aac
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Showing 2 changed files with 53 additions and 26 deletions.
44 changes: 22 additions & 22 deletions base/compiler/typelimits.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -128,7 +128,15 @@ function _limit_type_size(@nospecialize(t), @nospecialize(c), sources::SimpleVec
end
return Vararg{VaT}
elseif isa(t, DataType)
if isa(c, DataType)
if isa(c, Core.TypeofVararg)
# Tuple{Vararg{T}} --> Tuple{T} is OK
return _limit_type_size(t, c.T, sources, depth, 0)
elseif isType(t) # allow taking typeof as Type{...}, but ensure it doesn't start nesting
tt = unwrap_unionall(t.parameters[1])
(!isa(tt, DataType) || isType(tt)) && (depth += 1)
is_derived_type_from_any(tt, sources, depth) && return t
return Type
elseif isa(c, DataType)
tP = t.parameters
cP = c.parameters
if t.name === c.name && !isempty(cP)
Expand Down Expand Up @@ -158,15 +166,6 @@ function _limit_type_size(@nospecialize(t), @nospecialize(c), sources::SimpleVec
return Tuple{Q...}
end
end
elseif isa(c, Core.TypeofVararg)
# Tuple{Vararg{T}} --> Tuple{T} is OK
return _limit_type_size(t, c.T, sources, depth, 0)
end
if isType(t) # allow taking typeof as Type{...}, but ensure it doesn't start nesting
tt = unwrap_unionall(t.parameters[1])
if isa(tt, DataType) && !isType(tt)
is_derived_type_from_any(tt, sources, depth) && return t
end
end
if allowed_tuplelen < 1 && t.name === Tuple.name
return Any
Expand Down Expand Up @@ -226,17 +225,27 @@ function type_more_complex(@nospecialize(t), @nospecialize(c), sources::SimpleVe
return t !== 1 && !(0 <= t < c) # alternatively, could use !(abs(t) <= abs(c) || abs(t) < n) for some n
end
# base case for data types
if isa(t, DataType)
if isa(t, Core.TypeofVararg)
if isa(c, Core.TypeofVararg)
return type_more_complex(unwrapva(t), unwrapva(c), sources, depth + 1, tupledepth, 0)
end
elseif isa(t, DataType)
tP = t.parameters
if isa(c, DataType) && t.name === c.name
if isa(c, Core.TypeofVararg)
return type_more_complex(t, unwrapva(c), sources, depth, tupledepth, 0)
elseif isType(t) # allow taking typeof any source type anywhere as Type{...}, as long as it isn't nesting Type{Type{...}}
tt = unwrap_unionall(t.parameters[1])
(!isa(tt, DataType) || isType(tt)) && (depth += 1)
return !is_derived_type_from_any(tt, sources, depth)
elseif isa(c, DataType) && t.name === c.name
cP = c.parameters
length(cP) < length(tP) && return true
length(cP) > length(tP) && !isvarargtype(tP[end]) && depth == 1 && return false
ntail = length(cP) - length(tP) # assume parameters were dropped from the tuple head
# allow creating variation within a nested tuple, but only so deep
if t.name === Tuple.name && tupledepth > 0
tupledepth -= 1
elseif !isvarargtype(t)
else
tupledepth = 0
end
isgenerator = (t.name.name === :Generator && t.name.module === _topmod(t.name.module))
Expand All @@ -258,15 +267,6 @@ function type_more_complex(@nospecialize(t), @nospecialize(c), sources::SimpleVe
type_more_complex(tPi, cPi, sources, depth + 1, tupledepth, 0) && return true
end
return false
elseif isvarargtype(c)
return type_more_complex(t, unwrapva(c), sources, depth, tupledepth, 0)
end
if isType(t) # allow taking typeof any source type anywhere as Type{...}, as long as it isn't nesting Type{Type{...}}
tt = unwrap_unionall(t.parameters[1])
if isa(tt, DataType) && !isType(tt)
is_derived_type_from_any(tt, sources, depth) || return true
return false
end
end
end
return true
Expand Down
35 changes: 31 additions & 4 deletions test/compiler/inference.jl
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,13 @@ let t = Tuple{Ref{T},T,T} where T, c = Tuple{Ref, T, T} where T # #36407
@test t <: Core.Compiler.limit_type_size(t, c, Union{}, 1, 100)
end

let # 40336
t = Type{Type{Int}}
c = Type{Int}
r = Core.Compiler.limit_type_size(t, c, c, 100, 100)
@test t !== r && t <: r
end

@test Core.Compiler.unionlen(Union{}) == 1
@test Core.Compiler.unionlen(Int8) == 1
@test Core.Compiler.unionlen(Union{Int8, Int16}) == 2
Expand Down Expand Up @@ -3171,8 +3178,6 @@ end
end

@testset "constant prop' for union split signature" begin
anonymous_module() = Core.eval(@__MODULE__, :(module $(gensym()) end))::Module

# indexing into tuples really relies on constant prop', and we will get looser result
# (`Union{Int,String,Char}`) if constant prop' doesn't happen for splitunion signatures
tt = (Union{Tuple{Int,String},Tuple{Int,Char}},)
Expand All @@ -3191,7 +3196,7 @@ end
b
end == Any[Union{String,Char}]

@test (@eval anonymous_module() begin
@test (@eval Module() begin
struct F32
val::Float32
_v::Int
Expand All @@ -3205,7 +3210,7 @@ end
end
end) == Any[Union{Float32,Float64}]

@test (@eval anonymous_module() begin
@test (@eval Module() begin
struct F32
val::Float32
_v
Expand Down Expand Up @@ -3243,3 +3248,25 @@ end
Some(0x2)
end
end == [Union{Some{Float64}, Some{Int}, Some{UInt8}}]

# https://github.com/JuliaLang/julia/issues/40336
@testset "make sure a call with signatures with recursively nested Types terminates" begin
@test @eval Module() begin
f(@nospecialize(t)) = f(Type{t})

code_typed() do
f(Int)
end
true
end

@test @eval Module() begin
f(@nospecialize(t)) = tdepth(t) == 10 ? t : f(Type{t})
tdepth(@nospecialize(t)) = isempty(t.parameters) ? 1 : 1+tdepth(t.parameters[1])

code_typed() do
f(Int)
end
true
end
end

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