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typeintersect bug with NTuple #32392

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vtjnash opened this issue Jun 21, 2019 · 3 comments · Fixed by #49111
Closed

typeintersect bug with NTuple #32392

vtjnash opened this issue Jun 21, 2019 · 3 comments · Fixed by #49111
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bug Indicates an unexpected problem or unintended behavior types and dispatch Types, subtyping and method dispatch

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@vtjnash
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vtjnash commented Jun 21, 2019 

julia> typeintersect((Tuple{Vararg{Union{},A}} where A), Tuple{Int64, Vararg{Int64, N} where N}) !== Union{}
false

This is bad since the intersection is non-empty when A is later given:

julia> typeintersect((Tuple{Vararg{Union{},3}} where A), Tuple{Int64, Vararg{Int64, N} where N}) !== Union{}
true
@vtjnash vtjnash added the types and dispatch Types, subtyping and method dispatch label Jun 21, 2019
@Keno
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Keno commented Jun 23, 2019

I thought we at some point had Tuple{Union{},Union{},Union{}} == Union{}. Did we change that?

@JeffBezanson
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No, I don't think we ever had that.

@vtjnash vtjnash mentioned this issue Sep 11, 2019
Merged
@vtjnash vtjnash added the bug Indicates an unexpected problem or unintended behavior label Jan 27, 2020
vtjnash added a commit that referenced this issue Jul 14, 2020
@vtjnash
squash! remove tuple Type manipulations from convert
2ef2469 
We use an inference barrier here where we know type-intersection will
give an incorrect result to avoid the problem case of #32392.
vtjnash added a commit that referenced this issue Jul 14, 2020
@vtjnash
squash! remove tuple Type manipulations from convert
f3b5e56 
We use an inference barrier here where we know type-intersection will
give an incorrect result to avoid the problem case of #32392.
@vtjnash vtjnash mentioned this issue Jan 5, 2021
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@vtjnash
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vtjnash commented Mar 21, 2023

It turns out that we do have that, but the type system is inconsistent right now. For example, typeintersect(Tuple{Int32}, Tuple{Int64}) gives Union{} not Tuple{Union{}}, even though Tuple{Union{}} is a subtype of both of those. Fixing this by forbidding Tuple{Union{}} from being constructed would help eliminate some complicated inference cases from existing like this (I don't know exactly how this occurred, but somehow it does):

julia> typeintersect(Tuple{typeof(convert), Type{T}, T} where T, Tuple{typeof(convert), Type{<:Symbol}, Any})
Tuple{typeof(convert), Type{T}, T} where T<:Symbol

# ^ could be changed to Tuple{typeof(convert), Type{Symbol}, Symbol}, since Symbol is a leaf type

vtjnash added a commit that referenced this issue Mar 22, 2023
@vtjnash
make Tuple{Union{}} unconstructable
07ced48 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
vtjnash added a commit that referenced this issue Mar 22, 2023
@vtjnash
make Tuple{Union{}} unconstructable
bc9e9b9 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
@vtjnash vtjnash mentioned this issue Mar 22, 2023
Merged
vtjnash added a commit that referenced this issue Mar 22, 2023
@vtjnash
make Tuple{Union{}} unconstructable
c8e197b 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
vtjnash added a commit that referenced this issue Mar 24, 2023
@vtjnash
make Tuple{Union{}} unconstructable
e62b6e3 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
vtjnash added a commit that referenced this issue Apr 4, 2023
@vtjnash
make Tuple{Union{}} unconstructable
0c4fbd8 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
vtjnash added a commit that referenced this issue Apr 7, 2023
@vtjnash
make Tuple{Union{}} unconstructable
ea6bcd5 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
vtjnash added a commit that referenced this issue Apr 9, 2023
@vtjnash
make Tuple{Union{}} unconstructable
8950caf 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
vtjnash added a commit that referenced this issue Apr 10, 2023
@vtjnash
make Tuple{Union{}} unconstructable (#49111)
35e4a1f 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes #32392
- Addresses part of the concerns discussed in
  #24614 (comment)
- Addresses part of the issues presented in
  #26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
Xnartharax pushed a commit to Xnartharax/julia that referenced this issue Apr 19, 2023
@vtjnash @Xnartharax
make Tuple{Union{}} unconstructable (JuliaLang#49111)
311dc64 
Type intersection assumed it was equal to Union{}, so this makes it
unconstructable so that holds true. This is similar to what the
NamedTuple constructor does.

Secondarily, this fixes an inference bug where it would create
Vararg{Union{}} and then incorrectly handle that fieldtype.

- Fixes JuliaLang#32392
- Addresses part of the concerns discussed in
  JuliaLang#24614 (comment)
- Addresses part of the issues presented in
  JuliaLang#26175
- May allow improving jl_type_equality_is_identity
  (https://github.com/JuliaLang/julia/pull/49017/files#diff-882927c6e612596e22406ae0d06adcee88a9ec05e8b61ad81b48942e2cb266e9R986)
- May allow improving intersection (finish_unionall can be more
  aggressive at computing varval for any typevars that appears in
  covariant position and has lb=Union{} and ub=leaf type)
@LilithHafner LilithHafner mentioned this issue Jan 4, 2024
Open
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make Tuple{Union{}} unconstructable JuliaLang/julia
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@vtjnash @JeffBezanson @Keno