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InteractiveUtils: support syntax found in stacktraces for introspection macros#58222

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aviatesk merged 2 commits intomasterfrom
serenity4/interactiveutils-stacktrace-syntax
Apr 26, 2025
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InteractiveUtils: support syntax found in stacktraces for introspection macros#58222
aviatesk merged 2 commits intomasterfrom
serenity4/interactiveutils-stacktrace-syntax

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@serenity4 serenity4 commented Apr 24, 2025 •
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Continuing the work done at #57909, this PR adds support for the following syntax:

@code_typed f(some_undef_var::Int) # some_undef_var is ignored, only the annotation is used
@code_typed f(; x::Int) # same here, the name is used but not the value

This should allow us to copy and paste signatures found in stacktraces, such as

julia> f(x; y = 3) = error()
f (generic function with 1 method)

julia> f(1)
ERROR: 
Stacktrace:
 [1] error()
   @ Base ./error.jl:45
 [2] f(x::Int64; y::Int64)
   @ Main ./REPL[40]:1
 [3] top-level scope
   @ REPL[41]:1
   
julia> asin(-2)
ERROR: DomainError with -2.0:
asin(x) is not defined for |x| > 1.
Stacktrace:
 [1] asin_domain_error(x::Float64)
   @ Base.Math ./special/trig.jl:429
 [2] asin(x::Float64)
   @ Base.Math ./special/trig.jl:443

where any function call may be copied and pasted into @code_typed, @edit etc as is, provided that the function and argument types are defined in the active module (i.e. Main).

Thanks @topolarity for the idea.

topolarity
topolarity approved these changes Apr 24, 2025
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Thank you!

I have spent an embarrassing amount of time parsing a method signature to see which foo::Int64 was part of a NamedTuple and which needed to be deleted as part of the arguments

This looks very convenient 👍

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serenity4 commented Apr 24, 2025 •
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Good observation! I just tried with named tuples to make sure, it works well:

julia> f(x, y; z = 3) = x + y.a + z
f (generic function with 1 method)

julia> f((; k = current_task(), l = 3), (; a = 1, b = "hello"))
ERROR: MethodError: no method matching +(::@NamedTuple{k::Task, l::Int64}, ::Int64)
The function `+` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  +(::Any, ::Any, ::Any, ::Any...)
   @ Base operators.jl:643
  +(::BigInt, ::Union{Int16, Int32, Int64, Int8})
   @ Base gmp.jl:554
  +(::Base.CoreLogging.LogLevel, ::Integer)
   @ Base logging/logging.jl:132
  ...

Stacktrace:
 [1] +
   @ ./operators.jl:643 [inlined]
 [2] f(x::@NamedTuple{k::Task, l::Int64}, y::@NamedTuple{a::Int64, b::String}; z::Int64)
   @ Main ./REPL[7]:1
 [3] top-level scope
   @ REPL[8]:1
 [4] top-level scope
   @ REPL:1

julia> @code_typed f(x::@NamedTuple{k::Task, l::Int64}, y::@NamedTuple{a::Int64, b::String}; z::Int64)
CodeInfo(
1 ─      nothing::Nothing
│   %2 =   builtin Core.getfield(@_2, :z)::Int64
│        nothing::Nothing
│        nothing::Nothing
│           invoke Main.:(var"#f#3")(%2::Int64, @_3::typeof(f), x::@NamedTuple{k::Task, l::Int64}, y::@NamedTuple{a::Int64, b::String})::Union{}
└──      unreachable
) => Union{}

(now, if only we could step through that invoke...)

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aviatesk commented Apr 25, 2025

This is a very nice enhancement, thanks!
I think we also want to update the documentation or the NEWS file?

BTW this will really improve JET's usability.
With this PR's feature, we can launch Cthulhu session for a specific method call copy-and-pasting its signature from JET's virtual stacktrace output, which will make debugging a lot easier:

julia> using JET, Cthulhu

julia> @report_call sum("julia")
═════ 2 possible errors found ═════
┌ sum(a::String) @ Base ./reduce.jl:553
│┌ sum(a::String; kw::@Kwargs{}) @ Base ./reduce.jl:553
││┌ sum(f::typeof(identity), a::String) @ Base ./reduce.jl:524
│││┌ sum(f::typeof(identity), a::String; kw::@Kwargs{}) @ Base ./reduce.jl:524
││││┌ mapreduce(f::typeof(identity), op::typeof(Base.add_sum), itr::String) @ Base ./reduce.jl:299
│││││┌ mapreduce(f::typeof(identity), op::typeof(Base.add_sum), itr::String; kw::@Kwargs{}) @ Base ./reduce.jl:299
││││││┌ mapfoldl(f::typeof(identity), op::typeof(Base.add_sum), itr::String) @ Base ./reduce.jl:167
│││││││┌ mapfoldl(f::typeof(identity), op::typeof(Base.add_sum), itr::String; init::Base._InitialValue) @ Base ./reduce.jl:167
││││││││┌ mapfoldl_impl(f::typeof(identity), op::typeof(Base.add_sum), nt::Base._InitialValue, itr::String) @ Base ./reduce.jl:36
│││││││││┌ foldl_impl(op::Base.BottomRF{typeof(Base.add_sum)}, nt::Base._InitialValue, itr::String) @ Base ./reduce.jl:40
││││││││││┌ _foldl_impl(op::Base.BottomRF{typeof(Base.add_sum)}, init::Base._InitialValue, itr::String) @ Base ./reduce.jl:54
│││││││││││┌ (::Base.BottomRF{typeof(Base.add_sum)})(acc::Char, x::Char) @ Base ./reduce.jl:78
││││││││││││┌ add_sum(x::Char, y::Char) @ Base ./reduce.jl:16
│││││││││││││ no matching method found `+(::Char, ::Char)`: (x::Char + y::Char)
││││││││││││└────────────────────
│││││││││┌ foldl_impl(op::Base.BottomRF{typeof(Base.add_sum)}, nt::Base._InitialValue, itr::String) @ Base ./reduce.jl:41
││││││││││┌ reduce_empty_iter(op::Base.BottomRF{typeof(Base.add_sum)}, itr::String) @ Base ./reduce.jl:372
│││││││││││┌ reduce_empty_iter(op::Base.BottomRF{typeof(Base.add_sum)}, itr::String, ::Base.HasEltype) @ Base ./reduce.jl:373
││││││││││││┌ reduce_empty(op::Base.BottomRF{typeof(Base.add_sum)}, ::Type{Char}) @ Base ./reduce.jl:349
│││││││││││││┌ reduce_empty(::typeof(Base.add_sum), ::Type{Char}) @ Base ./reduce.jl:342
││││││││││││││┌ reduce_empty(::typeof(+), ::Type{Char}) @ Base ./reduce.jl:335
│││││││││││││││ no matching method found `zero(::Type{Char})`: zero(T::Type{Char})
││││││││││││││└────────────────────


julia> @descend Base. mapfoldl_impl(f::typeof(identity), op::typeof(Base.add_sum), nt::Base._InitialValue, itr::String)
mapfoldl_impl(f::F, op::OP, nt, itr) where {F, OP} @ Base ~/julia/julia/base/reduce.jl:34
...

@aviatesk aviatesk merged commit 142f419 into master Apr 26, 2025
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@aviatesk aviatesk deleted the serenity4/interactiveutils-stacktrace-syntax branch April 26, 2025 19:33
LebedevRI pushed a commit to LebedevRI/julia that referenced this pull request May 2, 2025
@serenity4 @LebedevRI
InteractiveUtils: support syntax found in stacktraces for introspecti…
1bf634f 
…on macros (JuliaLang#58222)

Continuing the work done at JuliaLang#57909, this PR adds support for the
following syntax:
```julia
@code_typed f(some_undef_var::Int) # some_undef_var is ignored, only the annotation is used
@code_typed f(; x::Int) # same here, the name is used but not the value
```
This should allow us to copy and paste signatures found in stacktraces,
such as
```julia
julia> f(x; y = 3) = error()
f (generic function with 1 method)

julia> f(1)
ERROR: 
Stacktrace:
 [1] error()
   @ Base ./error.jl:45
 [2] f(x::Int64; y::Int64)
   @ Main ./REPL[40]:1
 [3] top-level scope
   @ REPL[41]:1
   
julia> asin(-2)
ERROR: DomainError with -2.0:
asin(x) is not defined for |x| > 1.
Stacktrace:
 [1] asin_domain_error(x::Float64)
   @ Base.Math ./special/trig.jl:429
 [2] asin(x::Float64)
   @ Base.Math ./special/trig.jl:443
```

where any function call may be copied and pasted into `@code_typed`,
`@edit` etc as is, provided that the function and argument types are
defined in the active module (i.e. `Main`).

Thanks @topolarity for the idea.

---------

Co-authored-by: Cédric Belmant <cedric.belmant@juliahub.com>
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