From 79aeeda6fa906a07702d0d1c38c59d49d60d3c3c Mon Sep 17 00:00:00 2001
From: Jameson Nash <vtjnash@gmail.com>
Date: Fri, 28 Oct 2022 17:15:18 -0400
Subject: [PATCH] hide kwcall methods from the backtrace

They are not strictly internal, but also not strictly external, so just
assume they should be hidden.

Perhaps, in the future, we should figure out a way to signal directly in
the line number value that this line can be hidden, so only exactly the
inner call gets hidden, but not errors that happen in the kwsorter
itself (for example, for computing default values). Then all of these
could print comparable backtraces (rather than just hiding the kwcall,
as this PR does):

```
julia> f(; a, b) = error()
f (generic function with 1 method)

julia> f()
ERROR: UndefKeywordError: keyword argument `a` not assigned
Stacktrace:
 [1] f()
   @ Main ./REPL[1]:1
 [2] top-level scope
   @ REPL[2]:1

julia> f(b=1)
ERROR: UndefKeywordError: keyword argument `a` not assigned
Stacktrace:
 [1] kwcall(::NamedTuple{(:b,), Tuple{Int64}}, ::typeof(f))
   @ Main ./REPL[1]:1
 [2] top-level scope
   @ REPL[3]:1

julia> f(a=1)
ERROR: UndefKeywordError: keyword argument `b` not assigned
Stacktrace:
 [1] kwcall(::NamedTuple{(:a,), Tuple{Int64}}, ::typeof(f))
   @ Main ./REPL[1]:1
 [2] top-level scope
   @ REPL[4]:1

julia> f(a=1, b=2)
ERROR:
Stacktrace:
 [1] error()
   @ Base ./error.jl:44
 [2] f(; a::Int64, b::Int64)
   @ Main ./REPL[1]:1
 [3] kwcall(::NamedTuple{(:a, :b), Tuple{Int64, Int64}}, ::typeof(f))
   @ Main ./REPL[1]:1
 [4] top-level scope
   @ REPL[5]:1
```

Fix #47319
---
 base/errorshow.jl | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/base/errorshow.jl b/base/errorshow.jl
index 16190d64e01e4..636357827a32a 100644
--- a/base/errorshow.jl
+++ b/base/errorshow.jl
@@ -850,10 +850,11 @@ function process_backtrace(t::Vector, limit::Int=typemax(Int); skipC = true)
             code = lkup.linfo
             if code isa MethodInstance
                 def = code.def
-                if def isa Method
-                    if def.name === :kwcall && def.module === Core
-                        continue
-                    end
+                if def isa Method && def.name !== :kwcall && def.sig <: Tuple{typeof(Core.kwcall),Any,Any,Vararg}
+                    # hide kwcall() methods, which are probably internal keyword sorter methods
+                    # (we print the internal method instead, after demangling
+                    # the argument list, since it has the right line number info)
+                    continue
                 end
             elseif !lkup.from_c
                 lkup.func === :kwcall && continue