Avoid printing values of keyword arguments while displaying a MethodError

[jishnub]

Related to this discourse thread

MWE:

julia> f(a::Int; b = nothing) = a
f (generic function with 1 method)

julia> f(2.0, b = zeros(10))
ERROR: MethodError: no method matching f(::Float64; b=[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0])
Closest candidates are:
  f(::Int64; b) at REPL[1]:1
Stacktrace:
 [1] top-level scope
   @ REPL[2]:1

The value of the keyword argument has nothing to do with the error, and only adds visual clutter. In some cases, displaying the keyword arguments might take up considerable screen space and be time-consuming.

In case there is a mismatch in the type of the keyword argument, the error thrown is a TypeError, which doesn't show the value of the argument. Arguably, this is the case that might benefit from the values being displayed.

julia> h(a::Int; b::Float64 = 0.0) = a
h (generic function with 1 method)

julia> h(2, b = 4)
ERROR: TypeError: in keyword argument b, expected Float64, got a value of type Int64
Stacktrace:
 [1] top-level scope
   @ REPL[9]:1

[JeffBezanson]

Agree; it doesn't make sense to show the values for keyword arguments and not positional arguments.

[skleinbo]

FWIW, #16669 introduced the behavior.

julia/base/errorshow.jl

Lines 274 to 276 in 59d1d54

	for (i, (k, v)) in enumerate(kwargs)
	print(io, k, "=")
	show(IOContext(io, :limit => true), v)

[KristofferC]

The behavior is explicitly discussed here #16669 (comment). Possible fix #45255.