`MethodError` thrown while preparing to throw `InexactError` in conversion of `Rational` to `Integer` or `Complex` to `Real`

[nsajko]

Minimal reproducer:

julia> struct A <: Integer end

julia> struct B <: Integer end

julia> Union{A,B}(1//2)
ERROR: MethodError: no method matching nameof(::Type{Union{A, B}})
The function `nameof` exists, but no method is defined for this combination of argument types.

Closest candidates are:
  nameof(::Core.IntrinsicFunction)
   @ Base reflection.jl:2369
  nameof(::Module)
   @ Base essentials.jl:401
  nameof(::UnionAll)
   @ Base reflection.jl:343
  ...

Stacktrace:
 [1] Union{A, B}(x::Rational{Int64})
   @ Base ./rational.jl:151
 [2] top-level scope
   @ REPL[3]:1

It's not valid to call nameof on an arbitrary subtype of Integer, because it may be an Union:

julia/base/rational.jl

Lines 149 to 152 in 945517b

	Bool(x::Rational) = x==0 ? false : x==1 ? true :
	throw(InexactError(:Bool, Bool, x)) # to resolve ambiguity
	(::Type{T})(x::Rational) where {T<:Integer} = (isinteger(x) ? convert(T, x.num)::T :
	throw(InexactError(nameof(T), T, x)))

It seems like this could be fixed by simply replacing the nameof call with :convert.

[nsajko]

The same issue as for Rational is present for Complex:

julia/base/complex.jl

Lines 44 to 45 in e52a46c

	(::Type{T})(z::Complex) where {T<:Real} =
	isreal(z) ? T(real(z))::T : throw(InexactError(nameof(T), T, z))

[nsajko]

Also with BigFloat:

julia/base/mpfr.jl

Lines 410 to 413 in 467ab85

	function (::Type{T})(x::BigFloat) where T<:Integer
	isinteger(x) || throw(InexactError(nameof(T), T, x))
	trunc(T,x)
	end