julia> struct A end
julia> struct B end
julia> const AB = Union{A, B}
AB (alias for Union{A, B})
julia> f(::T, ::T) where {T<:AB} = false
f (generic function with 1 method)
julia> g(a, b) = (@nospecialize; if a isa AB && b isa AB; f(a, b); end;)
g (generic function with 1 method)
julia> g(A(), A())
false
julia> g(A(), B())
ERROR: fatal error in type inference (type bound)
Stacktrace:
[1] g(a::Any, b::Any)
@ Main ./REPL[15]:1
[2] top-level scope
@ REPL[17]:1
julia> versioninfo()
Julia Version 1.7.0-DEV.184
Commit 8e0183f2b6 (2020-12-28 17:36 UTC)
