Bytes[1, 2] is broken when used in a class

[bew]

https://carc.in/#/r/36qg

STDOUT.write Bytes[1, 2] # works OK

class Foo
  def self.bytes
    Bytes['a'.ord, 97]
  end
end

STDOUT.write Foo.bytes   # compile error

Gives:

Error in bytes_slice.cr:9: instantiating 'Foo:Class#bytes()'

STDOUT.write Foo.bytes
                 ^~~~~

in bytes_slice.cr:5: expanding macro

    Bytes['a'.ord, 97]
         ^

in /usr/lib/crystal/slice.cr:34: undefined constant T

    {% if @type.name != "Slice(T)" && T < Number %}
                                      ^

The macro expansion is looking for a T in Foo.

This is visible with this example (https://carc.in/#/r/36qi):

class Bar(T) # Here is a T !
  def self.bytes
    Bytes['a'.ord, 97]
  end
end

STDOUT.write Bar(UInt8).bytes # compiles OK, but this is wrong!

Going back in time with carc.in, it seems to break on 0.19.0 release.

[makenowjust]

Bytes free version:

class Foo(T)
  macro [](*foo)
    {% puts T %}
  end
end

alias FooInt32 = Foo(Int32)

class Bar
  def self.foo
    FooInt32[1, 2, 3]
  end
end

p FooInt32[1, 2, 3]
# => Int32
p Bar.foo
# compilation error: undefined constant T

It means there is a bug about type aliases and macros.