Compiler Bug when class constant is Regex that references class member of same name

[jfharrigan]

The compiler reports a compiler bug for the following code:

class Pattern
  @@A = "asdf"
  A = /#{@@A}/
end
puts Pattern::A

I can only trigger this bug if the constant and member have the same name.

crystal build test.cr

Module validation failed: Function return type does not match operand type of return inst!
  ret %String** @"Pattern::A", !dbg !74
 %Regex** (Exception)
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???

crystal -v

Crystal 0.29.0 [fbfe8b62f] (2019-06-05)
LLVM: 4.0.0
Default target: x86_64-unknown-linux-gnu

[straight-shoota]

@@A should not be a valid name for a class variable.

[HertzDevil]

The internal error went away since 1.8 due to changes to regex creation, but now running the program crashes because both constants and class variables are initialized or read using the same LLVM functions (~Pattern::A:init in this case). This is the code that lexes instance or class variables (and globals too, which are still allowed in libs):

crystal/src/compiler/crystal/syntax/lexer.cr

Lines 2669 to 2679 in c97c20e

	private def consume_variable(token_type : Token::Kind, start)
	if ident_start?(current_char)
	while ident_part?(next_char)
	# Nothing to do
	end
	@token.type = token_type
	@token.value = string_range_from_pool(start)
	else
	unknown_token
	end
	end