Compiler bug with @id : Int32 = (@@id += 1)

[I3oris]

Hello Crystal team!

I've found a bug when I write:

class Foo
  @@id = 0
  @id : Int32 = (@@id += 1)
end

Foo.new

This gives:

BUG: `@@id = @@id + 1` at /home/rwby/bug.cr:4:18 has no type (Exception)
  from ../../crystal/src/compiler/crystal/semantic/bindings.cr:13:18 in 'run_instance_vars_initializers'
  from ../../crystal/src/compiler/crystal/codegen/codegen.cr:1912:7 in 'allocate_aggregate'
  from ../../crystal/src/compiler/crystal/codegen/primitives.cr:702:5 in 'codegen_primitive_allocate'
  from ../../crystal/src/compiler/crystal/codegen/primitives.cr:27:15 in 'codegen_primitive'
  from ../../crystal/src/compiler/crystal/codegen/call.cr:419:7 in 'visit'
  from ../../crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from ../../crystal/src/compiler/crystal/codegen/codegen.cr:2188:9 in 'visit'
  from ../../crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from ../../crystal/src/compiler/crystal/codegen/codegen.cr:628:9 in 'accept'
  from ../../crystal/src/compiler/crystal/codegen/codegen.cr:2193:7 in 'codegen_fun'
  from ../../crystal/src/compiler/crystal/codegen/fun.cr:51:3 in 'target_def_fun'
  from ../../crystal/src/compiler/crystal/codegen/call.cr:424:5 in 'visit'
  from ../../crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from ../../crystal/src/compiler/crystal/codegen/codegen.cr:628:9 in 'accept'
  from ../../crystal/src/compiler/crystal/codegen/codegen.cr:2158:7 in 'codegen'
  from ../../crystal/src/compiler/crystal/compiler.cr:172:16 in 'compile'
  from ../../crystal/src/compiler/crystal/command.cr:209:5 in 'run_command'
  from ../../crystal/src/compiler/crystal/command.cr:62:5 in 'run'
  from ../../crystal/src/compiler/crystal.cr:11:1 in '__crystal_main'
  from ../../crystal/src/crystal/main.cr:105:5 in 'main'
  from src/env/__libc_start_main.c:94:2 in 'libc_start_main_stage2'
Error: you've found a bug in the Crystal compiler. Please open an issue, including source code that will allow us to reproduce the bug: https://github.com/crystal-lang/crystal/issues

This bug look a bit like #8802 in witch the discussion is interesting, I hope that issue will help you to handle problems with @@calss_vars.

Version :

Crystal 0.35.1 [5999ae29b] (2020-06-19)

LLVM: 8.0.0
Default target: x86_64-unknown-linux-gnu