Crystal: BUG: trying to assign … (Exception)

[serge-name]

Hello. When I was playing with a code I received a message:

BUG: trying to assign Array(SomeClass::InnerClass(UInt16)) <- Array(SomeClass::InnerClass(T)) (Exception)
  from ???
[… dupes skipped …]
  from ???
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

The code to reproduce:

class SomeClass(T)
  class InnerClass(T)
  end

  @foo = [] of InnerClass(T)
end


class SomeClassDesc(T) < SomeClass(T)
  class SomeClass::InnerClass(T)
  end
end

foo = SomeClassDesc(UInt16).new

OS:

Debian GNU/Linux 9.5 (stretch)

Crystal version:

Crystal 0.25.1 [b782738ff] (2018-06-27)

LLVM: 4.0.0
Default target: x86_64-unknown-linux-gnu

The bug also can be reproduced on master branch with a detailed backtrace:

Crystal 0.25.1+86 [d454f6973] (2018-08-04)

LLVM: 4.0.1
Default target: x86_64-pc-linux-gnu

BUG: trying to assign Array(SomeClass::InnerClass(UInt16)) <- Array(SomeClass::InnerClass(T)) (Exception)
  from /tmp/crystal/src/compiler/crystal/codegen/cast.cr:281:5 in 'assign_distinct'
  from /tmp/crystal/src/compiler/crystal/codegen/cast.cr:85:7 in 'assign'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:1843:11 in 'run_instance_vars_initializers_non_recursive'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:1809:7 in 'run_instance_vars_initializers'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:1814:9 in 'run_instance_vars_initializers'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:1808:7 in 'run_instance_vars_initializers'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:1794:7 in 'allocate_aggregate'
  from /tmp/crystal/src/compiler/crystal/codegen/primitives.cr:414:5 in 'codegen_primitive_allocate'
  from /tmp/crystal/src/compiler/crystal/codegen/primitives.cr:23:15 in 'codegen_primitive'
  from /tmp/crystal/src/compiler/crystal/codegen/call.cr:403:7 in 'codegen_call'
  from /tmp/crystal/src/compiler/crystal/codegen/call.cr:35:7 in 'visit'
  from /tmp/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:2049:7 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:928:9 in 'codegen_assign'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:892:7 in 'visit'
  from /tmp/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:2049:7 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:592:9 in 'visit'
  from /tmp/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:2049:7 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/fun.cr:142:9 in 'codegen_fun'
  from /tmp/crystal/src/compiler/crystal/codegen/fun.cr:51:3 in 'codegen_fun'
  from /tmp/crystal/src/compiler/crystal/codegen/fun.cr:8:54 in 'target_def_fun'
  from /tmp/crystal/src/compiler/crystal/codegen/call.cr:408:12 in 'codegen_call'
  from /tmp/crystal/src/compiler/crystal/codegen/call.cr:35:7 in 'visit'
  from /tmp/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:2049:7 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:928:9 in 'codegen_assign'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:892:7 in 'visit'
  from /tmp/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:2049:7 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:592:9 in 'visit'
  from /tmp/crystal/src/compiler/crystal/syntax/visitor.cr:27:12 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:2049:7 in 'accept'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:65:7 in 'codegen'
  from /tmp/crystal/src/compiler/crystal/codegen/codegen.cr:63:5 in 'codegen:debug:single_module'
  from /tmp/crystal/src/compiler/crystal/compiler.cr:22:7 in 'codegen'
  from /tmp/crystal/src/compiler/crystal/compiler.cr:145:16 in 'compile'
  from /tmp/crystal/src/compiler/crystal/command.cr:260:7 in 'compile'
  from /tmp/crystal/src/compiler/crystal/command.cr:179:14 in 'run_command'
  from /tmp/crystal/src/compiler/crystal/command.cr:87:7 in 'run'
  from /tmp/crystal/src/compiler/crystal/command.cr:48:5 in 'run'
  from /tmp/crystal/src/compiler/crystal/command.cr:47:3 in 'run'
  from /tmp/crystal/src/compiler/crystal.cr:8:1 in '__crystal_main'
  from /tmp/crystal/src/crystal/main.cr:104:5 in 'main_user_code'
  from /tmp/crystal/src/crystal/main.cr:93:7 in 'main'
  from /tmp/crystal/src/crystal/main.cr:133:3 in 'main'
  from __libc_start_main
  from _start
  from ???
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

[hanyuone]

Simplified example (carc.in link here):

class InnerClass(T)
end

class SomeClass(T)
  @foo = [] of InnerClass(T)
end

class NewClass(T) < SomeClass(T)
end

foo = NewClass(UInt16).new

This is probably another generics issue.

[serge-name]

The code you provided is simpler and gives same result as mine (on both 0.25.1 and master).

Thank you.

[serge-name]

Still being reproduced on

Crystal 0.27.0 [c9d1eef8f] (2018-11-01)

LLVM: 4.0.0
Default target: x86_64-unknown-linux-gnu

[Blacksmoke16]

Probably related: https://play.crystal-lang.org/#/r/8rzu

abstract struct Comparison(T)
  getter type : T.class = T

  def initialize(@value : T); end
end

struct GreaterThan(T) < Comparison(T)
end

pp GreaterThan(Int32).new 1 # => BUG: trying to assign Int32.class <- T.class (Exception)

[matthewmcgarvey]

Just ran into this one on 0.35.1

My minimal reproduction:

class Dog(T)
  getter friends = Array(Dog(T)).new
end

class GermanShepherd(T) < Dog(T)
end

GermanShepherd(String).new