Regression in cleanup trannsformer

[straight-shoota]

The current nightly build of crinja shows a compiler regression in master. The build with a compiler at master fails, while 0.26.1 is fine.

This was probably introduced by #6659

I couldn't exactly pinpoint the failing part yet (the code base is quite large).
But it is reproducible with:

$ git clone https://github.com/straight-shoota/crinja && cd crinja
$ crystal-master spec spec/lib/filter_spec.cr

Callstack:

Nil assertion failed at /crystal/src/compiler/crystal/semantic/bindings.cr:530 (Exception)
  from /crystal/src/nil.cr:107:5 in 'not_nil!'
  from /crystal/src/compiler/crystal/semantic/bindings.cr:0:5 in 'program'
  from /crystal/src/compiler/crystal/semantic/bindings.cr:539:26 in 'update'
  from /crystal/src/compiler/crystal/semantic/bindings.cr:532:5 in 'update'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:746:7 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:380:7 in 'transform_many'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:262:10 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:258:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:258:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:138:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:324:7 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:7 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:263:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:138:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:461:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:299:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:138:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:461:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:299:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:138:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/transformer.cr:10:7 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:167:16 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:138:9 in 'transform'
  from /crystal/src/compiler/crystal/syntax/transformer.cr:7:14 in 'transform'
  from /crystal/src/compiler/crystal/semantic/cleanup_transformer.cr:9:14 in 'cleanup'
  from /crystal/src/compiler/crystal/semantic/main_visitor.cr:13:7 in 'visit_main'
  from /crystal/src/compiler/crystal/semantic/main_visitor.cr:5:5 in 'visit_main:process_finished_hooks:cleanup'
  from /crystal/src/compiler/crystal/semantic.cr:22:7 in 'semantic'
  from /crystal/src/compiler/crystal/compiler.cr:152:7 in 'compile'
  from /crystal/src/compiler/crystal/command/spec.cr:74:14 in 'spec'
  from /crystal/src/compiler/crystal/command.cr:88:7 in 'run'
  from /crystal/src/compiler/crystal/command.cr:46:5 in 'run'
  from /crystal/src/compiler/crystal/command.cr:45:3 in 'run'
  from /crystal/src/compiler/crystal.cr:8:1 in '__crystal_main'
  from /crystal/src/crystal/main.cr:97:5 in 'main_user_code'
  from /crystal/src/crystal/main.cr:86:7 in 'main'
  from /crystal/src/crystal/main.cr:106:3 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

/cc @makenowjust

[makenowjust]

Reproducible examples:

def pending(&block)
end

pending do
  {"foo" * 20}
end

And

def pending(&block)
end

pending do
  {s: "foo" * 20}
end

To compile the first example is failed on 0.26.1 too. That's interesting.