[Bug] Overflow in 128-bit negative integers

[akadusei]

This is a bug, according to the compiler:

Code

[playground]

-3_i128

Output

Overflow (OverflowError)
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from ???
  from __crystal_main
  from main
  from __libc_start_main
  from _start
  from ???
Error: you've found a bug in the Crystal compiler. Please open an issue,...

This affects only negative integers.

The bug seems to be a regression introduced in v0.27.2, according to the Crystal playground. It worked fine before.

[jhass]

Trace with symbols:

Arithmetic overflow (OverflowError)
  from __crystal_raise_overflow
  from LLVM::Type#const_int<Int64>:LLVM::Value
  from Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil
  from Crystal::ASTNode+@Crystal::ASTNode#accept<Crystal::CodeGenVisitor>:Nil
  from Crystal::Compiler#codegen<Crystal::Program, Crystal::ASTNode+, Array(Crystal::Compiler::Source), String>:(Tuple(Array(Crystal::Compiler::CompilationUnit), Array(String)) | Nil)
  from Crystal::Compiler#compile<Array(Crystal::Compiler::Source), String>:Crystal::Compiler::Result
  from Crystal::Command#run:(Bool | Crystal::Compiler::Result | Nil)
  from main

[jkthorne]

I dont think 128 bit integers are fully implemented yet. I think this is a problem here. Also there is a PR to add 128 bit support. Most of the work was dont in another branch it is just a bit project.