Interpreter: invalid memory access with StaticArray#sort_by StaticArray#unstable_sort_by

[cyangle]

Bug Report

Example code:

a = StaticArray["foo", "a", "hello"]
puts a.unstable_sort_by(&.size)
puts a.sort_by(&.size)

Interpreter crashes with invalid memory access error:

Invalid memory access (signal 11) at address 0x8
[0x56388624e046] *Exception::CallStack::print_backtrace:Nil +118 in /home/chao/git/personal/crystal/.build/crystal
[0x56388621b34a] ~procProc(Int32, Pointer(LibC::SiginfoT), Pointer(Void), Nil) +330 in /home/chao/git/personal/crystal/.build/crystal
[0x7f10a9530520] ?? +139709536994592 in /lib/x86_64-linux-gnu/libc.so.6
[0x7f10a968e995] ?? +139709538429333 in /lib/x86_64-linux-gnu/libc.so.6
[0x563886241d1c] *Pointer(UInt8) +108 in /home/chao/git/personal/crystal/.build/crystal
[0x563886241ca1] *Pointer(UInt8) +17 in /home/chao/git/personal/crystal/.build/crystal
[0x563886241e71] *Pointer(UInt8) +17 in /home/chao/git/personal/crystal/.build/crystal
[0x563887159e27] *Crystal::Repl::Interpreter#interpret<Crystal::ASTNode+, Crystal::Type+>:Crystal::Repl::Value +394199 in /home/chao/git/personal/crystal/.build/crystal
[0x5638870f8fc9] *Crystal::Repl::Interpreter#interpret<Crystal::ASTNode+, Hash(String, Crystal::MetaVar)>:Crystal::Repl::Value +2281 in /home/chao/git/personal/crystal/.build/crystal
[0x5638876d8d3a] *Crystal::Repl#interpret<Crystal::Expressions>:Crystal::Repl::Value +106 in /home/chao/git/personal/crystal/.build/crystal
[0x5638876d8a56] *Crystal::Repl#interpret_and_exit_on_error<Crystal::Expressions>:Crystal::Repl::Value +38 in /home/chao/git/personal/crystal/.build/crystal
[0x5638876d9626] *Crystal::Repl#run_file<String, Array(String)>:Crystal::Repl::Value +230 in /home/chao/git/personal/crystal/.build/crystal
[0x563887615075] *Crystal::Command#repl:(Crystal::Repl::Value | Nil) +1669 in /home/chao/git/personal/crystal/.build/crystal
[0x56388760eb46] *Crystal::Command#run:(Bool | Crystal::Repl::Value | Nil) +1414 in /home/chao/git/personal/crystal/.build/crystal
[0x56388760e43c] *Crystal::Command::run<Array(String)>:(Bool | Crystal::Repl::Value | Nil) +44 in /home/chao/git/personal/crystal/.build/crystal
[0x56388760e3ae] *Crystal::Command::run:(Bool | Crystal::Repl::Value | Nil) +46 in /home/chao/git/personal/crystal/.build/crystal
[0x5638861f89ec] __crystal_main +2668 in /home/chao/git/personal/crystal/.build/crystal
[0x563886401485] *Crystal::main_user_code<Int32, Pointer(Pointer(UInt8))>:Nil +37 in /home/chao/git/personal/crystal/.build/crystal
[0x5638864013ce] *Crystal::main<Int32, Pointer(Pointer(UInt8))>:Int32 +62 in /home/chao/git/personal/crystal/.build/crystal
[0x563886206026] main +6 in /home/chao/git/personal/crystal/.build/crystal
[0x7f10a9517d90] ?? +139709536894352 in /lib/x86_64-linux-gnu/libc.so.6
[0x7f10a9517e40] __libc_start_main +128 in /lib/x86_64-linux-gnu/libc.so.6
[0x5638861f7eb5] _start +37 in /home/chao/git/personal/crystal/.build/crystal
[0x0] ???

[asterite]

It seems there's a dup call inside StaticArray that doesn't return what it should.

Here's a reduction:

struct Foo
  def initialize(@x : Int32)
  end

  def foo
    dup
  end
end

a = Foo.new(1)
b = a.foo
puts b # Foo(@x=65748992) ???

When I change dup to self in StaticArray it starts working fine, so there must be something wrong in the interpreter regarding dup. It's strange because dup just returns self.

Here's another reduction that doesn't depend on dup:

struct Foo
  def initialize(@x : Int32)
  end

  def foo
    me
  end

  def me
    self
  end
end

a = Foo.new(1)
b = a.foo
puts b # => Foo(@x=70352896)

This should be easy to fix. I'll check it later.