Compiler crashes after repeated allocation of very large block

[keidax]

Reproducing code:

alias Item = {foo: Int32}

def bar?(item)
  true
end

min = 0
[{foo: 1}, {foo: 2}].each do |item|
  if bar?(item)
    min = [min, item[:foo]]
  end
end

pp min

This is actually a mistake, because I meant to type min = [min, item[:foo]].min? But it still surprised me when I realized this causes a compiler crash.

The output of crystal build looks like

GC Warning: Repeated allocation of very large block (appr. size 67112960):
	May lead to memory leak and poor performance

repeated several times followed by an OverflowError.

This looks pretty similar to #2257, but that issue is old and closed.

This is on Arch Linux.

$ crystal -v
Crystal 0.35.1 (2020-10-17)

LLVM: 10.0.1
Default target: x86_64-pc-linux-gnu

[bcardiff]

The compiler issue here is that the "generic type too nested" error is not raised and the OOM happens during compile time.

Compiling the above program should behave the same as the following one.

min = 0

2.times do
  min = [min, 1]
end

$ crystal build foo.cr
Showing last frame. Use --error-trace for full trace.

In foo.cr:126:9

 126 | min = [min, 1]
             ^
Error: generic type too nested: Array(Array(Array(Array(Array( ... stripped ... | Int32) | Int32) | Int32)