Orphaned Decrement Error after sorting a TypedArray

[mhonert]

Hi,

I am currently writing a chess engine in AssemblyScript and for optimization purposes I wanted to replace some Arrays with TypedArrays.

Unfortunately, after the change some of my unit tests started to fail with error "An orphaned decrement has occurred...".

After some debugging, I noticed that the error seems to occur when sorting the array.
Here is a minimal code snippet to reproduce the error:

function reproduceBug(): i32 {
  let moves = new Int32Array(1);
  moves[0] = 1;
  moves.sort();
  return moves[0];
}

describe("Bug?", () => {
  it("causes error 'An orphaned decrement has occured'", () => {
    const result = reproduceBug();
    expect(result).toBe(1);
  });
})

Here is the error message when running the test with as-pect:

[Error]: Orphaned Decrement Error: An orphaned decrement has occurred at block: 4784
[Stack]:    at ~lib/rt/pure/decrement (wasm-function[54]:23)
                at ~lib/rt/pure/__release (wasm-function[55]:13)
                at assembly/__tests__/util.spec/reproduceBug (wasm-function[127]:41)
                at start:assembly/__tests__/util.spec~anonymous|5~anonymous|0 (wasm-function[129]:3)
                at node_modules/@as-pect/assembly/assembly/internal/call/__call (wasm-function[133]:7)

AssemblyScript version: 0.8.1

[MaxGraey]

Can confirm. This happening only with Typed Arrays when size of array <= 2