Fix #11141 broken sp corrector

tests/functional/lang-gc/issue-11141-gc-coroutine-test.nix

@@ -0,0 +1,65 @@
+
+# Run:
+# GC_INITIAL_HEAP_SIZE=$[1024 * 1024] NIX_SHOW_STATS=1 nix eval -f gc-coroutine-test.nix  -vvvv
+
+let
+  inherit (builtins)
+    foldl'
+    isList
+    ;
+
+  # Generate a tree of numbers, n deep, such that the numbers add up to (1 + salt) * 10^n.
+  # The salting makes the numbers all different, increasing the likelihood of catching
+  # any memory corruptions that might be caused by the GC or otherwise.
+  garbage = salt: n:
+    if n == 0
+    then [(1 + salt)]
+    else [
+      (garbage (10 * salt + 1) (n - 1))
+      (garbage (10 * salt - 1) (n - 1))
+      (garbage (10 * salt + 2) (n - 1))
+      (garbage (10 * salt - 2) (n - 1))
+      (garbage (10 * salt + 3) (n - 1))
+      (garbage (10 * salt - 3) (n - 1))
+      (garbage (10 * salt + 4) (n - 1))
+      (garbage (10 * salt - 4) (n - 1))
+      (garbage (10 * salt + 5) (n - 1))
+      (garbage (10 * salt - 5) (n - 1))
+    ];
+
+  pow = base: n:
+    if n == 0
+    then 1
+    else base * (pow base (n - 1));
+
+  sumNestedLists = l:
+    if isList l
+    then foldl' (a: b: a + sumNestedLists b) 0 l
+    else l;
+
+in
+  assert sumNestedLists (garbage 0 3) == pow 10 3;
+  assert sumNestedLists (garbage 0 6) == pow 10 6;
+  builtins.foldl'
+    (a: b:
+      assert
+        "${
+          builtins.path {
+            path = ./src;
+            filter = path: type:
+              # We're not doing common subexpression elimination, so this reallocates
+              # the fairly big tree over and over, producing a lot of garbage during
+              # source filtering, whose filter runs in a coroutine.
+              assert sumNestedLists (garbage 0 3) == pow 10 3;
+              true;
+          }
+        }"
+          == "${./src}";
+
+      # These asserts don't seem necessary, as the lambda value get corrupted first
+      assert a.okay;
+      assert b.okay;
+      { okay = true; }
+    )
+    { okay = true; }
+    [ { okay = true; } { okay = true; } { okay = true; } ]