Destructuring improvements (#3463)

1 files changed, 33 insertions, 0 deletions

diff --git a/tests/typ/compiler/backtracking.typ b/tests/typ/compiler/backtracking.typ
new file mode 100644
index 00000000..9c3ab8ec
--- /dev/null
+++ b/tests/typ/compiler/backtracking.typ
@@ -0,0 +1,33 @@
+// Ensure that parser backtracking doesn't lead to exponential time consumption.
+// If this regresses, the test suite will not terminate, which is a bit
+// unfortunate compared to a good error, but at least we know something is up.
+//
+// Ref: false
+
+---
+#{
+  let s = "(x: 1) => x"
+  let pat = "(x: {}) => 1 + x()"
+  for _ in range(50) {
+    s = pat.replace("{}", s)
+  }
+  test(eval(s)(), 51)
+}
+
+---
+#{
+  let s = "(x) = 1"
+  let pat = "(x: {_}) = 1"
+  for _ in range(100) {
+    s = pat.replace("_", s)
+  }
+  // Error: 8-9 cannot destructure integer
+  eval(s)
+}
+
+---
+// Test whitespace after memoized part.
+#( (x: () => 1 ) => 1 )
+//     -------
+//     This is memoized and we want to ensure that whitespace after this
+//     is handled correctly.