[test] SWIFT_NPE: pin out-of-scope shapes stay silent

dulmarod · meta-codesync[bot] · commit ce94c420ab1e · 2026-06-04T09:14:53.000-07:00
Summary:
Adds corpus fixtures pinning that three Swift shapes which look superficially
like force-unwraps do NOT fire `SWIFT_NPE`, guarding against accidental
over-reporting as the checker evolves:

- `tryForceUnwrap_noSwiftNPE` — `try!` of a throwing call is an unhandled-error
  force-try, not a nil dereference. It lowers to `swift_unexpectedError` on the
  `error != nil` branch, a different shape from the Optional force-unwrap trap
  (`__sil_assert_fail` on `eq(disc, 0)`). The recogniser correctly leaves it
  alone, so it must stay out of `SWIFT_NPE` scope.
- `optionalMap_good` / `optionalFlatMap_good` — `.map` / `.flatMap` propagate the
  Optional without force-unwrapping, so they can never trap.

All three produce no report (the test baseline is unchanged), documenting the
intended silence.

Reviewed By: davidpichardie

Differential Revision: D107524914

fbshipit-source-id: 4c545d5e2d74d84c69f079b707445aa179b67b41
diff --git a/infer/tests/codetoanalyze/swift/interop-pulse/IUODerefTests.swift b/infer/tests/codetoanalyze/swift/interop-pulse/IUODerefTests.swift
@@ -244,3 +244,32 @@ func guardedUnwrap_good(_ x: Int?) -> Int {
 func interprocGuardedUnwrap_good() {
   _ = guardedUnwrap_good(nil)
 }
+
+// MARK: - Out-of-scope shapes (must NOT fire SWIFT_NPE)
+
+// `try!` of a throwing call is an unhandled-error force-try, not a nil
+// dereference: it lowers to `swift_unexpectedError` on the `error != nil`
+// branch, a different shape from the Optional force-unwrap trap. Pins that the
+// recogniser leaves it alone -- it must not be miscategorised as SWIFT_NPE.
+enum ForceTryError: Error { case boom }
+
+@inline(never)
+func mayThrow(_ shouldThrow: Bool) throws -> Int {
+  if shouldThrow { throw ForceTryError.boom }
+  return 1
+}
+
+func tryForceUnwrap_noSwiftNPE() -> Int {
+  return try! mayThrow(true)
+}
+
+// `.map` / `.flatMap` on an Optional propagate the Optional without
+// force-unwrapping; `??` substitutes a default. None can trap, so none should
+// fire SWIFT_NPE.
+func optionalMap_good(_ x: Int?) -> Int? {
+  return x.map { $0 + 1 }
+}
+
+func optionalFlatMap_good(_ x: Int?) -> Int? {
+  return x.flatMap { Optional($0 + 1) }
+}
