Merge pull request #18260 from rudkx/add-test-for-sr6299

Author: swift-ci

test/decl/func/rethrows.swift

@@ -551,3 +551,36 @@ public func variadic_rethrows(_ values: Int..., body: (Int) throws -> ()) rethro
 public func rdar40472018() {
   variadic_rethrows(1, 2) { _ in }
 }
+
+
+// https://bugs.swift.org/browse/SR-6299
+// Verify that we do not emit an invalid
+//   "... can throw but the expression is not marked with 'try'"
+// error on the use of the operators.
+
+infix operator <|: infixr0
+infix operator |>: infixl1
+
+precedencegroup infixr0 {
+  associativity: right
+}
+precedencegroup infixl1 {
+  associativity: left
+  higherThan: infixr0
+}
+
+func <| <A, B> (f: (A) throws -> B, a: A) rethrows -> B {
+  return try f(a)
+}
+func |> <A, B> (a: A, f: (A) -> B) -> B {
+  return try f(a) // expected-warning {{no calls to throwing functions occur within 'try' expression}}
+}
+
+struct Box<A> {
+  let unbox: A
+}
+func suchThat<A>(_ x: Box<A>) -> (@escaping (A) -> A) -> Box<A> {
+  return { f in Box(unbox: f(x.unbox)) }
+}
+
+Box(unbox: 1) |> suchThat <| { $0 + 1 } // expected-warning {{result of operator '<|' is unused}}