[SR-15151] @discardableResult not propagated through return value / continuation

[stephencelis]

Previous ID	SR-15151
Radar	rdar://problem/82877277
Original Reporter	@stephencelis
Type	Bug

Environment

Swift 5.5

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, DiagnosticsQoI, TypeChecker
Assignee	None
Priority	Medium

md5: e80ffb61f8bb865977bd306915574028

Issue Description:

Not sure if it's practical to fix, but the following example produces an unused return value warning.

class MyViewModel: ObservableObject {
  @Published var array = ["A", "B", "C"]

  func removeFirst() {
    // warning: Result of call to 'withAnimation' is unused
    withAnimation {
      self.array.removeFirst()
    }
  }
}

Worse, when result builders are involved we get an error:

struct MyView: View {
  @State var array = ["A", "B", "C"]

  // error: Failed to produce diagnostic for expression
  var body: some View {
    Button("Remove first") {
      withAnimation {
        self.array.removeFirst()
      }
    }
  }
}

[typesanitizer]

It looks like JIRA botched the code example, could you please fix it? I tried fixing it locally but I hit a confusing error for which I've filed https://bugs.swift.org/browse/SR-15153

[stephencelis]

theindigamer (JIRA User) Updated! The view builder one actually errors, but I introduced a second code block showing the warning.

[typesanitizer]

@swift-ci create

[dfeinzimer]

Is this related to #60276? We're still seeing the warning in the Xcode 14.0 (14A309) release.

[stephencelis]

@dfeinzimer No this is a different issue / feature request.