[NFC] Update tests and diagnostics

test/ModuleInterface/Inputs/lifetime_underscored_dependence.swift

@@ -0,0 +1,79 @@
+public struct AnotherView : ~Escapable {
+  @usableFromInline let _ptr: UnsafeRawBufferPointer
+  @usableFromInline let _count: Int
+  @_lifetime(borrow ptr)
+  internal init(_ ptr: UnsafeRawBufferPointer, _ count: Int) {
+    self._ptr = ptr
+    self._count = count
+  }
+}
+
+public struct BufferView : ~Escapable {
+  @usableFromInline let _ptr: UnsafeRawBufferPointer
+  @usableFromInline let _count: Int
+  @usableFromInline 
+  @_lifetime(borrow ptr)
+  internal init(_ ptr: UnsafeRawBufferPointer, _ count: Int) {
+    self._ptr = ptr
+    self._count = count
+  }
+
+  @inlinable
+  @_lifetime(borrow a)
+  internal init(_ ptr: UnsafeRawBufferPointer, _ a: borrowing Array<Int>) {
+    let bv = BufferView(ptr, a.count)
+    self = _overrideLifetime(bv, borrowing: a)
+  }
+  @inlinable
+  @_lifetime(copy a)
+  internal init(_ ptr: UnsafeRawBufferPointer, _ a: consuming AnotherView) {
+    let bv = BufferView(ptr, a._count)
+    self = _overrideLifetime(bv, copying: a)
+  }
+}
+
+@inlinable
+@_lifetime(copy x)
+public func derive(_ x: consuming BufferView) -> BufferView {
+  let pointer = x._ptr
+  let bv = BufferView(pointer, x._count)
+  return _overrideLifetime(bv, copying: x)
+}
+
+@inlinable
+public func use(_ x: consuming BufferView) {}
+
+@inlinable
+@_lifetime(copy view)
+public func consumeAndCreate(_ view: consuming BufferView) -> BufferView {
+  let pointer = view._ptr
+  let bv = BufferView(pointer, view._count)
+  return _overrideLifetime(bv, copying: view)
+}
+
+// FIXME: Filed rdar://150398673 ([nonescapable] allocbox-to-stack fails causing lifetime diagnostics to fail)
+// Remove _overrideLifetime when this is fixed.
+@inlinable
+@_lifetime(copy this, copy that)
+public func deriveThisOrThat(_ this: consuming BufferView, _ that: consuming BufferView) -> BufferView {
+  if (Int.random(in: 1..<100) == 0) {
+    let thisView = BufferView(this._ptr, this._count)
+    return _overrideLifetime(thisView, copying: this)
+  }
+  let thatView = BufferView(that._ptr, that._count)
+  return _overrideLifetime(thatView, copying: that)
+}
+
+public struct Container {
+  var buffer: UnsafeRawBufferPointer
+  var object: AnyObject
+}
+
+extension Container {
+  public var storage: BufferView {
+    get {
+      let view = BufferView(buffer, 1)
+      return _overrideLifetime(view, borrowing: self)
+    }
+  }
+}

test/ModuleInterface/lifetime_underscored_dependence_test.swift

@@ -0,0 +1,112 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -swift-version 5 -enable-library-evolution -emit-module \
+// RUN:     -enable-experimental-feature Lifetimes \
+// RUN:     -enable-experimental-feature Lifetimes \
+// RUN:     -o %t/lifetime_underscored_dependence.swiftmodule \
+// RUN:     -emit-module-interface-path %t/lifetime_underscored_dependence.swiftinterface \
+// RUN:     %S/Inputs/lifetime_underscored_dependence.swift
+
+// Check the interfaces
+
+// RUN: %FileCheck %s < %t/lifetime_underscored_dependence.swiftinterface
+
+// See if we can compile a module through just the interface and typecheck using it.
+
+// RUN: %target-swift-frontend -compile-module-from-interface \
+// RUN:    -enable-experimental-feature Lifetimes \
+// RUN:    %t/lifetime_underscored_dependence.swiftinterface -o %t/lifetime_underscored_dependence.swiftmodule
+
+// RUN: %target-swift-frontend -typecheck -I %t %s \
+// RUN:    -enable-experimental-feature Lifetimes
+
+// REQUIRES: swift_feature_Lifetimes
+
+import lifetime_underscored_dependence
+// CHECK:  #if compiler(>=5.3) && $Lifetimes
+// CHECK:  @_lifetime(borrow a)
+// CHECK:  @inlinable internal init(_ ptr: Swift.UnsafeRawBufferPointer, _ a: borrowing Swift.Array<Swift.Int>) {
+// CHECK:    let bv = BufferView(ptr, a.count)
+// CHECK:    self = _overrideLifetime(bv, borrowing: a)
+// CHECK:  }
+// CHECK:  #else
+// CHECK:  @lifetime(borrow a)
+// CHECK:  @inlinable internal init(_ ptr: Swift.UnsafeRawBufferPointer, _ a: borrowing Swift.Array<Swift.Int>) {
+// CHECK:    let bv = BufferView(ptr, a.count)
+// CHECK:    self = _overrideLifetime(bv, borrowing: a)
+// CHECK:  }
+// CHECK:  #endif
+
+// CHECK:  #if compiler(>=5.3) && $Lifetimes
+// CHECK:  @_lifetime(copy a)
+// CHECK:  @inlinable internal init(_ ptr: Swift.UnsafeRawBufferPointer, _ a: consuming lifetime_underscored_dependence.AnotherView) {
+// CHECK:    let bv = BufferView(ptr, a._count)
+// CHECK:    self = _overrideLifetime(bv, copying: a)
+// CHECK:  }
+// CHECK:  #else
+// CHECK:  @lifetime(copy a)
+// CHECK:  @inlinable internal init(_ ptr: Swift.UnsafeRawBufferPointer, _ a: consuming lifetime_underscored_dependence.AnotherView) {
+// CHECK:    let bv = BufferView(ptr, a._count)
+// CHECK:    self = _overrideLifetime(bv, copying: a)
+// CHECK:  }
+// CHECK:  #endif
+
+// CHECK:#if compiler(>=5.3) && $Lifetimes
+// CHECK:@_lifetime(copy x)
+// CHECK:@inlinable public func derive(_ x: consuming lifetime_underscored_dependence.BufferView) -> lifetime_underscored_dependence.BufferView {
+// CHECK:  let pointer = x._ptr
+// CHECK:  let bv = BufferView(pointer, x._count)
+// CHECK:  return _overrideLifetime(bv, copying: x)
+// CHECK:}
+// CHECK:#else
+// CHECK:@lifetime(copy x)
+// CHECK:@inlinable public func derive(_ x: consuming lifetime_underscored_dependence.BufferView) -> lifetime_underscored_dependence.BufferView {
+// CHECK:  let pointer = x._ptr
+// CHECK:  let bv = BufferView(pointer, x._count)
+// CHECK:  return _overrideLifetime(bv, copying: x)
+// CHECK:}
+// CHECK:#endif
+
+// CHECK:#if compiler(>=5.3) && $Lifetimes
+// CHECK:@_lifetime(copy view)
+// CHECK:@inlinable public func consumeAndCreate(_ view: consuming lifetime_underscored_dependence.BufferView) -> lifetime_underscored_dependence.BufferView {
+// CHECK:  let pointer = view._ptr
+// CHECK:  let bv = BufferView(pointer, view._count)
+// CHECK:  return _overrideLifetime(bv, copying: view)
+// CHECK:}
+// CHECK:#else
+// CHECK:@lifetime(copy view)
+// CHECK:@inlinable public func consumeAndCreate(_ view: consuming lifetime_underscored_dependence.BufferView) -> lifetime_underscored_dependence.BufferView {
+// CHECK:  let pointer = view._ptr
+// CHECK:  let bv = BufferView(pointer, view._count)
+// CHECK:  return _overrideLifetime(bv, copying: view)
+// CHECK:}
+// CHECK:#endif
+
+// CHECK:#if compiler(>=5.3) && $Lifetimes
+// CHECK:@_lifetime(copy this, copy that)
+// CHECK:@inlinable public func deriveThisOrThat(_ this: consuming lifetime_underscored_dependence.BufferView, _ that: consuming lifetime_underscored_dependence.BufferView) -> lifetime_underscored_dependence.BufferView {
+// CHECK:  if (Int.random(in: 1..<100) == 0) {
+// CHECK:    let thisView = BufferView(this._ptr, this._count)
+// CHECK:    return _overrideLifetime(thisView, copying: this)
+// CHECK:  }
+// CHECK:  let thatView = BufferView(that._ptr, that._count)
+// CHECK:  return _overrideLifetime(thatView, copying: that)
+// CHECK:}
+// CHECK:#else
+// CHECK:@lifetime(copy this, copy that)
+// CHECK:@inlinable public func deriveThisOrThat(_ this: consuming lifetime_underscored_dependence.BufferView, _ that: consuming lifetime_underscored_dependence.BufferView) -> lifetime_underscored_dependence.BufferView {
+// CHECK:  if (Int.random(in: 1..<100) == 0) {
+// CHECK:    let thisView = BufferView(this._ptr, this._count)
+// CHECK:    return _overrideLifetime(thisView, copying: this)
+// CHECK:  }
+// CHECK:  let thatView = BufferView(that._ptr, that._count)
+// CHECK:  return _overrideLifetime(thatView, copying: that)
+// CHECK:}
+// CHECK:#endif
+
+// Check that an implicitly dependent variable accessor is guarded by LifetimeDependence.
+//
+// CHECK: extension lifetime_underscored_dependence.Container {
+// CHECK-NEXT: #if compiler(>=5.3) && $NonescapableTypes && $LifetimeDependence
+// CHECK-NEXT:   public var storage: lifetime_underscored_dependence.BufferView {