CompatibilitySpan: Add MutableRawSpan.swift, MutableSpan.swift

Author: slavapestov

stdlib/public/core/Span/MutableRawSpan.swift

@@ -10,6 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if SPAN_COMPATIBILITY_STUB
+import Swift
+#endif
+
 // A MutableRawSpan represents a span of memory which
 // contains initialized `Element` instances.
 @safe
@@ -338,6 +342,10 @@ extension MutableRawSpan {
   }
 }
 
+// FIXME: The functions in this extension crash the SIL optimizer when built inside
+// the stub. But these declarations don't generate a public symbol anyway.
+#if !SPAN_COMPATIBILITY_STUB
+
 //MARK: copyMemory
 @available(SwiftStdlib 6.2, *)
 extension MutableRawSpan {
@@ -429,6 +437,7 @@ extension MutableRawSpan {
     update(fromContentsOf: source.bytes)
   }
 }
+#endif
 
 // MARK: sub-spans
 @available(SwiftStdlib 6.2, *)

stdlib/public/core/Span/MutableSpan.swift

@@ -10,6 +10,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if SPAN_COMPATIBILITY_STUB
+import Swift
+#endif
+
 // A MutableSpan<Element> represents a span of memory which
 // contains initialized `Element` instances.
 @safe

stdlib/toolchain/CompatibilitySpan/CMakeLists.txt

@@ -4,6 +4,8 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Darwin" AND DEFINED SWIFT_STDLIB_LIBRARY_BUILD_TY
 
   add_swift_target_library("${library_name}" ${SWIFT_STDLIB_LIBRARY_BUILD_TYPES} IS_STDLIB
     FakeStdlib.swift
+    ../../public/core/Span/MutableRawSpan.swift
+    ../../public/core/Span/MutableSpan.swift
     ../../public/core/Span/RawSpan.swift
     ../../public/core/Span/Span.swift
 

stdlib/toolchain/CompatibilitySpan/FakeStdlib.swift

@@ -59,6 +59,20 @@ internal func _overrideLifetime<
   dependent
 }
 
+@unsafe
+@_unsafeNonescapableResult
+@_alwaysEmitIntoClient
+@_transparent
+@lifetime(&source)
+internal func _overrideLifetime<
+  T: ~Copyable & ~Escapable, U: ~Copyable & ~Escapable
+>(
+  _ dependent: consuming T,
+  mutating source: inout U
+) -> T {
+  dependent
+}
+
 extension Range {
     @_alwaysEmitIntoClient
 	internal init(_uncheckedBounds bounds: (lower: Bound, upper: Bound)) {