stdlib: make InlineArray work with the new vector_base_addr instruction

Don't unsafe-cast from the InlineArray struct itself, but from `_storage` which is the actual array buffer.
This also requires making `_storage` a var.

Author: eeckstein

stdlib/public/core/InlineArray.swift

@@ -46,7 +46,7 @@
 @_addressableForDependencies
 public struct InlineArray<let count: Int, Element: ~Copyable>: ~Copyable {
   @usableFromInline
-  internal let _storage: Builtin.FixedArray<count, Element>
+  internal var _storage: Builtin.FixedArray<count, Element>
 }
 
 @available(SwiftStdlib 6.2, *)
@@ -69,7 +69,7 @@ extension InlineArray where Element: ~Copyable {
   @_alwaysEmitIntoClient
   @_transparent
   internal var _address: UnsafePointer<Element> {
-    unsafe UnsafePointer<Element>(Builtin.unprotectedAddressOfBorrow(self))
+    unsafe UnsafePointer<Element>(Builtin.unprotectedAddressOfBorrow(_storage))
   }
 
   /// Returns a buffer pointer over the entire array.
@@ -86,7 +86,7 @@ extension InlineArray where Element: ~Copyable {
   @_transparent
   internal var _mutableAddress: UnsafeMutablePointer<Element> {
     mutating get {
-      unsafe UnsafeMutablePointer<Element>(Builtin.unprotectedAddressOf(&self))
+      unsafe UnsafeMutablePointer<Element>(Builtin.unprotectedAddressOf(&_storage))
     }
   }
 
@@ -147,7 +147,7 @@ extension InlineArray where Element: ~Copyable {
   @_alwaysEmitIntoClient
   public init<E: Error>(_ body: (Index) throws(E) -> Element) throws(E) {
 #if $BuiltinEmplaceTypedThrows
-    self = try Builtin.emplace { (rawPtr) throws(E) -> () in
+    _storage = try Builtin.emplace { (rawPtr) throws(E) -> () in
       let buffer = unsafe Self._initializationBuffer(start: rawPtr)
 
       for i in 0 ..< count {
@@ -204,7 +204,7 @@ extension InlineArray where Element: ~Copyable {
     //        and take the underlying value within the closure.
     var o: Element? = first
 
-    self = try Builtin.emplace { (rawPtr) throws(E) -> () in
+    _storage = try Builtin.emplace { (rawPtr) throws(E) -> () in
       let buffer = unsafe Self._initializationBuffer(start: rawPtr)
 
       guard Self.count > 0 else {
@@ -248,7 +248,7 @@ extension InlineArray where Element: Copyable {
   @_alwaysEmitIntoClient
   public init(repeating value: Element) {
 #if $ValueGenericsNameLookup
-    self = Builtin.emplace {
+    _storage = Builtin.emplace {
       let buffer = unsafe Self._initializationBuffer(start: $0)
 
       unsafe buffer.initialize(repeating: value)

test/abi/macOS/arm64/stdlib.swift

@@ -1122,3 +1122,8 @@ Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7Ra
 
 // Duration.nanoseconds(_:)
 Added: _$ss8DurationV11nanosecondsyABSdFZ
+
+// var InlineArray._storage
+Added: _$ss11InlineArrayVsRi__rlE8_storagexq_BVvM
+Added: _$ss11InlineArrayVsRi__rlE8_storagexq_BVvs
+

test/abi/macOS/x86_64/stdlib.swift

@@ -1123,3 +1123,8 @@ Added: $ld$previous$@rpath/libswiftCompatibilitySpan.dylib$$1$10.14$15.0$_$ss7Ra
 
 // Duration.nanoseconds(_:)
 Added: _$ss8DurationV11nanosecondsyABSdFZ
+
+// var InlineArray._storage
+Added: _$ss11InlineArrayVsRi__rlE8_storagexq_BVvM
+Added: _$ss11InlineArrayVsRi__rlE8_storagexq_BVvs
+