[Parse] Set AttrRange for @nonisolated

Make sure we set the `AttrRange` in cases where `@` is present, but
`unsafe` isn't present.

rdar://147965036

Author: hamishknight

lib/Parse/ParseDecl.cpp

@@ -3741,6 +3741,7 @@ ParserStatus Parser::parseNewDeclAttribute(DeclAttributes &Attributes,
     break;
   }
   case DeclAttrKind::Nonisolated: {
+    AttrRange = Loc;
     std::optional<bool> isUnsafe(false);
     if (EnableParameterizedNonisolated) {
       isUnsafe =

test/Concurrency/nonisolated_rules.swift

@@ -166,3 +166,12 @@ final class KlassB: Sendable {
   // expected-error@+1 {{'nonisolated' cannot be applied to mutable stored properties}}
   nonisolated var test: Int = 1
 }
+
+// rdar://147965036 - Make sure we don't crash.
+func rdar147965036() {
+  func test(_: () -> Void) {}
+  test { @nonisolated in
+    // expected-error@-1 {{'nonisolated' is a declaration modifier, not an attribute}}
+    // expected-error@-2 {{'nonisolated' is not supported on a closure}}
+  }
+}