[Parse] Avoid re-using attribute context for non-first entry

This could result in us changing the binding
index after-the-fact.

Author: hamishknight

lib/Parse/ParseDecl.cpp

@@ -8315,9 +8315,10 @@ Parser::parseDeclVar(ParseDeclOptions Flags,
       }
     });
 
-    // Check whether we have already established an initializer context.
+    // Check whether we have already established an initializer context for
+    // the first binding entry (subsequent entries need a separate context).
     PatternBindingInitializer *initContext =
-      findAttributeInitContent(Attributes);
+      PBDEntries.empty() ? findAttributeInitContent(Attributes) : nullptr;
 
     // Remember this pattern/init pair for our ultimate PatternBindingDecl. The
     // Initializer will be added later when/if it is parsed.

test/decl/var/property_wrappers.swift

@@ -253,6 +253,9 @@ struct MultipleWrappers {
 
   @WrapperWithInitialValue // expected-error 2{{property wrapper can only apply to a single variable}}
   var (y, z) = (1, 2)
+
+  @Clamping(min: 0, max: 255) // expected-error 2{{property wrapper can only apply to a single variable}}
+  var a = 0, b = 0
 }
 
 // ---------------------------------------------------------------------------