[Property Wrappers] Allow property wrappers on local variables.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -5202,8 +5202,6 @@ ERROR(property_wrapper_mutating_get_composed_to_get_only,none,
       "property wrapper %0 with a mutating getter cannot be composed inside "
       "get-only property wrapper %1", (TypeLoc, TypeLoc))
 
-ERROR(property_wrapper_local,none,
-      "property wrappers are not yet supported on local properties", ())
 ERROR(property_wrapper_top_level,none,
       "property wrappers are not yet supported in top-level code", ())
 ERROR(property_wrapper_let, none,

lib/Sema/TypeCheckPropertyWrapper.cpp

@@ -414,12 +414,6 @@ AttachedPropertyWrappersRequest::evaluate(Evaluator &evaluator,
     // Check various restrictions on which properties can have wrappers
     // attached to them.
 
-    // Local properties do not yet support wrappers.
-    if (var->getDeclContext()->isLocalContext()) {
-      ctx.Diags.diagnose(attr->getLocation(), diag::property_wrapper_local);
-      continue;
-    }
-
     // Nor does top-level code.
     if (var->getDeclContext()->isModuleScopeContext()) {
       ctx.Diags.diagnose(attr->getLocation(), diag::property_wrapper_top_level);

test/decl/var/property_wrappers.swift

@@ -140,16 +140,39 @@ struct _UppercaseWrapper<T> {
 }
 
 // ---------------------------------------------------------------------------
-// Limitations on where property wrappers can be used
+// Local property wrappers
 // ---------------------------------------------------------------------------
 
 func testLocalContext() {
-  @WrapperWithInitialValue // expected-error{{property wrappers are not yet supported on local properties}}
+  @WrapperWithInitialValue
   var x = 17
   x = 42
-  _ = x
+  let _: Int = x
+  let _: WrapperWithInitialValue = _x
+
+  @WrapperWithInitialValue(wrappedValue: 17)
+  var initialValue
+  let _: Int = initialValue
+  let _: WrapperWithInitialValue = _initialValue
+
+  @Clamping(min: 0, max: 100)
+  var percent = 50
+  let _: Int = percent
+  let _: Clamping = _percent
+
+  @WrapperA @WrapperB
+  var composed = "hello"
+  let _: WrapperA<WrapperB> = _composed
+
+  @WrapperWithStorageRef
+  var hasProjection = 10
+  let _: Wrapper = $hasProjection
 }
 
+// ---------------------------------------------------------------------------
+// Limitations on where property wrappers can be used
+// ---------------------------------------------------------------------------
+
 enum SomeEnum {
   case foo