Merge pull request #27235 from theblixguy/fix/SR-11381_5.1

[5.1] [PropertyWrappers] Fix a bug with property type being overwritten with wrong type

Author: DougGregor

lib/Sema/TypeCheckConstraints.cpp

@@ -2632,7 +2632,7 @@ bool TypeChecker::typeCheckBinding(Pattern *&pattern, Expr *&initializer,
                           emptyLocator);
         return propertyType;
       }
-      
+
       // Otherwise, compute the wrapped value type directly.
       return computeWrappedValueType(wrappedVar, initType);
     }
@@ -2654,10 +2654,10 @@ bool TypeChecker::typeCheckBinding(Pattern *&pattern, Expr *&initializer,
         // is the initialization of the property wrapper instance.
         initType = cs.getType(expr);
 
-        // Add a conversion constraint between the pattern type and the
+        // Add an equal constraint between the pattern type and the
         // property wrapper's "value" type.
-        cs.addConstraint(ConstraintKind::Conversion, patternType,
-                         getPatternInitType(&cs), Locator, /*isFavored*/true);
+        cs.addConstraint(ConstraintKind::Equal, patternType,
+                         getPatternInitType(&cs), Locator, /*isFavored*/ true);
       } else {
         // The initializer type is the type of the pattern.
         initType = patternType;

test/decl/var/property_wrappers.swift

@@ -1131,3 +1131,17 @@ struct UseNonMutatingProjectedValueSet {
     x = 42  // expected-error{{cannot assign to property: 'self' is immutable}}
   }
 }
+
+// SR-11381
+
+@propertyWrapper
+struct SR_11381_W<T> {
+  init(wrappedValue: T) {}
+  var wrappedValue: T {
+    fatalError()
+  }
+}
+
+struct SR_11381_S {
+  @SR_11381_W var foo: Int = nil // expected-error {{'nil' requires a contextual type}}
+}