[CS] Set property wrapper auxiliary var types in constraint generation

Rather than computing these each time we need to solve an element that
has a reference to them, let's just set them up-front when we generate
constraints for the corresponding variable.

Author: hamishknight

lib/Sema/CSSyntacticElement.cpp

@@ -141,36 +141,6 @@ class TypeVariableRefFinder : public ASTWalker {
       if (!var)
         return Action::Continue(expr);
 
-      if (auto *wrappedVar = var->getOriginalWrappedProperty()) {
-        // If there is no type it means that the body of the
-        // closure hasn't been resolved yet, so we can
-        // just skip it and wait for \c applyPropertyWrapperToParameter
-        // to assign types.
-        if (wrappedVar->hasImplicitPropertyWrapper())
-          return Action::Continue(expr);
-
-        auto outermostWrapperAttr =
-            wrappedVar->getOutermostAttachedPropertyWrapper();
-
-        // If the attribute doesn't have a type it could only mean
-        // that the declaration was incorrect.
-        if (!CS.hasType(outermostWrapperAttr->getTypeExpr()))
-          return Action::Continue(expr);
-
-        auto wrapperType =
-            CS.simplifyType(CS.getType(outermostWrapperAttr->getTypeExpr()));
-
-        if (var->getName().hasDollarPrefix()) {
-          // $<name> is the projected value var
-          CS.setType(var, computeProjectedValueType(wrappedVar, wrapperType));
-        } else {
-          // _<name> is the wrapper var
-          CS.setType(var, wrapperType);
-        }
-
-        return Action::Continue(expr);
-      }
-
       // If there is no type recorded yet, let's check whether
       // it is a placeholder variable implicitly generated by the
       // compiler.
@@ -817,6 +787,26 @@ class SyntacticElementConstraintGenerator
                                                        patternType);
   }
 
+  void setPropertyWrapperAuxiliaryTypes(const SyntacticElementTarget &target) {
+    if (!target.isForInitialization())
+      return;
+
+    auto *wrappedVar = target.getInitializationWrappedVar();
+    if (!wrappedVar)
+      return;
+
+    auto *outermostAttr = wrappedVar->getOutermostAttachedPropertyWrapper();
+    auto *wrapperTypeExpr = outermostAttr->getTypeExpr();
+
+    auto wrapperTy = cs.simplifyType(cs.getType(wrapperTypeExpr));
+    if (auto *projectedVal = wrappedVar->getPropertyWrapperProjectionVar()) {
+      auto projectedTy = computeProjectedValueType(wrappedVar, wrapperTy);
+      cs.setType(projectedVal, projectedTy);
+    }
+    if (auto *backing = wrappedVar->getPropertyWrapperBackingProperty())
+      cs.setType(backing, wrapperTy);
+  }
+
   void visitPatternBindingElement(PatternBindingDecl *patternBinding) {
     assert(locator->isLastElement<LocatorPathElt::PatternBindingElement>());
 
@@ -847,6 +837,9 @@ class SyntacticElementConstraintGenerator
       hadError = true;
       return;
     }
+
+    // Set the types of any auxiliary property wrapper vars.
+    setPropertyWrapperAuxiliaryTypes(*target);
   }
 
   void visitDecl(Decl *decl) {