[ConstraintSystem] Allow SolutionApplicationTarget to store the

innermost call to init(wrappedValue:) if the target is for initialization
of a property wrapper's backing storage.

Author: hborla

lib/Sema/ConstraintSystem.cpp

@@ -4157,6 +4157,7 @@ SolutionApplicationTarget::SolutionApplicationTarget(
   expression.convertType = convertType;
   expression.pattern = nullptr;
   expression.wrappedVar = nullptr;
+  expression.innermostWrappedValueInit = nullptr;
   expression.isDiscarded = isDiscarded;
   expression.bindPatternVarsOneWay = false;
   expression.patternBinding = nullptr;

lib/Sema/ConstraintSystem.h

@@ -1202,6 +1202,10 @@ class SolutionApplicationTarget {
       /// this is an initialization involving a property wrapper.
       VarDecl *wrappedVar;
 
+      /// The innermost call to \c init(wrappedValue:), if this is an
+      /// initialization involving a property wrapper.
+      ApplyExpr *innermostWrappedValueInit;
+
       /// Whether the expression result will be discarded at the end.
       bool isDiscarded;
 
@@ -1384,6 +1388,20 @@ class SolutionApplicationTarget {
         expression.bindPatternVarsOneWay;
   }
 
+  /// Whether or not an opaque value placeholder should be injected into the
+  /// first \c wrappedValue argument of an apply expression.
+  bool shouldInjectWrappedValuePlaceholder(ApplyExpr *apply) const {
+    if (kind != Kind::expression ||
+        expression.contextualPurpose != CTP_Initialization)
+      return false;
+
+    auto *wrappedVar = expression.wrappedVar;
+    if (!wrappedVar || wrappedVar->isStatic())
+      return false;
+
+    return expression.innermostWrappedValueInit == apply;
+  }
+
   /// Retrieve the wrapped variable when initializing a pattern with a
   /// property wrapper.
   VarDecl *getInitializationWrappedVar() const {