[AST] Allow pattern bindings to be marked as fully verified

This would be used by closures because they handle patterns
and initializers via solver and set them back to the pattern
binding decl as fully type-checked.

Author: xedin

include/swift/AST/Decl.h

@@ -1805,7 +1805,12 @@ class PatternBindingDecl final : public Decl,
     return getPatternList()[i].getPattern();
   }
 
-  void setPattern(unsigned i, Pattern *Pat, DeclContext *InitContext);
+  void setPattern(unsigned i, Pattern *Pat, DeclContext *InitContext,
+                  bool isFullyValidated = false);
+
+  bool isFullyValidated(unsigned i) const {
+    return getPatternList()[i].isFullyValidated();
+  }
 
   DeclContext *getInitContext(unsigned i) const {
     return getPatternList()[i].getInitContext();

lib/AST/Decl.cpp

@@ -1658,18 +1658,23 @@ bool PatternBindingDecl::hasStorage() const {
 }
 
 void PatternBindingDecl::setPattern(unsigned i, Pattern *P,
-                                    DeclContext *InitContext) {
+                                    DeclContext *InitContext,
+                                    bool isFullyValidated) {
   auto PatternList = getMutablePatternList();
   PatternList[i].setPattern(P);
   PatternList[i].setInitContext(InitContext);
 
   // Make sure that any VarDecl's contained within the pattern know about this
   // PatternBindingDecl as their parent.
-  if (P)
+  if (P) {
     P->forEachVariable([&](VarDecl *VD) {
       if (!VD->isCaptureList())
         VD->setParentPatternBinding(this);
     });
+
+    if (isFullyValidated)
+      PatternList[i].setFullyValidated();
+  }
 }
 
 

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1880,8 +1880,11 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     auto &Ctx = getASTContext();
     for (auto i : range(PBD->getNumPatternEntries())) {
-      const auto *entry = evaluateOrDefault(
-          Ctx.evaluator, PatternBindingEntryRequest{PBD, i}, nullptr);
+      const auto *entry =
+          PBD->isFullyValidated(i)
+              ? &PBD->getPatternList()[i]
+              : evaluateOrDefault(Ctx.evaluator,
+                                  PatternBindingEntryRequest{PBD, i}, nullptr);
       assert(entry && "No pattern binding entry?");
 
       const auto *Pat = PBD->getPattern(i);