[AST] Use PatternBindingDecl::createImplicit in more places

And simplify the implementation of `create`.

Author: hamishknight

lib/AST/Decl.cpp

@@ -1882,27 +1882,18 @@ PatternBindingDecl::create(ASTContext &Ctx, SourceLoc StaticLoc,
                            StaticSpellingKind StaticSpelling, SourceLoc VarLoc,
                            Pattern *Pat, SourceLoc EqualLoc, Expr *E,
                            DeclContext *Parent) {
-  DeclContext *BindingInitContext = nullptr;
-  if (!Parent->isLocalContext())
-    BindingInitContext = new (Ctx) PatternBindingInitializer(Parent);
-
-  auto PBE = PatternBindingEntry(Pat, EqualLoc, E, BindingInitContext);
-  auto *Result = create(Ctx, StaticLoc, StaticSpelling, VarLoc, PBE, Parent);
-
-  if (BindingInitContext)
-    cast<PatternBindingInitializer>(BindingInitContext)->setBinding(Result, 0);
-
-  return Result;
+  // We can provide a null context, 'create' will fill it in for us.
+  // FIXME: This seems dubious, see the comment in 'create'.
+  auto PBE = PatternBindingEntry(Pat, EqualLoc, E, /*InitContext*/ nullptr);
+  return create(Ctx, StaticLoc, StaticSpelling, VarLoc, PBE, Parent);
 }
 
 PatternBindingDecl *PatternBindingDecl::createImplicit(
     ASTContext &Ctx, StaticSpellingKind StaticSpelling, Pattern *Pat, Expr *E,
     DeclContext *Parent, SourceLoc VarLoc) {
   auto *Result = create(Ctx, /*StaticLoc*/ SourceLoc(), StaticSpelling, VarLoc,
-                        Pat, /*EqualLoc*/ SourceLoc(), nullptr, Parent);
+                        Pat, /*EqualLoc*/ SourceLoc(), E, Parent);
   Result->setImplicit();
-  Result->setInit(0, E);
-  Result->setOriginalInit(0, E);
   return Result;
 }
 
@@ -1937,6 +1928,10 @@ PatternBindingDecl::create(ASTContext &Ctx, SourceLoc StaticLoc,
     auto &newEntry = entries[elt];
     newEntry = pe; // This should take care of initializer with flags
     DeclContext *initContext = pe.getInitContext();
+
+    // FIXME: We ought to reconsider this since it won't recontextualize any
+    // closures/decls present in the initialization expr. This currently should
+    // only affect implicit code though.
     if (!initContext && !Parent->isLocalContext()) {
       auto pbi = new (Ctx) PatternBindingInitializer(Parent);
       pbi->setBinding(PBD, elt);

lib/Sema/CSApply.cpp

@@ -1827,19 +1827,13 @@ namespace {
                                                  dc);
             capture->setImplicit();
             capture->setInterfaceType(base->getType()->mapTypeOutOfContext());
-            
-            NamedPattern *capturePat = new (context) NamedPattern(capture);
-            capturePat->setImplicit();
-            capturePat->setType(base->getType());
-            
-            auto capturePBE = PatternBindingEntry(capturePat,
-                                                  SourceLoc(), base, dc);
-            auto captureDecl = PatternBindingDecl::create(context, SourceLoc(),
-                                                          {}, SourceLoc(),
-                                                          capturePBE,
-                                                          dc);
-            captureDecl->setImplicit();
-            
+
+            auto *capturePat =
+                NamedPattern::createImplicit(context, capture, base->getType());
+
+            auto *captureDecl = PatternBindingDecl::createImplicit(
+                context, StaticSpellingKind::None, capturePat, base, dc);
+
             // Write the closure in terms of the capture.
             auto baseRef = new (context)
               DeclRefExpr(capture, DeclNameLoc(base->getLoc()), /*implicit*/ true);
@@ -5221,19 +5215,14 @@ namespace {
                                           dc);
       outerParam->setImplicit();
       outerParam->setInterfaceType(keyPathTy->mapTypeOutOfContext());
-      
-      NamedPattern *outerParamPat = new (ctx) NamedPattern(outerParam);
-      outerParamPat->setImplicit();
-      outerParamPat->setType(keyPathTy);
-      
-      auto outerParamPBE = PatternBindingEntry(outerParamPat,
-                                               SourceLoc(), E, dc);
+
+      auto *outerParamPat =
+          NamedPattern::createImplicit(ctx, outerParam, keyPathTy);
+
       solution.setExprTypes(E);
-      auto outerParamDecl = PatternBindingDecl::create(ctx, SourceLoc(),
-                                                       {}, SourceLoc(),
-                                                       outerParamPBE,
-                                                       dc);
-      outerParamDecl->setImplicit();
+      auto *outerParamDecl = PatternBindingDecl::createImplicit(
+          ctx, StaticSpellingKind::None, outerParamPat, E, dc);
+
       auto outerParamCapture = CaptureListEntry(outerParamDecl);
       auto captureExpr = CaptureListExpr::create(ctx, outerParamCapture,
                                                  closure);