[IDE] Fix type reconstructions for PrivateDeclName.

Without this fix, the type reconstruction logic chokes on
demangled subtree of the kind:

kind=DeclContext
  kind=Function
    kind=Module, text="swift_ide_test"
    kind=PrivateDeclName
      kind=Identifier, text="_0830B395847924C73A6666B87EFD2ADF"
      kind=Identifier, text="patatino"

Fixes the compiler part of <rdar://problem/38248403>

Author: Davide Italiano

lib/IDE/TypeReconstruction.cpp

@@ -1157,6 +1157,40 @@ static bool CompareFunctionTypes(const AnyFunctionType *f,
   return (in_matches && out_matches);
 }
 
+static void VisitNodePrivateDeclName(
+    ASTContext *ast,
+    Demangle::NodePointer parent_node,
+    Demangle::NodePointer cur_node, VisitNodeResult &result) {
+  DeclKind decl_kind = GetKindAsDeclKind(parent_node->getKind());
+
+  if (cur_node->getNumChildren() != 2) {
+    if (result._error.empty())
+      result._error = stringWithFormat(
+          "unable to retrieve content for Node::Kind::PrivateDeclName");
+    return;
+  }
+
+  Demangle::NodePointer priv_decl_id_node(cur_node->getChild(0));
+  Demangle::NodePointer id_node(cur_node->getChild(1));
+
+  if (!priv_decl_id_node->hasText() || !id_node->hasText()) {
+    if (result._error.empty())
+      result._error = stringWithFormat(
+          "unable to retrieve content for Node::Kind::PrivateDeclName");
+    return;
+  }
+
+  if (!FindFirstNamedDeclWithKind(ast, ast->getIdentifier(id_node->getText()),
+                                  decl_kind, result,
+                                  priv_decl_id_node->getText().str())) {
+    if (result._error.empty())
+      result._error = stringWithFormat(
+          "unable to find Node::Kind::PrivateDeclName '%s' in '%s'",
+          id_node->getText().str().c_str(),
+          priv_decl_id_node->getText().str().c_str());
+  }
+}
+
 // VisitNodeFunction gets used for Function, Variable and Allocator:
 static void VisitNodeFunction(
     ASTContext *ast,
@@ -1191,6 +1225,25 @@ static void VisitNodeFunction(
       VisitNode(ast, *pos, decl_scope_result);
       break;
 
+    case Demangle::Node::Kind::PrivateDeclName: {
+      VisitNodePrivateDeclName(ast, cur_node, child, decl_scope_result);
+
+      // No results found, giving up.
+      if (decl_scope_result._decls.empty())
+        break;
+
+      std::copy(decl_scope_result._decls.begin(),
+                decl_scope_result._decls.end(),
+                back_inserter(identifier_result._decls));
+      std::copy(decl_scope_result._types.begin(),
+                decl_scope_result._types.end(),
+                back_inserter(identifier_result._types));
+      identifier_result._module = decl_scope_result._module;
+      if (decl_scope_result._decls.size() == 1)
+        found_univocous = true;
+      break;
+    }
+
     case Demangle::Node::Kind::LabelList: {
       for (const auto &label : **pos) {
         if (label->getKind() == Demangle::Node::Kind::FirstElementMarker)
@@ -1670,40 +1723,6 @@ static void VisitNodeLocalDeclName(
   }
 }
 
-static void VisitNodePrivateDeclName(
-    ASTContext *ast,
-    Demangle::NodePointer parent_node,
-    Demangle::NodePointer cur_node, VisitNodeResult &result) {
-  DeclKind decl_kind = GetKindAsDeclKind(parent_node->getKind());
-
-  if (cur_node->getNumChildren() != 2) {
-    if (result._error.empty())
-      result._error = stringWithFormat(
-          "unable to retrieve content for Node::Kind::PrivateDeclName");
-    return;
-  }
-
-  Demangle::NodePointer priv_decl_id_node(cur_node->getChild(0));
-  Demangle::NodePointer id_node(cur_node->getChild(1));
-
-  if (!priv_decl_id_node->hasText() || !id_node->hasText()) {
-    if (result._error.empty())
-      result._error = stringWithFormat(
-          "unable to retrieve content for Node::Kind::PrivateDeclName");
-    return;
-  }
-
-  if (!FindFirstNamedDeclWithKind(ast, ast->getIdentifier(id_node->getText()),
-                                  decl_kind, result,
-                                  priv_decl_id_node->getText().str())) {
-    if (result._error.empty())
-      result._error = stringWithFormat(
-          "unable to find Node::Kind::PrivateDeclName '%s' in '%s'",
-          id_node->getText().str().c_str(),
-          priv_decl_id_node->getText().str().c_str());
-  }
-}
-
 static void VisitNodeRelatedEntityDeclName(
     ASTContext *ast,
     Demangle::NodePointer parent_node,

test/IDE/reconstruct_type_from_mangled_name.swift

@@ -267,8 +267,7 @@ func hasLocalDecls() {
 
 fileprivate struct VeryPrivateData {}
 
-// FIXME
-// CHECK: decl: FAILURE for 'privateFunction'
+// CHECK: decl: fileprivate func privateFunction(_ d: VeryPrivateData) for 'privateFunction'
 fileprivate func privateFunction(_ d: VeryPrivateData) {}
 
 struct HasSubscript {
@@ -306,3 +305,12 @@ struct HasGenericSubscript<T> {
     set {}
   }
 }
+
+private
+// CHECK: decl: private func patatino<T>(_ vers1: T, _ vers2: T) -> Bool where T : Comparable for
+func patatino<T: Comparable>(_ vers1: T, _ vers2: T) -> Bool {
+  // CHECK: decl: FAILURE   for 'T' usr=s:14swift_ide_test8patatino33_D7B956AE2D93947DFA67A1ECF93EF238LLySbx_xts10ComparableRzlF1TL_xmfp decl
+  // CHECK: decl: let vers1: T      for 'vers1' usr=s:14swift_ide_test8patatino33_D7B956AE2D93947DFA67A1ECF93EF238LLySbx_xts10ComparableRzlF5vers1L_xvp
+  // CHECK: decl: let vers2: T      for 'vers2' usr=s:14swift_ide_test8patatino33_D7B956AE2D93947DFA67A1ECF93EF238LLySbx_xts10ComparableRzlF5vers2L_xvp
+  return vers1 < vers2;
+}