AST: Factor out GenericParamList::configureGenericParamDepth()

Author: slavapestov

include/swift/AST/Decl.h

@@ -1422,13 +1422,10 @@ class GenericParamList final :
                        Requirements.back().getSourceRange().End);
   }
 
-  /// Retrieve the depth of this generic parameter list.
-  unsigned getDepth() const {
-    unsigned depth = 0;
-    for (auto gp = getOuterParameters(); gp; gp = gp->getOuterParameters())
-      ++depth;
-    return depth;
-  }
+  unsigned getDepth() const;
+
+  /// Configure the depth of the generic parameters in this list.
+  void configureGenericParamDepth();
 
   /// Create a copy of the generic parameter list and all of its generic
   /// parameter declarations. The copied generic parameters are re-parented

lib/AST/Decl.cpp

@@ -687,6 +687,21 @@ void GenericParamList::addTrailingWhereClause(
   Requirements = newRequirements;
 }
 
+unsigned GenericParamList::getDepth() const {
+  unsigned depth = 0;
+  for (auto gpList = getOuterParameters();
+       gpList != nullptr;
+       gpList = gpList->getOuterParameters())
+    ++depth;
+  return depth;
+}
+
+void GenericParamList::configureGenericParamDepth() {
+  unsigned depth = getDepth();
+  for (auto param : *this)
+    param->setDepth(depth);
+}
+
 TrailingWhereClause::TrailingWhereClause(
                        SourceLoc whereLoc,
                        ArrayRef<RequirementRepr> requirements)

lib/Sema/TypeCheckGeneric.cpp

@@ -147,11 +147,9 @@ TypeChecker::gatherGenericParamBindingsText(
 void
 TypeChecker::prepareGenericParamList(GenericParamList *gp,
                                      DeclContext *dc) {
-  unsigned depth = gp->getDepth();
-  for (auto paramDecl : *gp) {
+  gp->configureGenericParamDepth();
+  for (auto paramDecl : *gp)
     checkDeclAttributesEarly(paramDecl);
-    paramDecl->setDepth(depth);
-  }
 }
 
 /// Add the generic parameter types from the given list to the vector.

lib/Sema/TypeChecker.cpp

@@ -285,21 +285,6 @@ static GenericParamList *cloneGenericParams(ASTContext &ctx,
   return toParams;
 }
 
-/// FIXME: Similar to TypeChecker::prepareGenericParamList(), which needs
-/// to be separated from the type checker.
-static void prepareGenericParamList(GenericParamList *genericParams) {
-  unsigned depth = genericParams->getDepth();
-  for (auto gp : *genericParams) {
-    if (gp->getDepth() == depth)
-      return;
-
-    gp->setDepth(depth);
-  }
-
-  if (auto outerGenericParams = genericParams->getOuterParameters())
-    prepareGenericParamList(outerGenericParams);
-}
-
 /// Ensure that the outer generic parameters of the given generic
 /// context have been configured.
 static void configureOuterGenericParams(const GenericContext *dc) {
@@ -353,9 +338,12 @@ static void bindExtensionToNominal(ExtensionDecl *ext,
         cloneGenericParams(ext->getASTContext(), ext, genericParams));
   }
 
+  // Set the depth of every generic parameter.
   auto *genericParams = ext->getGenericParams();
-  if (genericParams)
-    prepareGenericParamList(genericParams);
+  for (auto *outerParams = genericParams;
+       outerParams != nullptr;
+       outerParams = outerParams->getOuterParameters())
+    outerParams->configureGenericParamDepth();
 
   // If we have a trailing where clause, deal with it now.
   // For now, trailing where clauses are only permitted on protocol extensions.