From fcb69334e15e32049a45ebdcc7d2988acf441f5e Mon Sep 17 00:00:00 2001
From: "A. Jesse Jiryu Davis" <jesse@mongodb.com>
Date: Tue, 9 Feb 2021 15:06:07 -0500
Subject: SERVER-52542 Convert dropIndexes to IDL

---
 src/mongo/db/commands.h | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

(limited to 'src/mongo/db/commands.h')

diff --git a/src/mongo/db/commands.h b/src/mongo/db/commands.h
index 2d3df2eb106..813c5397ab2 100644
--- a/src/mongo/db/commands.h
+++ b/src/mongo/db/commands.h
@@ -930,6 +930,23 @@ public:
     }
 };
 
+namespace {
+// Used in BasicCommandWithRequestParser below.
+template <typename T, typename = int>
+struct CommandAlias {
+    // An empty alias is equivalent to no alias, see CommandRegistry::registerCommand.
+    static constexpr StringData kAlias = ""_sd;
+};
+
+template <typename T>
+struct CommandAlias<T, decltype((void)T::kCommandAlias, 0)> {
+    static constexpr StringData kAlias = T::kCommandAlias;
+};
+
+template <typename T>
+constexpr StringData command_alias_v = CommandAlias<T>::kAlias;
+}  // namespace
+
 /**
  * A CRTP base class for BasicCommandWithRequestParser, which simplifies writing commands that
  * accept requests generated by IDL to enforce API versioning and to overcome the complexity
@@ -952,7 +969,8 @@ public:
  *
  *      which enables it to be parsed as an IDL command.
  *
- *      - a 'constexpr StringData kCommandName' member.
+ *      - a 'static constexpr StringData kCommandName' member.
+ *      - (optional) a 'static constexpr StringData kCommandAlias' member.
  *
  *   - validateResult: that has a custom logic to validate the result BSON object
  *     to enforce API versioning.
@@ -961,9 +979,9 @@ public:
 template <typename Derived>
 class BasicCommandWithRequestParser : public BasicCommandWithReplyBuilderInterface {
 protected:
-    // Commands that only have a single name don't need to define any constructors.
     BasicCommandWithRequestParser()
-        : BasicCommandWithReplyBuilderInterface(Derived::Request::kCommandName) {}
+        : BasicCommandWithReplyBuilderInterface(Derived::Request::kCommandName,
+                                                command_alias_v<typename Derived::Request>) {}
 
     bool runWithReplyBuilder(OperationContext* opCtx,
                              const std::string& db,
@@ -1003,7 +1021,7 @@ protected:
         auto wcStatus = getWriteConcernStatusFromCommandResult(resultObj);
         if (!wcStatus.isOK()) {
             if (wcStatus.code() == ErrorCodes::TypeMismatch) {
-                // Result has "writeConcerError" field but it is not valid wce object.
+                // Result has "writeConcernError" field but it is not valid wce object.
                 uassertStatusOK(wcStatus);
             }
         }
-- 
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