leftover-from-wildcard-projection-attempt.patch

diff --git a/src/mongo/db/commands/create_indexes.cpp b/src/mongo/db/commands/create_indexes.cpp
index b865dab3ab..f3219fef1d 100644
--- a/src/mongo/db/commands/create_indexes.cpp
+++ b/src/mongo/db/commands/create_indexes.cpp
@@ -637,6 +637,8 @@ std::unique_ptr<CreateIndexesCommand> makeTimeseriesCreateIndexesCommand(
     for (const auto& origIndex : origIndexes) {
         BSONObjBuilder builder;
         for (const auto& elem : origIndex) {
+            // Translates the time-series index spec, present in the 'key' field, to an index spec
+            // on the underlying buckets collection.
             if (elem.fieldNameStringData() == NewIndexSpec::kKeyFieldName) {
                 auto bucketsIndexSpecWithStatus =
                     timeseries::createBucketsIndexSpecFromTimeseriesIndexSpec(*timeseriesOptions,
@@ -650,6 +652,22 @@ std::unique_ptr<CreateIndexesCommand> makeTimeseriesCreateIndexesCommand(
                                std::move(bucketsIndexSpecWithStatus.getValue()));
                 continue;
             }
+
+            // Translates the 'wildcardProjection' field's time-series index paths to paths on the
+            // underlying buckets collection.
+            if (elem.fieldNameStringData() == NewIndexSpec::kWildcardProjectionFieldName) {
+                auto bucketsWildcardWithStatus =
+                    timeseries::createMetaFieldOnlyBucketsIndexSpec(*timeseriesOptions, elem.Obj());
+                uassert(ErrorCodes::CannotCreateIndex,
+                        str::stream() << bucketsWildcardWithStatus.getStatus().toString()
+                                      << " Command request: " << redact(origCmd.toBSON({})),
+                        bucketsWildcardWithStatus.isOK());
+
+                builder.append(NewIndexSpec::kWildcardProjectionFieldName,
+                               std::move(bucketsWildcardWithStatus.getValue()));
+                continue;
+            }
+
             builder.append(elem);
         }
         indexes.push_back(builder.obj());
diff --git a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
index aad973cf78..ad832773eb 100644
--- a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
+++ b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.cpp
@@ -27,18 +27,53 @@
  *    it in the license file.
  */
+#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kStorage
+
 #include "mongo/platform/basic.h"

 #include "mongo/db/timeseries/timeseries_index_schema_conversion_functions.h"

 #include "mongo/db/timeseries/timeseries_field_names.h"
 #include "mongo/db/timeseries/timeseries_gen.h"
+#include "mongo/logv2/log.h"
 #include "mongo/logv2/redaction.h"

 namespace mongo {

 namespace timeseries {

+StatusWith<BSONObj> createMetaFieldOnlyBucketsIndexSpec(const TimeseriesOptions& timeseriesOptions,
+                                                        const BSONObj& timeseriesIndexSpecBSON) {
+    auto metaField = timeseriesOptions.getMetaField();
+
+    BSONObjBuilder builder;
+    for (const auto& elem : timeseriesIndexSpecBSON) {
+        if (elem.fieldNameStringData() == *metaField) {
+            // The time-series 'metaField' field name always maps to a field named
+            // timeseries::kBucketMetaFieldName on the underlying buckets collection.
+            builder.appendAs(elem, timeseries::kBucketMetaFieldName);
+            continue;
+        }
+
+        // Lastly, time-series indexes on sub-documents of the 'metaField' are allowed.
+        if (elem.fieldNameStringData().startsWith(*metaField + ".")) {
+            builder.appendAs(elem,
+                             str::stream()
+                                 << timeseries::kBucketMetaFieldName << "."
+                                 << elem.fieldNameStringData().substr(metaField->size() + 1));
+            continue;
+        }
+
+        return {ErrorCodes::BadValue,
+                str::stream() << "Invalid index spec for time-series collection: "
+                              << redact(timeseriesIndexSpecBSON)
+                              << ", wildcardProjection is only allowed on the '" << *metaField
+                              << "'. field."};
+    }
+
+    return builder.obj();
+}
+
 StatusWith<BSONObj> createBucketsIndexSpecFromTimeseriesIndexSpec(
     const TimeseriesOptions& timeseriesOptions, const BSONObj& timeseriesIndexSpecBSON) {
     auto timeField = timeseriesOptions.getTimeField();
diff --git a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h
index 4fbb9c6139..16c01df5b5 100644
--- a/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h
+++ b/src/mongo/db/timeseries/timeseries_index_schema_conversion_functions.h
@@ -43,6 +43,14 @@ class TimeseriesOptions;
  */
 namespace timeseries {

+/**
+ * Creates a buckets collection spec from the 'timeseriesIndexSpecBSON' spec provided. Expects specs
+ * to only be on the 'metaField' field, or subfields thereof, specified in the provided
+ * 'timeseriesOptions'.
+ */
+StatusWith<BSONObj> createMetaFieldOnlyBucketsIndexSpec(const TimeseriesOptions& timeseriesOptions,
+                                                        const BSONObj& timeseriesIndexSpecBSON);
+
 /**
  * Maps the time-series collection index spec 'timeseriesIndexSpecBSON' to the index schema of the
  * underlying bucket collection using the information provided in 'timeseriesOptions'.