SERVER-90577 Enable tidy check performance-inefficient-string-concatenation (#22270)

GitOrigin-RevId: e163558464d2dcde48e6c448167b9c552f691f6b

.clang-tidy.in

@@ -66,6 +66,7 @@ Checks:          '-*,
                   performance-for-range-copy,
                   performance-implicit-conversion-in-loop,
                   performance-inefficient-algorithm,
+                  performance-inefficient-string-concatenation,
                   performance-move-constructor-init,
                   performance-no-automatic-move,
                   performance-trivially-destructible,
@@ -120,7 +121,6 @@ Checks:          '-*,
                   -modernize-use-emplace,
                   -modernize-use-noexcept,
                   -modernize-use-uncaught-exceptions,
-                  -performance-inefficient-string-concatenation,
                   -performance-inefficient-vector-operation,
                   -performance-unnecessary-value-param,
                   -readability-delete-null-pointer,

src/mongo/client/sdam/server_selection_json_test_runner.cpp

@@ -544,7 +544,7 @@ public:
         std::string result;
         for (size_t i = 0; i < errors.size(); ++i) {
             auto error = errors[i];
-            result = result + error.first + " - " + error.second;
+            result += error.first += " - "s += error.second;
             if (i != errors.size() - 1) {
                 result += "; ";
             }

src/mongo/db/bson/dotted_path_support_test.cpp

@@ -198,9 +198,10 @@ TEST(ExtractAllElementsAlongPath, NestedObjectWithScalarValue) {
 TEST(ExtractAllElementsAlongPath, NestedMaxDepthObjectWithScalarValue) {
     BSONObj obj = BSON("a" << 1);
     std::string dotted_path = "a";
+    dotted_path.reserve(1 + BSONDepth::getMaxAllowableDepth() * 2);
     for (uint32_t i = 0; i < BSONDepth::getMaxAllowableDepth(); ++i) {
         obj = BSON("a" << obj);
-        dotted_path = "a." + dotted_path;
+        dotted_path.insert(0, "a.");
     }
 
     BSONElementSet actualElements;

src/mongo/db/pipeline/change_stream_rewrite_helpers.cpp

@@ -36,6 +36,7 @@
 #include <boost/optional/optional.hpp>
 #include <boost/smart_ptr.hpp>
 #include <cstddef>
+#include <fmt/format.h>
 #include <functional>
 #include <map>
 #include <ostream>
@@ -555,9 +556,10 @@ std::unique_ptr<MatchExpression> matchRewriteUpdateDescription(
                 // not need to check whether the predicate matches a missing field in this case.
                 static const std::vector<std::string> oplogFields = {"o.diff.d", "o.$unset"};
                 auto rewrittenEquality = std::make_unique<OrMatchExpression>();
+                using namespace fmt::literals;
                 for (auto&& oplogField : oplogFields) {
                     rewrittenEquality->add(std::make_unique<ExistsMatchExpression>(
-                        StringData(oplogField + "." + fieldName)));
+                        StringData("{}.{}"_format(oplogField, fieldName))));
                 }
                 return rewrittenEquality;
             };

src/mongo/util/options_parser/options_parser.cpp

@@ -57,6 +57,7 @@
 #include <cstring>
 #include <exception>
 #include <fcntl.h>
+#include <fmt/format.h>
 #include <fstream>  // IWYU pragma: keep
 #include <iterator>
 #include <map>
@@ -994,7 +995,8 @@ Status addYAMLNodesToEnvironment(const YAML::Node& root,
             // If this is not a special field name, and we are in a sub object, append our
             // current fieldName to the selector for the sub object we are traversing
             else {
-                dottedName = parentPath + '.' + fieldName;
+                using namespace fmt::literals;
+                dottedName = "{}.{}"_format(parentPath, fieldName);
             }
         }