Cleanup: pass arguments by const reference

source/blender/draw/intern/draw_command.cc

@@ -501,7 +501,7 @@ std::string Draw::serialize() const
          ")";
 }
 
-std::string DrawMulti::serialize(std::string line_prefix) const
+std::string DrawMulti::serialize(const std::string &line_prefix) const
 {
   DrawMultiBuf::DrawGroupBuf &groups = multi_draw_buf->group_buf_;
 

source/blender/draw/intern/draw_command.hh

@@ -371,7 +371,7 @@ struct DrawMulti {
   uint uuid;
 
   void execute(RecordingState &state) const;
-  std::string serialize(std::string line_prefix) const;
+  std::string serialize(const std::string &line_prefix) const;
 };
 
 struct DrawIndirect {

source/blender/io/usd/hydra/volume_modifier.cc

@@ -123,7 +123,7 @@ void VolumeModifierData::write_transform()
   transform *= gf_matrix_from_transform(object->object_to_world().ptr());
 }
 
-std::string VolumeModifierData::get_cached_file_path(std::string directory, int frame)
+std::string VolumeModifierData::get_cached_file_path(const std::string &directory, int frame)
 {
   char file_path[FILE_MAX];
   char file_name[32];

source/blender/io/usd/hydra/volume_modifier.hh

@@ -25,7 +25,7 @@ class VolumeModifierData : public VolumeData {
   void write_transform() override;
 
  private:
-  std::string get_cached_file_path(std::string directory, int frame);
+  std::string get_cached_file_path(const std::string &directory, int frame);
 
   const FluidModifierData *modifier_;
 };

source/blender/io/wavefront_obj/tests/obj_exporter_tests.cc

@@ -161,7 +161,7 @@ class ObjExporterWriterTest : public testing::Test {
   }
 
   std::unique_ptr<OBJWriter> init_writer(const OBJExportParams &params,
-                                         const std::string out_filepath)
+                                         const std::string &out_filepath)
   {
     try {
       auto writer = std::make_unique<OBJWriter>(out_filepath.c_str(), params);

source/blender/makesrna/intern/rna_sequencer.cc

@@ -970,7 +970,7 @@ static int rna_Sequence_input_count_get(PointerRNA *ptr)
 }
 
 static void rna_Sequence_input_set(PointerRNA *ptr,
-                                   PointerRNA ptr_value,
+                                   const PointerRNA &ptr_value,
                                    ReportList *reports,
                                    int input_num)
 {

source/blender/python/intern/bpy_interface.cc

@@ -316,7 +316,7 @@ static _inittab bpy_internal_modules[] = {
  * Show an error just to avoid silent failure in the unlikely event something goes wrong,
  * in this case a developer will need to track down the root cause.
  */
-static void pystatus_exit_on_error(PyStatus status)
+static void pystatus_exit_on_error(const PyStatus &status)
 {
   if (UNLIKELY(PyStatus_Exception(status))) {
     fputs("Internal error initializing Python!\n", stderr);

source/blender/sequencer/intern/strip_retiming.cc

@@ -620,7 +620,7 @@ class RetimingRange {
 
   /* Create new range representing overlap of 2 ranges.
    * Returns overlapping range. */
-  RetimingRange operator*(const RetimingRange rhs_range)
+  RetimingRange operator*(const RetimingRange &rhs_range)
   {
     RetimingRange new_range = RetimingRange(0, 0, 0, LINEAR);
 
@@ -732,7 +732,7 @@ class RetimingRangeData {
     }
   }
 
-  RetimingRangeData &operator*=(const RetimingRangeData rhs)
+  RetimingRangeData &operator*=(const RetimingRangeData &rhs)
   {
     if (ranges.is_empty()) {
       for (const RetimingRange &rhs_range : rhs.ranges) {