fix: forward forwarding-refs or change to const refs

include/dwarfs/conv.h

@@ -58,7 +58,7 @@ template <typename T, typename U>
 std::optional<bool> try_to(U&& s)
   requires(std::same_as<T, bool> && std::is_arithmetic_v<U>)
 {
-  return s != U{};
+  return std::forward<U>(s) != U{};
 }
 
 template <typename T>

include/dwarfs/writer/contextual_option.h

@@ -92,7 +92,7 @@ class contextual_option {
   template <typename T>
   bool any_is(T&& pred) const {
     for (auto e : contextual_) {
-      if (pred(e.second)) {
+      if (std::forward<T>(pred)(e.second)) {
         return true;
       }
     }
@@ -102,7 +102,7 @@ class contextual_option {
   template <typename T>
   void visit_contextual(T&& visitor) const {
     for (auto const& [ctx, val] : contextual_) {
-      visitor(ctx, val);
+      std::forward<T>(visitor)(ctx, val);
     }
   }
 

include/dwarfs/writer/internal/sortable_span.h

@@ -80,7 +80,7 @@ class sortable_span {
       : values_{values} {}
 
   template <typename P>
-  void select(P&& predicate) {
+  void select(P const& predicate) {
     index_.reserve(values_.size());
     for (size_t i = 0; i < values_.size(); ++i) {
       if (predicate(values_[i])) {

src/reader/internal/metadata_v2.cpp

@@ -324,7 +324,8 @@ void analyze_frozen(std::ostream& os,
 
 template <typename Function>
 void parse_metadata_options(
-    MappedFrozen<thrift::metadata::metadata> const& meta, Function&& func) {
+    MappedFrozen<thrift::metadata::metadata> const& meta,
+    Function const& func) {
   if (auto opt = meta.options()) {
     func("mtime_only", opt->mtime_only());
     func("packed_chunk_table", opt->packed_chunk_table());
@@ -765,7 +766,7 @@ class metadata_ final : public metadata_v2::impl {
 
   template <typename T>
   void walk(uint32_t self_index, uint32_t parent_index, set_type<int>& seen,
-            T&& func) const;
+            T const& func) const;
 
   template <typename T>
   void walk_tree(T&& func) const {
@@ -1557,7 +1558,7 @@ std::string metadata_<LoggerPolicy>::serialize_as_json(bool simple) const {
 template <typename LoggerPolicy>
 template <typename T>
 void metadata_<LoggerPolicy>::walk(uint32_t self_index, uint32_t parent_index,
-                                   set_type<int>& seen, T&& func) const {
+                                   set_type<int>& seen, T const& func) const {
   func(self_index, parent_index);
 
   auto entry = make_dir_entry_view_impl(self_index, parent_index);

src/writer/internal/file_scanner.cpp

@@ -77,7 +77,7 @@ class file_scanner_ final : public file_scanner::impl {
   void add_inode(file* p, int lineno);
 
   template <typename Lookup>
-  void finalize_hardlinks(Lookup&& lookup);
+  void finalize_hardlinks(Lookup const& lookup);
 
   template <bool UniqueOnly = false, typename KeyType>
   void finalize_files(folly::F14FastMap<KeyType, inode::files_vector>& fmap,
@@ -444,7 +444,7 @@ void file_scanner_<LoggerPolicy>::add_inode(file* p, int lineno) {
 
 template <typename LoggerPolicy>
 template <typename Lookup>
-void file_scanner_<LoggerPolicy>::finalize_hardlinks(Lookup&& lookup) {
+void file_scanner_<LoggerPolicy>::finalize_hardlinks(Lookup const& lookup) {
   auto tv = LOG_TIMED_VERBOSE;
 
   for (auto& kv : hardlinks_) {

src/writer/internal/inode_manager.cpp

@@ -384,7 +384,7 @@ class inode_ : public inode {
   void scan_range(mmif* mm, scanner_progress* sprog, size_t offset, size_t size,
                   size_t chunk_size, T&& scanner) {
     while (size >= chunk_size) {
-      scanner(mm->span(offset, chunk_size));
+      std::forward<T>(scanner)(mm->span(offset, chunk_size));
       mm->release_until(offset);
       offset += chunk_size;
       size -= chunk_size;

src/writer/internal/similarity_ordering.cpp

@@ -95,8 +95,8 @@ int distance(std::array<uint64_t, 4> const& a, std::array<uint64_t, 4> const& b)
 }
 
 template <typename GetI, typename GetK, typename Swap>
-void order_by_shortest_path(size_t count, GetI&& geti, GetK&& getk,
+void order_by_shortest_path(size_t count, GetI const& geti, GetK const& getk,
-                            Swap&& swapper) {
+                            Swap const& swapper) {
   for (size_t i = 0; i < count - 1; ++i) {
     auto bi = geti(i);
     int best_distance = std::numeric_limits<int>::max();

src/writer/segmenter.cpp

@@ -115,7 +115,8 @@ class fast_multimap {
   }
 
   template <typename F>
-  DWARFS_FORCE_INLINE void for_each_value(KeyT const& key, F&& func) const {
+  DWARFS_FORCE_INLINE void
+  for_each_value(KeyT const& key, F const& func) const {
     if (auto it = values_.find(key); it != values_.end()) [[unlikely]] {
       func(it->second);
       if (auto it2 = collisions_.find(key); it2 != collisions_.end())
@@ -128,7 +129,7 @@ class fast_multimap {
   }
 
   template <typename F>
-  DWARFS_FORCE_INLINE bool any_value_is(KeyT const& key, F&& func) const {
+  DWARFS_FORCE_INLINE bool any_value_is(KeyT const& key, F const& func) const {
     if (auto it = values_.find(key); it != values_.end()) [[unlikely]] {
       if (func(it->second)) {
         return true;
@@ -347,7 +348,7 @@ class ConstantGranularityPolicy : private GranularityPolicyBase {
   }
 
   template <typename T>
-  static DWARFS_FORCE_INLINE void for_bytes_in_frame(T&& func) {
+  static DWARFS_FORCE_INLINE void for_bytes_in_frame(T const& func) {
     for (size_t i = 0; i < kGranularity; ++i) {
       func();
     }
@@ -415,7 +416,7 @@ class VariableGranularityPolicy : private GranularityPolicyBase {
   }
 
   template <typename T>
-  DWARFS_FORCE_INLINE void for_bytes_in_frame(T&& func) const {
+  DWARFS_FORCE_INLINE void for_bytes_in_frame(T const& func) const {
     for (size_t i = 0; i < granularity_; ++i) {
       func();
     }