Fix "unsafe narrowing" warnings in absl, 8/n.

Addresses failures with the following, in some files:
-Wshorten-64-to-32
-Wimplicit-int-conversion
-Wsign-compare
-Wsign-conversion
-Wtautological-unsigned-zero-compare

(This specific CL focuses on .cc files in */internal/.)

Bug: chromium:1292951
PiperOrigin-RevId: 471549854
Change-Id: Id685d0e4666212926f4e001b8ef4930b6a33a4cc

12 files changed, 211 insertions, 171 deletions

diff --git a/absl/base/internal/direct_mmap.h b/absl/base/internal/direct_mmap.h
index e492bb00..815b8d23 100644
--- a/absl/base/internal/direct_mmap.h
+++ b/absl/base/internal/direct_mmap.h
@@ -97,7 +97,8 @@ inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd,
 #ifdef __BIONIC__
   // SYS_mmap2 has problems on Android API level <= 16.
   // Workaround by invoking __mmap2() instead.
-  return __mmap2(start, length, prot, flags, fd, offset / pagesize);
+  return __mmap2(start, length, prot, flags, fd,
+                 static_cast<size_t>(offset / pagesize));
 #else
   return reinterpret_cast<void*>(
       syscall(SYS_mmap2, start, length, prot, flags, fd,
diff --git a/absl/base/internal/low_level_alloc.cc b/absl/base/internal/low_level_alloc.cc
index aa6c3c3c..662167b0 100644
--- a/absl/base/internal/low_level_alloc.cc
+++ b/absl/base/internal/low_level_alloc.cc
@@ -332,7 +332,7 @@ size_t GetPageSize() {
 #elif defined(__wasm__) || defined(__asmjs__)
   return getpagesize();
 #else
-  return sysconf(_SC_PAGESIZE);
+  return static_cast<size_t>(sysconf(_SC_PAGESIZE));
 #endif
 }
 
diff --git a/absl/base/internal/sysinfo.cc b/absl/base/internal/sysinfo.cc
index a3e08b93..d820ce38 100644
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -136,7 +136,7 @@ static int GetNumCPUs() {
   // Other possibilities:
   //  - Read /sys/devices/system/cpu/online and use cpumask_parse()
   //  - sysconf(_SC_NPROCESSORS_ONLN)
-  return std::thread::hardware_concurrency();
+  return static_cast<int>(std::thread::hardware_concurrency());
 #endif
 }
 
@@ -194,7 +194,7 @@ static bool ReadLongFromFile(const char *file, long *value) {
     char line[1024];
     char *err;
     memset(line, '\0', sizeof(line));
-    int len = read(fd, line, sizeof(line) - 1);
+    ssize_t len = read(fd, line, sizeof(line) - 1);
     if (len <= 0) {
       ret = false;
     } else {
@@ -376,7 +376,7 @@ pid_t GetTID() {
 #endif
 
 pid_t GetTID() {
-  return syscall(SYS_gettid);
+  return static_cast<pid_t>(syscall(SYS_gettid));
 }
 
 #elif defined(__akaros__)
@@ -429,11 +429,11 @@ static constexpr int kBitsPerWord = 32;  // tid_array is uint32_t.
 // Returns the TID to tid_array.
 static void FreeTID(void *v) {
   intptr_t tid = reinterpret_cast<intptr_t>(v);
-  int word = tid / kBitsPerWord;
+  intptr_t word = tid / kBitsPerWord;
   uint32_t mask = ~(1u << (tid % kBitsPerWord));
   absl::base_internal::SpinLockHolder lock(&tid_lock);
   assert(0 <= word && static_cast<size_t>(word) < tid_array->size());
-  (*tid_array)[word] &= mask;
+  (*tid_array)[static_cast<size_t>(word)] &= mask;
 }
 
 static void InitGetTID() {
@@ -455,7 +455,7 @@ pid_t GetTID() {
 
   intptr_t tid = reinterpret_cast<intptr_t>(pthread_getspecific(tid_key));
   if (tid != 0) {
-    return tid;
+    return static_cast<pid_t>(tid);
   }
 
   int bit;  // tid_array[word] = 1u << bit;
@@ -476,7 +476,8 @@ pid_t GetTID() {
     while (bit < kBitsPerWord && (((*tid_array)[word] >> bit) & 1) != 0) {
       ++bit;
     }
-    tid = (word * kBitsPerWord) + bit;
+    tid =
+        static_cast<intptr_t>((word * kBitsPerWord) + static_cast<size_t>(bit));
     (*tid_array)[word] |= 1u << bit;  // Mark the TID as allocated.
   }
 
diff --git a/absl/container/internal/btree.h b/absl/container/internal/btree.h
index 01f4e749..fb644cb2 100644
--- a/absl/container/internal/btree.h
+++ b/absl/container/internal/btree.h
@@ -634,27 +634,27 @@ class btree_node {
                               : NodeTargetSlots((begin + end) / 2 + 1, end);
   }
 
-  enum {
-    kTargetNodeSize = params_type::kTargetNodeSize,
-    kNodeTargetSlots = NodeTargetSlots(0, params_type::kTargetNodeSize),
-
-    // We need a minimum of 3 slots per internal node in order to perform
-    // splitting (1 value for the two nodes involved in the split and 1 value
-    // propagated to the parent as the delimiter for the split). For performance
-    // reasons, we don't allow 3 slots-per-node due to bad worst case occupancy
-    // of 1/3 (for a node, not a b-tree).
-    kMinNodeSlots = 4,
-
-    kNodeSlots =
-        kNodeTargetSlots >= kMinNodeSlots ? kNodeTargetSlots : kMinNodeSlots,
-
-    // The node is internal (i.e. is not a leaf node) if and only if `max_count`
-    // has this value.
-    kInternalNodeMaxCount = 0,
-  };
+  constexpr static size_type kTargetNodeSize = params_type::kTargetNodeSize;
+  constexpr static size_type kNodeTargetSlots =
+      NodeTargetSlots(0, kTargetNodeSize);
+
+  // We need a minimum of 3 slots per internal node in order to perform
+  // splitting (1 value for the two nodes involved in the split and 1 value
+  // propagated to the parent as the delimiter for the split). For performance
+  // reasons, we don't allow 3 slots-per-node due to bad worst case occupancy of
+  // 1/3 (for a node, not a b-tree).
+  constexpr static size_type kMinNodeSlots = 4;
+
+  constexpr static size_type kNodeSlots =
+      kNodeTargetSlots >= kMinNodeSlots ? kNodeTargetSlots : kMinNodeSlots;
+
+  // The node is internal (i.e. is not a leaf node) if and only if `max_count`
+  // has this value.
+  constexpr static field_type kInternalNodeMaxCount = 0;
 
   // Leaves can have less than kNodeSlots values.
-  constexpr static layout_type LeafLayout(const int slot_count = kNodeSlots) {
+  constexpr static layout_type LeafLayout(
+      const size_type slot_count = kNodeSlots) {
     return layout_type(
         /*parent*/ 1,
         /*generation*/ params_type::kEnableGenerations ? 1 : 0,
@@ -670,7 +670,7 @@ class btree_node {
         /*slots*/ kNodeSlots,
         /*children*/ kNodeSlots + 1);
   }
-  constexpr static size_type LeafSize(const int slot_count = kNodeSlots) {
+  constexpr static size_type LeafSize(const size_type slot_count = kNodeSlots) {
     return LeafLayout(slot_count).AllocSize();
   }
   constexpr static size_type InternalSize() {
@@ -693,10 +693,10 @@ class btree_node {
   }
   void set_parent(btree_node *p) { *GetField<0>() = p; }
   field_type &mutable_finish() { return GetField<2>()[2]; }
-  slot_type *slot(int i) { return &GetField<3>()[i]; }
+  slot_type* slot(size_type i) { return &GetField<3>()[i]; }
   slot_type *start_slot() { return slot(start()); }
   slot_type *finish_slot() { return slot(finish()); }
-  const slot_type *slot(int i) const { return &GetField<3>()[i]; }
+  const slot_type* slot(size_type i) const { return &GetField<3>()[i]; }
   void set_position(field_type v) { GetField<2>()[0] = v; }
   void set_start(field_type v) { GetField<2>()[1] = v; }
   void set_finish(field_type v) { GetField<2>()[2] = v; }
@@ -773,52 +773,55 @@ class btree_node {
   }
 
   // Getters for the key/value at position i in the node.
-  const key_type &key(int i) const { return params_type::key(slot(i)); }
-  reference value(int i) { return params_type::element(slot(i)); }
-  const_reference value(int i) const { return params_type::element(slot(i)); }
+  const key_type& key(size_type i) const { return params_type::key(slot(i)); }
+  reference value(size_type i) { return params_type::element(slot(i)); }
+  const_reference value(size_type i) const {
+    return params_type::element(slot(i));
+  }
 
   // Getters/setter for the child at position i in the node.
-  btree_node *child(int i) const { return GetField<4>()[i]; }
+  btree_node* child(field_type i) const { return GetField<4>()[i]; }
   btree_node *start_child() const { return child(start()); }
-  btree_node *&mutable_child(int i) { return GetField<4>()[i]; }
-  void clear_child(int i) {
+  btree_node*& mutable_child(field_type i) { return GetField<4>()[i]; }
+  void clear_child(field_type i) {
     absl::container_internal::SanitizerPoisonObject(&mutable_child(i));
   }
-  void set_child(int i, btree_node *c) {
+  void set_child(field_type i, btree_node* c) {
     absl::container_internal::SanitizerUnpoisonObject(&mutable_child(i));
     mutable_child(i) = c;
     c->set_position(i);
   }
-  void init_child(int i, btree_node *c) {
+  void init_child(field_type i, btree_node* c) {
     set_child(i, c);
     c->set_parent(this);
   }
 
   // Returns the position of the first value whose key is not less than k.
   template <typename K>
-  SearchResult<int, is_key_compare_to::value> lower_bound(
-      const K &k, const key_compare &comp) const {
+  SearchResult<size_type, is_key_compare_to::value> lower_bound(
+      const K& k,
+      const key_compare& comp) const {
     return use_linear_search::value ? linear_search(k, comp)
                                     : binary_search(k, comp);
   }
   // Returns the position of the first value whose key is greater than k.
   template <typename K>
-  int upper_bound(const K &k, const key_compare &comp) const {
+  size_type upper_bound(const K& k, const key_compare& comp) const {
     auto upper_compare = upper_bound_adapter<key_compare>(comp);
     return use_linear_search::value ? linear_search(k, upper_compare).value
                                     : binary_search(k, upper_compare).value;
   }
 
   template <typename K, typename Compare>
-  SearchResult<int, btree_is_key_compare_to<Compare, key_type>::value>
-  linear_search(const K &k, const Compare &comp) const {
+  SearchResult<size_type, btree_is_key_compare_to<Compare, key_type>::value>
+  linear_search(const K& k, const Compare& comp) const {
     return linear_search_impl(k, start(), finish(), comp,
                               btree_is_key_compare_to<Compare, key_type>());
   }
 
   template <typename K, typename Compare>
-  SearchResult<int, btree_is_key_compare_to<Compare, key_type>::value>
-  binary_search(const K &k, const Compare &comp) const {
+  SearchResult<size_type, btree_is_key_compare_to<Compare, key_type>::value>
+  binary_search(const K& k, const Compare& comp) const {
     return binary_search_impl(k, start(), finish(), comp,
                               btree_is_key_compare_to<Compare, key_type>());
   }
@@ -826,8 +829,11 @@ class btree_node {
   // Returns the position of the first value whose key is not less than k using
   // linear search performed using plain compare.
   template <typename K, typename Compare>
-  SearchResult<int, false> linear_search_impl(
-      const K &k, int s, const int e, const Compare &comp,
+  SearchResult<size_type, false> linear_search_impl(
+      const K& k,
+      size_type s,
+      const size_type e,
+      const Compare& comp,
       std::false_type /* IsCompareTo */) const {
     while (s < e) {
       if (!comp(key(s), k)) {
@@ -835,14 +841,17 @@ class btree_node {
       }
       ++s;
     }
-    return SearchResult<int, false>{s};
+    return SearchResult<size_type, false>{s};
   }
 
   // Returns the position of the first value whose key is not less than k using
   // linear search performed using compare-to.
   template <typename K, typename Compare>
-  SearchResult<int, true> linear_search_impl(
-      const K &k, int s, const int e, const Compare &comp,
+  SearchResult<size_type, true> linear_search_impl(
+      const K& k,
+      size_type s,
+      const size_type e,
+      const Compare& comp,
       std::true_type /* IsCompareTo */) const {
     while (s < e) {
       const absl::weak_ordering c = comp(key(s), k);
@@ -859,30 +868,36 @@ class btree_node {
   // Returns the position of the first value whose key is not less than k using
   // binary search performed using plain compare.
   template <typename K, typename Compare>
-  SearchResult<int, false> binary_search_impl(
-      const K &k, int s, int e, const Compare &comp,
+  SearchResult<size_type, false> binary_search_impl(
+      const K& k,
+      size_type s,
+      size_type e,
+      const Compare& comp,
       std::false_type /* IsCompareTo */) const {
     while (s != e) {
-      const int mid = (s + e) >> 1;
+      const size_type mid = (s + e) >> 1;
       if (comp(key(mid), k)) {
         s = mid + 1;
       } else {
         e = mid;
       }
     }
-    return SearchResult<int, false>{s};
+    return SearchResult<size_type, false>{s};
   }
 
   // Returns the position of the first value whose key is not less than k using
   // binary search performed using compare-to.
   template <typename K, typename CompareTo>
-  SearchResult<int, true> binary_search_impl(
-      const K &k, int s, int e, const CompareTo &comp,
+  SearchResult<size_type, true> binary_search_impl(
+      const K& k,
+      size_type s,
+      size_type e,
+      const CompareTo& comp,
       std::true_type /* IsCompareTo */) const {
     if (params_type::template can_have_multiple_equivalent_keys<K>()) {
       MatchKind exact_match = MatchKind::kNe;
       while (s != e) {
-        const int mid = (s + e) >> 1;
+        const size_type mid = (s + e) >> 1;
         const absl::weak_ordering c = comp(key(mid), k);
         if (c < 0) {
           s = mid + 1;
@@ -899,7 +914,7 @@ class btree_node {
       return {s, exact_match};
     } else {  // Can't have multiple equivalent keys.
       while (s != e) {
-        const int mid = (s + e) >> 1;
+        const size_type mid = (s + e) >> 1;
         const absl::weak_ordering c = comp(key(mid), k);
         if (c < 0) {
           s = mid + 1;
@@ -916,7 +931,7 @@ class btree_node {
   // Emplaces a value at position i, shifting all existing values and
   // children at positions >= i to the right by 1.
   template <typename... Args>
-  void emplace_value(size_type i, allocator_type *alloc, Args &&... args);
+  void emplace_value(field_type i, allocator_type* alloc, Args&&... args);
 
   // Removes the values at positions [i, i + to_erase), shifting all existing
   // values and children after that range to the left by to_erase. Clears all
@@ -924,10 +939,12 @@ class btree_node {
   void remove_values(field_type i, field_type to_erase, allocator_type *alloc);
 
   // Rebalances a node with its right sibling.
-  void rebalance_right_to_left(int to_move, btree_node *right,
-                               allocator_type *alloc);
-  void rebalance_left_to_right(int to_move, btree_node *right,
-                               allocator_type *alloc);
+  void rebalance_right_to_left(field_type to_move,
+                               btree_node* right,
+                               allocator_type* alloc);
+  void rebalance_left_to_right(field_type to_move,
+                               btree_node* right,
+                               allocator_type* alloc);
 
   // Splits a node, moving a portion of the node's values to its right sibling.
   void split(int insert_position, btree_node *dest, allocator_type *alloc);
@@ -937,7 +954,7 @@ class btree_node {
   void merge(btree_node *src, allocator_type *alloc);
 
   // Node allocation/deletion routines.
-  void init_leaf(int max_count, btree_node *parent) {
+  void init_leaf(field_type max_count, btree_node* parent) {
     set_generation(0);
     set_parent(parent);
     set_position(0);
@@ -1034,6 +1051,7 @@ class btree_node {
 
 template <typename Node, typename Reference, typename Pointer>
 class btree_iterator {
+  using field_type = typename Node::field_type;
   using key_type = typename Node::key_type;
   using size_type = typename Node::size_type;
   using params_type = typename Node::params_type;
@@ -1105,7 +1123,7 @@ class btree_iterator {
     ABSL_HARDENING_ASSERT(node_->start() <= position_);
     ABSL_HARDENING_ASSERT(node_->finish() > position_);
     assert_valid_generation();
-    return node_->value(position_);
+    return node_->value(static_cast<field_type>(position_));
   }
   pointer operator->() const { return &operator*(); }
 
@@ -1189,9 +1207,11 @@ class btree_iterator {
 #endif
   }
 
-  const key_type &key() const { return node_->key(position_); }
+  const key_type& key() const {
+    return node_->key(static_cast<size_type>(position_));
+  }
   decltype(std::declval<Node *>()->slot(0)) slot() {
-    return node_->slot(position_);
+    return node_->slot(static_cast<size_type>(position_));
   }
 
   void assert_valid_generation() const {
@@ -1600,7 +1620,7 @@ class btree {
 
   // Allocates a correctly aligned node of at least size bytes using the
   // allocator.
-  node_type *allocate(const size_type size) {
+  node_type* allocate(size_type size) {
     return reinterpret_cast<node_type *>(
         absl::container_internal::Allocate<node_type::Alignment()>(
             mutable_allocator(), size));
@@ -1617,7 +1637,7 @@ class btree {
     n->init_leaf(kNodeSlots, parent);
     return n;
   }
-  node_type *new_leaf_root_node(const int max_count) {
+  node_type* new_leaf_root_node(field_type max_count) {
     node_type *n = allocate(node_type::LeafSize(max_count));
     n->init_leaf(max_count, /*parent=*/n);
     return n;
@@ -1685,8 +1705,9 @@ class btree {
   iterator internal_find(const K &key) const;
 
   // Verifies the tree structure of node.
-  int internal_verify(const node_type *node, const key_type *lo,
-                      const key_type *hi) const;
+  size_type internal_verify(const node_type* node,
+                            const key_type* lo,
+                            const key_type* hi) const;
 
   node_stats internal_stats(const node_type *node) const {
     // The root can be a static empty node.
@@ -1720,9 +1741,9 @@ class btree {
 // btree_node methods
 template <typename P>
 template <typename... Args>
-inline void btree_node<P>::emplace_value(const size_type i,
-                                         allocator_type *alloc,
-                                         Args &&... args) {
+inline void btree_node<P>::emplace_value(const field_type i,
+                                         allocator_type* alloc,
+                                         Args&&... args) {
   assert(i >= start());
   assert(i <= finish());
   // Shift old values to create space for new value and then construct it in
@@ -1731,7 +1752,7 @@ inline void btree_node<P>::emplace_value(const size_type i,
     transfer_n_backward(finish() - i, /*dest_i=*/i + 1, /*src_i=*/i, this,
                         alloc);
   }
-  value_init(i, alloc, std::forward<Args>(args)...);
+  value_init(static_cast<field_type>(i), alloc, std::forward<Args>(args)...);
   set_finish(finish() + 1);
 
   if (is_internal() && finish() > i + 1) {
@@ -1767,9 +1788,9 @@ inline void btree_node<P>::remove_values(const field_type i,
 }
 
 template <typename P>
-void btree_node<P>::rebalance_right_to_left(const int to_move,
-                                            btree_node *right,
-                                            allocator_type *alloc) {
+void btree_node<P>::rebalance_right_to_left(field_type to_move,
+                                            btree_node* right,
+                                            allocator_type* alloc) {
   assert(parent() == right->parent());
   assert(position() + 1 == right->position());
   assert(right->count() >= count());
@@ -1791,10 +1812,10 @@ void btree_node<P>::rebalance_right_to_left(const int to_move,
 
   if (is_internal()) {
     // Move the child pointers from the right to the left node.
-    for (int i = 0; i < to_move; ++i) {
+    for (field_type i = 0; i < to_move; ++i) {
       init_child(finish() + i + 1, right->child(i));
     }
-    for (int i = right->start(); i <= right->finish() - to_move; ++i) {
+    for (field_type i = right->start(); i <= right->finish() - to_move; ++i) {
       assert(i + to_move <= right->max_count());
       right->init_child(i, right->child(i + to_move));
       right->clear_child(i + to_move);
@@ -1807,9 +1828,9 @@ void btree_node<P>::rebalance_right_to_left(const int to_move,
 }
 
 template <typename P>
-void btree_node<P>::rebalance_left_to_right(const int to_move,
-                                            btree_node *right,
-                                            allocator_type *alloc) {
+void btree_node<P>::rebalance_left_to_right(field_type to_move,
+                                            btree_node* right,
+                                            allocator_type* alloc) {
   assert(parent() == right->parent());
   assert(position() + 1 == right->position());
   assert(count() >= right->count());
@@ -1838,11 +1859,11 @@ void btree_node<P>::rebalance_left_to_right(const int to_move,
 
   if (is_internal()) {
     // Move the child pointers from the left to the right node.
-    for (int i = right->finish(); i >= right->start(); --i) {
-      right->init_child(i + to_move, right->child(i));
-      right->clear_child(i);
+    for (field_type i = right->finish() + 1; i > right->start(); --i) {
+      right->init_child(i - 1 + to_move, right->child(i - 1));
+      right->clear_child(i - 1);
     }
-    for (int i = 1; i <= to_move; ++i) {
+    for (field_type i = 1; i <= to_move; ++i) {
       right->init_child(i - 1, child(finish() - to_move + i));
       clear_child(finish() - to_move + i);
     }
@@ -1883,7 +1904,7 @@ void btree_node<P>::split(const int insert_position, btree_node *dest,
   parent()->init_child(position() + 1, dest);
 
   if (is_internal()) {
-    for (int i = dest->start(), j = finish() + 1; i <= dest->finish();
+    for (field_type i = dest->start(), j = finish() + 1; i <= dest->finish();
          ++i, ++j) {
       assert(child(j) != nullptr);
       dest->init_child(i, child(j));
@@ -1944,15 +1965,15 @@ void btree_node<P>::clear_and_delete(btree_node *node, allocator_type *alloc) {
   // instead of checking whether the parent is a leaf, we can remove this logic.
   btree_node *leftmost_leaf = node;
 #endif
-  // Use `int` because `pos` needs to be able to hold `kNodeSlots+1`, which
-  // isn't guaranteed to be a valid `field_type`.
-  int pos = node->position();
+  // Use `size_type` because `pos` needs to be able to hold `kNodeSlots+1`,
+  // which isn't guaranteed to be a valid `field_type`.
+  size_type pos = node->position();
   btree_node *parent = node->parent();
   for (;;) {
     // In each iteration of the next loop, we delete one leaf node and go right.
     assert(pos <= parent->finish());
     do {
-      node = parent->child(pos);
+      node = parent->child(static_cast<field_type>(pos));
       if (node->is_internal()) {
         // Navigate to the leftmost leaf under node.
         while (node->is_internal()) node = node->start_child();
@@ -2004,7 +2025,7 @@ void btree_iterator<N, R, P>::increment_slow() {
     }
   } else {
     assert(position_ < node_->finish());
-    node_ = node_->child(position_ + 1);
+    node_ = node_->child(static_cast<field_type>(position_ + 1));
     while (node_->is_internal()) {
       node_ = node_->start_child();
     }
@@ -2028,7 +2049,7 @@ void btree_iterator<N, R, P>::decrement_slow() {
     }
   } else {
     assert(position_ >= node_->start());
-    node_ = node_->child(position_);
+    node_ = node_->child(static_cast<field_type>(position_));
     while (node_->is_internal()) {
       node_ = node_->child(node_->finish());
     }
@@ -2475,16 +2496,19 @@ void btree<P>::rebalance_or_split(iterator *iter) {
         // We bias rebalancing based on the position being inserted. If we're
         // inserting at the end of the right node then we bias rebalancing to
         // fill up the left node.
-        int to_move = (kNodeSlots - left->count()) /
-                      (1 + (insert_position < static_cast<int>(kNodeSlots)));
-        to_move = (std::max)(1, to_move);
-
-        if (insert_position - to_move >= node->start() ||
-            left->count() + to_move < static_cast<int>(kNodeSlots)) {
+        field_type to_move =
+            (kNodeSlots - left->count()) /
+            (1 + (static_cast<field_type>(insert_position) < kNodeSlots));
+        to_move = (std::max)(field_type{1}, to_move);
+
+        if (static_cast<field_type>(insert_position) - to_move >=
+                node->start() ||
+            left->count() + to_move < kNodeSlots) {
           left->rebalance_right_to_left(to_move, node, mutable_allocator());
 
           assert(node->max_count() - node->count() == to_move);
-          insert_position = insert_position - to_move;
+          insert_position = static_cast<int>(
+              static_cast<field_type>(insert_position) - to_move);
           if (insert_position < node->start()) {
             insert_position = insert_position + left->count() + 1;
             node = left;
@@ -2504,12 +2528,13 @@ void btree<P>::rebalance_or_split(iterator *iter) {
         // We bias rebalancing based on the position being inserted. If we're
         // inserting at the beginning of the left node then we bias rebalancing
         // to fill up the right node.
-        int to_move = (static_cast<int>(kNodeSlots) - right->count()) /
-                      (1 + (insert_position > node->start()));
-        to_move = (std::max)(1, to_move);
+        field_type to_move = (kNodeSlots - right->count()) /
+                             (1 + (insert_position > node->start()));
+        to_move = (std::max)(field_type{1}, to_move);
 
-        if (insert_position <= node->finish() - to_move ||
-            right->count() + to_move < static_cast<int>(kNodeSlots)) {
+        if (static_cast<field_type>(insert_position) <=
+                node->finish() - to_move ||
+            right->count() + to_move < kNodeSlots) {
           node->rebalance_left_to_right(to_move, right, mutable_allocator());
 
           if (insert_position > node->finish()) {
@@ -2594,8 +2619,9 @@ bool btree<P>::try_merge_or_rebalance(iterator *iter) {
     // from the front of the tree.
     if (right->count() > kMinNodeValues &&
         (iter->node_->count() == 0 || iter->position_ > iter->node_->start())) {
-      int to_move = (right->count() - iter->node_->count()) / 2;
-      to_move = (std::min)(to_move, right->count() - 1);
+      field_type to_move = (right->count() - iter->node_->count()) / 2;
+      to_move =
+          (std::min)(to_move, static_cast<field_type>(right->count() - 1));
       iter->node_->rebalance_right_to_left(to_move, right, mutable_allocator());
       return false;
     }
@@ -2609,8 +2635,8 @@ bool btree<P>::try_merge_or_rebalance(iterator *iter) {
     if (left->count() > kMinNodeValues &&
         (iter->node_->count() == 0 ||
          iter->position_ < iter->node_->finish())) {
-      int to_move = (left->count() - iter->node_->count()) / 2;
-      to_move = (std::min)(to_move, left->count() - 1);
+      field_type to_move = (left->count() - iter->node_->count()) / 2;
+      to_move = (std::min)(to_move, static_cast<field_type>(left->count() - 1));
       left->rebalance_left_to_right(to_move, iter->node_, mutable_allocator());
       iter->position_ += to_move;
       return false;
@@ -2671,8 +2697,9 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args)
       // Insertion into the root where the root is smaller than the full node
       // size. Simply grow the size of the root node.
       assert(iter.node_ == root());
-      iter.node_ =
-          new_leaf_root_node((std::min<int>)(kNodeSlots, 2 * max_count));
+      iter.node_ = new_leaf_root_node(
+          static_cast<field_type>((std::min)(static_cast<int>(kNodeSlots),
+                                             2 * max_count)));
       // Transfer the values from the old root to the new root.
       node_type *old_root = root();
       node_type *new_root = iter.node_;
@@ -2687,7 +2714,8 @@ inline auto btree<P>::internal_emplace(iterator iter, Args &&... args)
       rebalance_or_split(&iter);
     }
   }
-  iter.node_->emplace_value(iter.position_, alloc, std::forward<Args>(args)...);
+  iter.node_->emplace_value(static_cast<field_type>(iter.position_), alloc,
+                            std::forward<Args>(args)...);
   ++size_;
   iter.update_generation();
   return iter;
@@ -2699,9 +2727,9 @@ inline auto btree<P>::internal_locate(const K &key) const
     -> SearchResult<iterator, is_key_compare_to::value> {
   iterator iter(const_cast<node_type *>(root()));
   for (;;) {
-    SearchResult<int, is_key_compare_to::value> res =
+    SearchResult<size_type, is_key_compare_to::value> res =
         iter.node_->lower_bound(key, key_comp());
-    iter.position_ = res.value;
+    iter.position_ = static_cast<int>(res.value);
     if (res.IsEq()) {
       return {iter, MatchKind::kEq};
     }
@@ -2712,7 +2740,7 @@ inline auto btree<P>::internal_locate(const K &key) const
     if (iter.node_->is_leaf()) {
       break;
     }
-    iter.node_ = iter.node_->child(iter.position_);
+    iter.node_ = iter.node_->child(static_cast<field_type>(iter.position_));
   }
   // Note: in the non-key-compare-to case, the key may actually be equivalent
   // here (and the MatchKind::kNe is ignored).
@@ -2729,16 +2757,16 @@ auto btree<P>::internal_lower_bound(const K &key) const
     return ret;
   }
   iterator iter(const_cast<node_type *>(root()));
-  SearchResult<int, is_key_compare_to::value> res;
+  SearchResult<size_type, is_key_compare_to::value> res;
   bool seen_eq = false;
   for (;;) {
     res = iter.node_->lower_bound(key, key_comp());
-    iter.position_ = res.value;
+    iter.position_ = static_cast<int>(res.value);
     if (iter.node_->is_leaf()) {
       break;
     }
     seen_eq = seen_eq || res.IsEq();
-    iter.node_ = iter.node_->child(iter.position_);
+    iter.node_ = iter.node_->child(static_cast<field_type>(iter.position_));
   }
   if (res.IsEq()) return {iter, MatchKind::kEq};
   return {internal_last(iter), seen_eq ? MatchKind::kEq : MatchKind::kNe};
@@ -2749,11 +2777,11 @@ template <typename K>
 auto btree<P>::internal_upper_bound(const K &key) const -> iterator {
   iterator iter(const_cast<node_type *>(root()));
   for (;;) {
-    iter.position_ = iter.node_->upper_bound(key, key_comp());
+    iter.position_ = static_cast<int>(iter.node_->upper_bound(key, key_comp()));
     if (iter.node_->is_leaf()) {
       break;
     }
-    iter.node_ = iter.node_->child(iter.position_);
+    iter.node_ = iter.node_->child(static_cast<field_type>(iter.position_));
   }
   return internal_last(iter);
 }
@@ -2776,8 +2804,10 @@ auto btree<P>::internal_find(const K &key) const -> iterator {
 }
 
 template <typename P>
-int btree<P>::internal_verify(const node_type *node, const key_type *lo,
-                              const key_type *hi) const {
+typename btree<P>::size_type btree<P>::internal_verify(
+    const node_type* node,
+    const key_type* lo,
+    const key_type* hi) const {
   assert(node->count() > 0);
   assert(node->count() <= node->max_count());
   if (lo) {
@@ -2789,9 +2819,9 @@ int btree<P>::internal_verify(const node_type *node, const key_type *lo,
   for (int i = node->start() + 1; i < node->finish(); ++i) {
     assert(!compare_keys(node->key(i), node->key(i - 1)));
   }
-  int count = node->count();
+  size_type count = node->count();
   if (node->is_internal()) {
-    for (int i = node->start(); i <= node->finish(); ++i) {
+    for (field_type i = node->start(); i <= node->finish(); ++i) {
       assert(node->child(i) != nullptr);
       assert(node->child(i)->parent() == node);
       assert(node->child(i)->position() == i);
diff --git a/absl/container/internal/inlined_vector.h b/absl/container/internal/inlined_vector.h
index fdca3061..a56b7573 100644
--- a/absl/container/internal/inlined_vector.h
+++ b/absl/container/internal/inlined_vector.h
@@ -641,8 +641,8 @@ auto Storage<T, N, A>::Insert(ConstIterator<A> pos, ValueAdapter values,
                               SizeType<A> insert_count) -> Iterator<A> {
   StorageView<A> storage_view = MakeStorageView();
 
-  SizeType<A> insert_index =
-      std::distance(ConstIterator<A>(storage_view.data), pos);
+  auto insert_index = static_cast<SizeType<A>>(
+      std::distance(ConstIterator<A>(storage_view.data), pos));
   SizeType<A> insert_end_index = insert_index + insert_count;
   SizeType<A> new_size = storage_view.size + insert_count;
 
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index b8118cd2..93de2221 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -612,9 +612,9 @@ struct GroupAArch64Impl {
 
   NonIterableBitMask<uint64_t, kWidth, 3> MaskEmpty() const {
     uint64_t mask =
-        vget_lane_u64(vreinterpret_u64_u8(
-                          vceq_s8(vdup_n_s8(static_cast<h2_t>(ctrl_t::kEmpty)),
-                                  vreinterpret_s8_u8(ctrl))),
+        vget_lane_u64(vreinterpret_u64_u8(vceq_s8(
+                          vdup_n_s8(static_cast<int8_t>(ctrl_t::kEmpty)),
+                          vreinterpret_s8_u8(ctrl))),
                       0);
     return NonIterableBitMask<uint64_t, kWidth, 3>(mask);
   }
@@ -1144,11 +1144,12 @@ class raw_hash_set {
           std::is_nothrow_default_constructible<key_equal>::value&&
               std::is_nothrow_default_constructible<allocator_type>::value) {}
 
-  explicit raw_hash_set(size_t bucket_count, const hasher& hash = hasher(),
+  explicit raw_hash_set(size_t bucket_count,
+                        const hasher& hash = hasher(),
                         const key_equal& eq = key_equal(),
                         const allocator_type& alloc = allocator_type())
       : ctrl_(EmptyGroup()),
-        settings_(0, HashtablezInfoHandle(), hash, eq, alloc) {
+        settings_(0u, HashtablezInfoHandle(), hash, eq, alloc) {
     if (bucket_count) {
       capacity_ = NormalizeCapacity(bucket_count);
       initialize_slots();
@@ -1273,14 +1274,16 @@ class raw_hash_set {
               std::is_nothrow_copy_constructible<allocator_type>::value)
       : ctrl_(absl::exchange(that.ctrl_, EmptyGroup())),
         slots_(absl::exchange(that.slots_, nullptr)),
-        size_(absl::exchange(that.size_, 0)),
-        capacity_(absl::exchange(that.capacity_, 0)),
+        size_(absl::exchange(that.size_, size_t{0})),
+        capacity_(absl::exchange(that.capacity_, size_t{0})),
         // Hash, equality and allocator are copied instead of moved because
         // `that` must be left valid. If Hash is std::function<Key>, moving it
         // would create a nullptr functor that cannot be called.
-        settings_(absl::exchange(that.growth_left(), 0),
+        settings_(absl::exchange(that.growth_left(), size_t{0}),
                   absl::exchange(that.infoz(), HashtablezInfoHandle()),
-                  that.hash_ref(), that.eq_ref(), that.alloc_ref()) {}
+                  that.hash_ref(),
+                  that.eq_ref(),
+                  that.alloc_ref()) {}
 
   raw_hash_set(raw_hash_set&& that, const allocator_type& a)
       : ctrl_(EmptyGroup()),
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index 55892d77..cc656f9d 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -406,7 +406,7 @@ template <typename StorageT>
 StorageT* FlagImpl::OffsetValue() const {
   char* p = reinterpret_cast<char*>(const_cast<FlagImpl*>(this));
   // The offset is deduced via Flag value type specific op_.
-  size_t offset = flags_internal::ValueOffset(op_);
+  ptrdiff_t offset = flags_internal::ValueOffset(op_);
 
   return reinterpret_cast<StorageT*>(p + offset);
 }
@@ -486,7 +486,7 @@ bool FlagImpl::ReadOneBool() const {
 }
 
 void FlagImpl::ReadSequenceLockedData(void* dst) const {
-  int size = Sizeof(op_);
+  size_t size = Sizeof(op_);
   // Attempt to read using the sequence lock.
   if (ABSL_PREDICT_TRUE(seq_lock_.TryRead(dst, AtomicBufferValue(), size))) {
     return;
diff --git a/absl/flags/internal/usage.cc b/absl/flags/internal/usage.cc
index 949709e8..a3b13ed3 100644
--- a/absl/flags/internal/usage.cc
+++ b/absl/flags/internal/usage.cc
@@ -148,8 +148,7 @@ class FlagHelpPrettyPrinter {
       }
 
       // Write the token, ending the string first if necessary/possible.
-      if (!new_line &&
-          (line_len_ + static_cast<int>(token.size()) >= max_line_len_)) {
+      if (!new_line && (line_len_ + token.size() >= max_line_len_)) {
         EndLine();
         new_line = true;
       }
diff --git a/absl/profiling/internal/exponential_biased_test.cc b/absl/profiling/internal/exponential_biased_test.cc
index 6a6c317e..ebfbcad4 100644
--- a/absl/profiling/internal/exponential_biased_test.cc
+++ b/absl/profiling/internal/exponential_biased_test.cc
@@ -94,13 +94,14 @@ double AndersonDarlingPValue(int n, double z) {
 }
 
 double AndersonDarlingStatistic(const std::vector<double>& random_sample) {
-  int n = random_sample.size();
+  size_t n = random_sample.size();
   double ad_sum = 0;
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     ad_sum += (2 * i + 1) *
               std::log(random_sample[i] * (1 - random_sample[n - 1 - i]));
   }
-  double ad_statistic = -n - 1 / static_cast<double>(n) * ad_sum;
+  const auto n_as_double = static_cast<double>(n);
+  double ad_statistic = -n_as_double - 1 / n_as_double * ad_sum;
   return ad_statistic;
 }
 
@@ -111,14 +112,15 @@ double AndersonDarlingStatistic(const std::vector<double>& random_sample) {
 // Marsaglia and Marsaglia for details.
 double AndersonDarlingTest(const std::vector<double>& random_sample) {
   double ad_statistic = AndersonDarlingStatistic(random_sample);
-  double p = AndersonDarlingPValue(random_sample.size(), ad_statistic);
+  double p = AndersonDarlingPValue(static_cast<int>(random_sample.size()),
+                                   ad_statistic);
   return p;
 }
 
 TEST(ExponentialBiasedTest, CoinTossDemoWithGetSkipCount) {
   ExponentialBiased eb;
   for (int runs = 0; runs < 10; ++runs) {
-    for (int flips = eb.GetSkipCount(1); flips > 0; --flips) {
+    for (int64_t flips = eb.GetSkipCount(1); flips > 0; --flips) {
       printf("head...");
     }
     printf("tail\n");
@@ -132,7 +134,7 @@ TEST(ExponentialBiasedTest, CoinTossDemoWithGetSkipCount) {
 
 TEST(ExponentialBiasedTest, SampleDemoWithStride) {
   ExponentialBiased eb;
-  int stride = eb.GetStride(10);
+  int64_t stride = eb.GetStride(10);
   int samples = 0;
   for (int i = 0; i < 10000000; ++i) {
     if (--stride == 0) {
@@ -147,7 +149,7 @@ TEST(ExponentialBiasedTest, SampleDemoWithStride) {
 // Testing that NextRandom generates uniform random numbers. Applies the
 // Anderson-Darling test for uniformity
 TEST(ExponentialBiasedTest, TestNextRandom) {
-  for (auto n : std::vector<int>({
+  for (auto n : std::vector<size_t>({
            10,  // Check short-range correlation
            100, 1000,
            10000  // Make sure there's no systemic error
@@ -161,7 +163,7 @@ TEST(ExponentialBiasedTest, TestNextRandom) {
     }
     std::vector<uint64_t> int_random_sample(n);
     // Collect samples
-    for (int i = 0; i < n; i++) {
+    for (size_t i = 0; i < n; i++) {
       int_random_sample[i] = x;
       x = ExponentialBiased::NextRandom(x);
     }
@@ -169,7 +171,7 @@ TEST(ExponentialBiasedTest, TestNextRandom) {
     std::sort(int_random_sample.begin(), int_random_sample.end());
     std::vector<double> random_sample(n);
     // Convert them to uniform randoms (in the range [0,1])
-    for (int i = 0; i < n; i++) {
+    for (size_t i = 0; i < n; i++) {
       random_sample[i] =
           static_cast<double>(int_random_sample[i]) / max_prng_value;
     }
diff --git a/absl/random/internal/seed_material.cc b/absl/random/internal/seed_material.cc
index c03cad85..1041302b 100644
--- a/absl/random/internal/seed_material.cc
+++ b/absl/random/internal/seed_material.cc
@@ -173,12 +173,12 @@ bool ReadSeedMaterialFromDevURandom(absl::Span<uint32_t> values) {
   }
 
   while (success && buffer_size > 0) {
-    int bytes_read = read(dev_urandom, buffer, buffer_size);
+    ssize_t bytes_read = read(dev_urandom, buffer, buffer_size);
     int read_error = errno;
     success = (bytes_read > 0);
     if (success) {
       buffer += bytes_read;
-      buffer_size -= bytes_read;
+      buffer_size -= static_cast<size_t>(bytes_read);
     } else if (bytes_read == -1 && read_error == EINTR) {
       success = true;  // Need to try again.
     }
diff --git a/absl/synchronization/internal/futex.h b/absl/synchronization/internal/futex.h
index 06fbd6d0..cb97da09 100644
--- a/absl/synchronization/internal/futex.h
+++ b/absl/synchronization/internal/futex.h
@@ -87,7 +87,7 @@ class FutexImpl {
  public:
   static int WaitUntil(std::atomic<int32_t> *v, int32_t val,
                        KernelTimeout t) {
-    int err = 0;
+    long err = 0;  // NOLINT(runtime/int)
     if (t.has_timeout()) {
       // https://locklessinc.com/articles/futex_cheat_sheet/
       // Unlike FUTEX_WAIT, FUTEX_WAIT_BITSET uses absolute time.
@@ -105,41 +105,44 @@ class FutexImpl {
                     FUTEX_WAIT | FUTEX_PRIVATE_FLAG, val, nullptr);
     }
     if (ABSL_PREDICT_FALSE(err != 0)) {
-      err = -errno;
+      return -errno;
     }
-    return err;
+    return 0;
   }
 
   static int WaitBitsetAbsoluteTimeout(std::atomic<int32_t> *v, int32_t val,
                                        int32_t bits,
                                        const struct timespec *abstime) {
-    int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v),
-                      FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG, val, abstime,
-                      nullptr, bits);
+    // NOLINTNEXTLINE(runtime/int)
+    long err = syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
+                       FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG, val, abstime,
+                       nullptr, bits);
     if (ABSL_PREDICT_FALSE(err != 0)) {
-      err = -errno;
+      return -errno;
     }
-    return err;
+    return 0;
   }
 
   static int Wake(std::atomic<int32_t> *v, int32_t count) {
-    int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v),
-                      FUTEX_WAKE | FUTEX_PRIVATE_FLAG, count);
+    // NOLINTNEXTLINE(runtime/int)
+    long err = syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
+                       FUTEX_WAKE | FUTEX_PRIVATE_FLAG, count);
     if (ABSL_PREDICT_FALSE(err < 0)) {
-      err = -errno;
+      return -errno;
     }
-    return err;
+    return 0;
   }
 
   // FUTEX_WAKE_BITSET
   static int WakeBitset(std::atomic<int32_t> *v, int32_t count, int32_t bits) {
-    int err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v),
-                      FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG, count, nullptr,
-                      nullptr, bits);
+    // NOLINTNEXTLINE(runtime/int)
+    long err = syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
+                       FUTEX_WAKE_BITSET | FUTEX_PRIVATE_FLAG, count, nullptr,
+                       nullptr, bits);
     if (ABSL_PREDICT_FALSE(err < 0)) {
-      err = -errno;
+      return -errno;
     }
-    return err;
+    return 0;
   }
 };
 
diff --git a/absl/time/internal/test_util.cc b/absl/time/internal/test_util.cc
index 454b33a1..4b7849c6 100644
--- a/absl/time/internal/test_util.cc
+++ b/absl/time/internal/test_util.cc
@@ -84,14 +84,15 @@ class TestZoneInfoSource : public cctz::ZoneInfoSource {
       : data_(data), end_(data + size) {}
 
   std::size_t Read(void* ptr, std::size_t size) override {
-    const std::size_t len = std::min<std::size_t>(size, end_ - data_);
+    const std::size_t len =
+        std::min(size, static_cast<std::size_t>(end_ - data_));
     memcpy(ptr, data_, len);
     data_ += len;
     return len;
   }
 
   int Skip(std::size_t offset) override {
-    data_ += std::min<std::size_t>(offset, end_ - data_);
+    data_ += std::min(offset, static_cast<std::size_t>(end_ - data_));
     return 0;
   }