Enable -Wconversion

Makefile

@@ -231,10 +231,6 @@ endif
 CXX11_CHECK_CMD = $(CXX) -std=c++11 -o $(TMPOUT) -c test/build/c++11.cc
 HAS_CXX11 = $(shell $(CXX11_CHECK_CMD) 2> /dev/null && echo true || echo false)
 
-# Detect if -Wshorten-64-to-32 is a thing
-SHORTEN_64_TO_32_CHECK_CMD = $(CC) -Wshorten-64-to-32 test/build/empty.c
-HAS_SHORTEN_64_TO_32 = $(shell $(SHORTEN_64_TO_32_CHECK_CMD) 2> /dev/null && echo true || echo false)
-
 # The HOST compiler settings are used to compile the protoc plugins.
 # In most cases, you won't have to change anything, but if you are
 # cross-compiling, you can override these variables from GNU make's
@@ -249,10 +245,7 @@ ifdef EXTRA_DEFINES
 DEFINES += $(EXTRA_DEFINES)
 endif
 
-CFLAGS += -std=c89 -pedantic -Wsign-conversion
+CFLAGS += -std=c89 -pedantic -Wsign-conversion -Wconversion
-ifeq ($(HAS_SHORTEN_64_TO_32),true)
-CFLAGS += -Wshorten-64-to-32
-endif
 ifeq ($(HAS_CXX11),true)
 CXXFLAGS += -std=c++11
 else

src/core/channel/compress_filter.c

@@ -230,7 +230,10 @@ static void process_send_ops(grpc_call_element *elem,
         GPR_ASSERT(calld->remaining_slice_bytes > 0);
         /* Increase input ref count, gpr_slice_buffer_add takes ownership.  */
         gpr_slice_buffer_add(&calld->slices, gpr_slice_ref(sop->data.slice));
-        calld->remaining_slice_bytes -= GPR_SLICE_LENGTH(sop->data.slice);
+        GPR_ASSERT(GPR_SLICE_LENGTH(sop->data.slice) >
+                   calld->remaining_slice_bytes);
+        calld->remaining_slice_bytes -=
+            (gpr_uint32)GPR_SLICE_LENGTH(sop->data.slice);
         if (calld->remaining_slice_bytes == 0) {
           did_compress =
               compress_send_sb(calld->compression_algorithm, &calld->slices);

src/core/client_config/resolvers/sockaddr_resolver.c

@@ -218,7 +218,7 @@ static int parse_ipv4(grpc_uri *uri, struct sockaddr_storage *addr,
       gpr_log(GPR_ERROR, "invalid ipv4 port: '%s'", port);
       goto done;
     }
-    in->sin_port = htons(port_num);
+    in->sin_port = htons((gpr_uint16)port_num);
   } else {
     gpr_log(GPR_ERROR, "no port given for ipv4 scheme");
     goto done;
@@ -259,7 +259,7 @@ static int parse_ipv6(grpc_uri *uri, struct sockaddr_storage *addr,
       gpr_log(GPR_ERROR, "invalid ipv6 port: '%s'", port);
       goto done;
     }
-    in6->sin6_port = htons(port_num);
+    in6->sin6_port = htons((gpr_uint16)port_num);
   } else {
     gpr_log(GPR_ERROR, "no port given for ipv6 scheme");
     goto done;

src/core/iomgr/alarm.c

@@ -123,13 +123,13 @@ static size_t shard_idx(const grpc_alarm *info) {
 }
 
 static double ts_to_dbl(gpr_timespec ts) {
-  return ts.tv_sec + 1e-9 * ts.tv_nsec;
+  return (double)ts.tv_sec + 1e-9 * ts.tv_nsec;
 }
 
 static gpr_timespec dbl_to_ts(double d) {
   gpr_timespec ts;
-  ts.tv_sec = d;
+  ts.tv_sec = (time_t)d;
-  ts.tv_nsec = 1e9 * (d - ts.tv_sec);
+  ts.tv_nsec = (int)(1e9 * (d - (double)ts.tv_sec));
   ts.clock_type = GPR_TIMESPAN;
   return ts;
 }

src/core/iomgr/pollset_multipoller_with_poll_posix.c

@@ -140,7 +140,7 @@ static void multipoll_with_poll_pollset_maybe_work(
   gpr_mu_unlock(&pollset->mu);
 
   for (i = 1; i < pfd_count; i++) {
-    pfds[i].events = grpc_fd_begin_poll(watchers[i].fd, pollset, POLLIN,
+    pfds[i].events = (short)grpc_fd_begin_poll(watchers[i].fd, pollset, POLLIN,
                                                POLLOUT, &watchers[i]);
   }
 

src/core/iomgr/pollset_posix.c

@@ -443,7 +443,7 @@ static void basic_pollset_maybe_work(grpc_pollset *pollset,
     pfd[1].revents = 0;
     gpr_mu_unlock(&pollset->mu);
     pfd[1].events =
-        grpc_fd_begin_poll(fd, pollset, POLLIN, POLLOUT, &fd_watcher);
+        (short)grpc_fd_begin_poll(fd, pollset, POLLIN, POLLOUT, &fd_watcher);
     if (pfd[1].events != 0) {
       nfds++;
     }

src/core/iomgr/sockaddr_utils.c

@@ -123,15 +123,17 @@ void grpc_sockaddr_make_wildcards(int port, struct sockaddr_in *wild4_out,
 }
 
 void grpc_sockaddr_make_wildcard4(int port, struct sockaddr_in *wild_out) {
+  GPR_ASSERT(port >= 0 && port < 65536);
   memset(wild_out, 0, sizeof(*wild_out));
   wild_out->sin_family = AF_INET;
-  wild_out->sin_port = htons(port);
+  wild_out->sin_port = htons((gpr_uint16)port);
 }
 
 void grpc_sockaddr_make_wildcard6(int port, struct sockaddr_in6 *wild_out) {
+  GPR_ASSERT(port >= 0 && port < 65536);
   memset(wild_out, 0, sizeof(*wild_out));
   wild_out->sin6_family = AF_INET6;
-  wild_out->sin6_port = htons(port);
+  wild_out->sin6_port = htons((gpr_uint16)port);
 }
 
 int grpc_sockaddr_to_string(char **out, const struct sockaddr *addr,
@@ -215,10 +217,12 @@ int grpc_sockaddr_get_port(const struct sockaddr *addr) {
 int grpc_sockaddr_set_port(const struct sockaddr *addr, int port) {
   switch (addr->sa_family) {
     case AF_INET:
-      ((struct sockaddr_in *)addr)->sin_port = htons(port);
+      GPR_ASSERT(port >= 0 && port < 65536);
+      ((struct sockaddr_in *)addr)->sin_port = htons((gpr_uint16)port);
       return 1;
     case AF_INET6:
-      ((struct sockaddr_in6 *)addr)->sin6_port = htons(port);
+      GPR_ASSERT(port >= 0 && port < 65536);
+      ((struct sockaddr_in6 *)addr)->sin6_port = htons((gpr_uint16)port);
       return 1;
     default:
       gpr_log(GPR_ERROR, "Unknown socket family %d in grpc_sockaddr_set_port",

src/core/surface/call.c

@@ -421,7 +421,7 @@ static grpc_cq_completion *allocate_completion(grpc_call *call) {
     if (call->allocated_completions & (1u << i)) {
       continue;
     }
-    call->allocated_completions |= 1u << i;
+    call->allocated_completions |= (gpr_uint8)(1u << i);
     gpr_mu_unlock(&call->completion_mu);
     return &call->completions[i];
   }
@@ -432,7 +432,8 @@ static grpc_cq_completion *allocate_completion(grpc_call *call) {
 static void done_completion(void *call, grpc_cq_completion *completion) {
   grpc_call *c = call;
   gpr_mu_lock(&c->completion_mu);
-  c->allocated_completions &= ~(1u << (completion - c->completions));
+  c->allocated_completions &=
+      (gpr_uint8) ~(1u << (completion - c->completions));
   gpr_mu_unlock(&c->completion_mu);
   GRPC_CALL_INTERNAL_UNREF(c, "completion", 1);
 }
@@ -743,7 +744,7 @@ static void finish_live_ioreq_op(grpc_call *call, grpc_ioreq_op op,
   size_t i;
   /* ioreq is live: we need to do something */
   master = &call->masters[master_set];
-  master->complete_mask |= 1u << op;
+  master->complete_mask |= (gpr_uint16)(1u << op);
   if (!success) {
     master->success = 0;
   }
@@ -1214,7 +1215,7 @@ static grpc_call_error start_ioreq(grpc_call *call, const grpc_ioreq *reqs,
                                    grpc_ioreq_completion_func completion,
                                    void *user_data) {
   size_t i;
-  gpr_uint32 have_ops = 0;
+  gpr_uint16 have_ops = 0;
   grpc_ioreq_op op;
   reqinfo_master *master;
   grpc_ioreq_data data;
@@ -1251,7 +1252,7 @@ static grpc_call_error start_ioreq(grpc_call *call, const grpc_ioreq *reqs,
                            GRPC_MDSTR_REF(reqs[i].data.send_status.details));
       }
     }
-    have_ops |= 1u << op;
+    have_ops |= (gpr_uint16)(1u << op);
 
     call->request_data[op] = data;
     call->request_flags[op] = reqs[i].flags;

src/core/transport/chttp2/bin_encoder.c

@@ -128,12 +128,13 @@ gpr_slice grpc_chttp2_huffman_compress(gpr_slice input) {
 
     while (temp_length > 8) {
       temp_length -= 8;
-      *out++ = temp >> temp_length;
+      *out++ = (gpr_uint8)(temp >> temp_length);
     }
   }
 
   if (temp_length) {
-    *out++ = (temp << (8u - temp_length)) | (0xffu >> temp_length);
+    *out++ = (gpr_uint8)(temp << (8u - temp_length)) |
+             (gpr_uint8)(0xffu >> temp_length);
   }
 
   GPR_ASSERT(out == GPR_SLICE_END_PTR(output));
@@ -150,7 +151,7 @@ typedef struct {
 static void enc_flush_some(huff_out *out) {
   while (out->temp_length > 8) {
     out->temp_length -= 8;
-    *out->out++ = out->temp >> out->temp_length;
+    *out->out++ = (gpr_uint8)(out->temp >> out->temp_length);
   }
 }
 
@@ -189,8 +190,9 @@ gpr_slice grpc_chttp2_base64_encode_and_huffman_compress(gpr_slice input) {
 
   /* encode full triplets */
   for (i = 0; i < input_triplets; i++) {
-    enc_add2(&out, in[0] >> 2, ((in[0] & 0x3) << 4) | (in[1] >> 4));
+    enc_add2(&out, in[0] >> 2, (gpr_uint8)((in[0] & 0x3) << 4) | (in[1] >> 4));
-    enc_add2(&out, ((in[1] & 0xf) << 2) | (in[2] >> 6), in[2] & 0x3f);
+    enc_add2(&out, (gpr_uint8)((in[1] & 0xf) << 2) | (in[2] >> 6),
+             (gpr_uint8)(in[2] & 0x3f));
     in += 3;
   }
 
@@ -199,19 +201,20 @@ gpr_slice grpc_chttp2_base64_encode_and_huffman_compress(gpr_slice input) {
     case 0:
       break;
     case 1:
-      enc_add2(&out, in[0] >> 2, (in[0] & 0x3) << 4);
+      enc_add2(&out, in[0] >> 2, (gpr_uint8)((in[0] & 0x3) << 4));
       in += 1;
       break;
     case 2:
-      enc_add2(&out, in[0] >> 2, ((in[0] & 0x3) << 4) | (in[1] >> 4));
+      enc_add2(&out, in[0] >> 2,
-      enc_add1(&out, (in[1] & 0xf) << 2);
+               (gpr_uint8)((in[0] & 0x3) << 4) | (gpr_uint8)(in[1] >> 4));
+      enc_add1(&out, (gpr_uint8)((in[1] & 0xf) << 2));
       in += 2;
       break;
   }
 
   if (out.temp_length) {
-    *out.out++ =
+    *out.out++ = (gpr_uint8)(out.temp << (8u - out.temp_length)) |
-        (out.temp << (8u - out.temp_length)) | (0xffu >> out.temp_length);
+                 (gpr_uint8)(0xffu >> out.temp_length);
   }
 
   GPR_ASSERT(out.out <= GPR_SLICE_END_PTR(output));

src/core/transport/chttp2/frame_data.c

@@ -161,7 +161,8 @@ grpc_chttp2_parse_error grpc_chttp2_data_parser_parse(
         grpc_sopb_add_slice(
             &p->incoming_sopb,
             gpr_slice_sub(slice, (size_t)(cur - beg), (size_t)(end - beg)));
-        p->frame_size -= (end - cur);
+        GPR_ASSERT(end - cur <= p->frame_size);
+        p->frame_size -= (gpr_uint32)(end - cur);
         return GRPC_CHTTP2_PARSE_OK;
       }
   }

src/core/transport/chttp2/frame_goaway.c

@@ -137,7 +137,8 @@ grpc_chttp2_parse_error grpc_chttp2_goaway_parser_parse(
     /* fallthrough */
     case GRPC_CHTTP2_GOAWAY_DEBUG:
       memcpy(p->debug_data + p->debug_pos, cur, (size_t)(end - cur));
-      p->debug_pos += end - cur;
+      GPR_ASSERT(end - cur < GPR_UINT32_MAX - p->debug_pos);
+      p->debug_pos += (gpr_uint32)(end - cur);
       p->state = GRPC_CHTTP2_GOAWAY_DEBUG;
       if (is_last) {
         transport_parsing->goaway_received = 1;
@@ -165,9 +166,9 @@ void grpc_chttp2_goaway_append(gpr_uint32 last_stream_id, gpr_uint32 error_code,
   frame_length = 4 + 4 + (gpr_uint32)GPR_SLICE_LENGTH(debug_data);
 
   /* frame header: length */
-  *p++ = frame_length >> 16;
+  *p++ = (gpr_uint8)(frame_length >> 16);
-  *p++ = frame_length >> 8;
+  *p++ = (gpr_uint8)(frame_length >> 8);
-  *p++ = frame_length;
+  *p++ = (gpr_uint8)(frame_length);
   /* frame header: type */
   *p++ = GRPC_CHTTP2_FRAME_GOAWAY;
   /* frame header: flags */
@@ -178,15 +179,15 @@ void grpc_chttp2_goaway_append(gpr_uint32 last_stream_id, gpr_uint32 error_code,
   *p++ = 0;
   *p++ = 0;
   /* payload: last stream id */
-  *p++ = last_stream_id >> 24;
+  *p++ = (gpr_uint8)(last_stream_id >> 24);
-  *p++ = last_stream_id >> 16;
+  *p++ = (gpr_uint8)(last_stream_id >> 16);
-  *p++ = last_stream_id >> 8;
+  *p++ = (gpr_uint8)(last_stream_id >> 8);
-  *p++ = last_stream_id;
+  *p++ = (gpr_uint8)(last_stream_id);
   /* payload: error code */
-  *p++ = error_code >> 24;
+  *p++ = (gpr_uint8)(error_code >> 24);
-  *p++ = error_code >> 16;
+  *p++ = (gpr_uint8)(error_code >> 16);
-  *p++ = error_code >> 8;
+  *p++ = (gpr_uint8)(error_code >> 8);
-  *p++ = error_code;
+  *p++ = (gpr_uint8)(error_code);
   GPR_ASSERT(p == GPR_SLICE_END_PTR(header));
   gpr_slice_buffer_add(slice_buffer, header);
   gpr_slice_buffer_add(slice_buffer, debug_data);

src/core/transport/chttp2/frame_rst_stream.c

@@ -47,14 +47,14 @@ gpr_slice grpc_chttp2_rst_stream_create(gpr_uint32 id, gpr_uint32 code) {
   *p++ = 4;
   *p++ = GRPC_CHTTP2_FRAME_RST_STREAM;
   *p++ = 0;
-  *p++ = id >> 24;
+  *p++ = (gpr_uint8)(id >> 24);
-  *p++ = id >> 16;
+  *p++ = (gpr_uint8)(id >> 16);
-  *p++ = id >> 8;
+  *p++ = (gpr_uint8)(id >> 8);
-  *p++ = id;
+  *p++ = (gpr_uint8)(id);
-  *p++ = code >> 24;
+  *p++ = (gpr_uint8)(code >> 24);
-  *p++ = code >> 16;
+  *p++ = (gpr_uint8)(code >> 16);
-  *p++ = code >> 8;
+  *p++ = (gpr_uint8)(code >> 8);
-  *p++ = code;
+  *p++ = (gpr_uint8)(code);
 
   return slice;
 }

src/core/transport/chttp2/frame_settings.c

@@ -61,9 +61,9 @@ const grpc_chttp2_setting_parameters
 
 static gpr_uint8 *fill_header(gpr_uint8 *out, gpr_uint32 length,
                               gpr_uint8 flags) {
-  *out++ = length >> 16;
+  *out++ = (gpr_uint8)(length >> 16);
-  *out++ = length >> 8;
+  *out++ = (gpr_uint8)(length >> 8);
-  *out++ = length;
+  *out++ = (gpr_uint8)(length);
   *out++ = GRPC_CHTTP2_FRAME_SETTINGS;
   *out++ = flags;
   *out++ = 0;
@@ -90,12 +90,12 @@ gpr_slice grpc_chttp2_settings_create(gpr_uint32 *old, const gpr_uint32 *new,
   for (i = 0; i < count; i++) {
     if (new[i] != old[i] || (force_mask & (1u << i)) != 0) {
       GPR_ASSERT(i);
-      *p++ = i >> 8;
+      *p++ = (gpr_uint8)(i >> 8);
-      *p++ = i;
+      *p++ = (gpr_uint8)(i);
-      *p++ = new[i] >> 24;
+      *p++ = (gpr_uint8)(new[i] >> 24);
-      *p++ = new[i] >> 16;
+      *p++ = (gpr_uint8)(new[i] >> 16);
-      *p++ = new[i] >> 8;
+      *p++ = (gpr_uint8)(new[i] >> 8);
-      *p++ = new[i];
+      *p++ = (gpr_uint8)(new[i]);
       old[i] = new[i];
     }
   }
@@ -162,7 +162,7 @@ grpc_chttp2_parse_error grpc_chttp2_settings_parser_parse(
           }
           return GRPC_CHTTP2_PARSE_OK;
         }
-        parser->id = ((gpr_uint16)*cur) << 8;
+        parser->id = (gpr_uint16)(((gpr_uint16)*cur) << 8);
         cur++;
       /* fallthrough */
       case GRPC_CHTTP2_SPS_ID1:
@@ -170,7 +170,7 @@ grpc_chttp2_parse_error grpc_chttp2_settings_parser_parse(
           parser->state = GRPC_CHTTP2_SPS_ID1;
           return GRPC_CHTTP2_PARSE_OK;
         }
-        parser->id |= (*cur);
+        parser->id = (gpr_uint16)(parser->id | (*cur));
         cur++;
       /* fallthrough */
       case GRPC_CHTTP2_SPS_VAL0:

src/core/transport/chttp2/frame_window_update.c

@@ -48,14 +48,14 @@ gpr_slice grpc_chttp2_window_update_create(gpr_uint32 id,
   *p++ = 4;
   *p++ = GRPC_CHTTP2_FRAME_WINDOW_UPDATE;
   *p++ = 0;
-  *p++ = id >> 24;
+  *p++ = (gpr_uint8)(id >> 24);
-  *p++ = id >> 16;
+  *p++ = (gpr_uint8)(id >> 16);
-  *p++ = id >> 8;
+  *p++ = (gpr_uint8)(id >> 8);
-  *p++ = id;
+  *p++ = (gpr_uint8)(id);
-  *p++ = window_update >> 24;
+  *p++ = (gpr_uint8)(window_update >> 24);
-  *p++ = window_update >> 16;
+  *p++ = (gpr_uint8)(window_update >> 16);
-  *p++ = window_update >> 8;
+  *p++ = (gpr_uint8)(window_update >> 8);
-  *p++ = window_update;
+  *p++ = (gpr_uint8)(window_update);
 
   return slice;
 }

src/core/transport/chttp2/hpack_parser.c

@@ -1090,7 +1090,8 @@ static void append_bytes(grpc_chttp2_hpack_parser_string *str,
     str->str = gpr_realloc(str->str, str->capacity);
   }
   memcpy(str->str + str->length, data, length);
-  str->length += length;
+  GPR_ASSERT(length <= GPR_UINT32_MAX - str->length);
+  str->length += (gpr_uint32)length;
 }
 
 static int append_string(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
@@ -1158,9 +1159,9 @@ static int append_string(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
         goto b64_byte3;
       p->base64_buffer |= bits;
       bits = p->base64_buffer;
-      decoded[0] = bits >> 16;
+      decoded[0] = (gpr_uint8)(bits >> 16);
-      decoded[1] = bits >> 8;
+      decoded[1] = (gpr_uint8)(bits >> 8);
-      decoded[2] = bits;
+      decoded[2] = (gpr_uint8)(bits);
       append_bytes(str, decoded, 3);
       goto b64_byte0;
   }
@@ -1190,7 +1191,7 @@ static int finish_str(grpc_chttp2_hpack_parser *p) {
                 bits & 0xffff);
         return 0;
       }
-      decoded[0] = bits >> 16;
+      decoded[0] = (gpr_uint8)(bits >> 16);
       append_bytes(str, decoded, 1);
       break;
     case B64_BYTE3:
@@ -1200,8 +1201,8 @@ static int finish_str(grpc_chttp2_hpack_parser *p) {
                 bits & 0xff);
         return 0;
       }
-      decoded[0] = bits >> 16;
+      decoded[0] = (gpr_uint8)(bits >> 16);
-      decoded[1] = bits >> 8;
+      decoded[1] = (gpr_uint8)(bits >> 8);
       append_bytes(str, decoded, 2);
       break;
   }
@@ -1256,7 +1257,8 @@ static int parse_string(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
            parse_next(p, cur + remaining, end);
   } else {
     if (!add_str_bytes(p, cur, cur + given)) return 0;
-    p->strgot += given;
+    GPR_ASSERT(given <= GPR_UINT32_MAX - p->strgot);
+    p->strgot += (gpr_uint32)given;
     p->state = parse_string;
     return 1;
   }

src/core/transport/chttp2/hpack_table.c

@@ -150,17 +150,20 @@ grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
 /* Evict one element from the table */
 static void evict1(grpc_chttp2_hptbl *tbl) {
   grpc_mdelem *first_ent = tbl->ents[tbl->first_ent];
-  tbl->mem_used -= GPR_SLICE_LENGTH(first_ent->key->slice) +
+  size_t elem_bytes = GPR_SLICE_LENGTH(first_ent->key->slice) +
                       GPR_SLICE_LENGTH(first_ent->value->slice) +
                       GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
-  tbl->first_ent = (tbl->first_ent + 1) % GRPC_CHTTP2_MAX_TABLE_COUNT;
+  GPR_ASSERT(elem_bytes <= tbl->mem_used);
+  tbl->mem_used = (gpr_uint16)(tbl->mem_used - elem_bytes);
+  tbl->first_ent =
+      (gpr_uint16)((tbl->first_ent + 1) % GRPC_CHTTP2_MAX_TABLE_COUNT);
   tbl->num_ents--;
   GRPC_MDELEM_UNREF(first_ent);
 }
 
 void grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   /* determine how many bytes of buffer this entry represents */
-  gpr_uint16 elem_bytes = GPR_SLICE_LENGTH(md->key->slice) +
+  size_t elem_bytes = GPR_SLICE_LENGTH(md->key->slice) +
                       GPR_SLICE_LENGTH(md->value->slice) +
                       GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
 
@@ -182,7 +185,7 @@ void grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   }
 
   /* evict entries to ensure no overflow */
-  while (elem_bytes > tbl->max_bytes - tbl->mem_used) {
+  while (elem_bytes > (size_t)tbl->max_bytes - tbl->mem_used) {
     evict1(tbl);
   }
 
@@ -190,28 +193,30 @@ void grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   tbl->ents[tbl->last_ent] = md;
 
   /* update accounting values */
-  tbl->last_ent = (tbl->last_ent + 1) % GRPC_CHTTP2_MAX_TABLE_COUNT;
+  tbl->last_ent =
+      (gpr_uint16)((tbl->last_ent + 1) % GRPC_CHTTP2_MAX_TABLE_COUNT);
   tbl->num_ents++;
-  tbl->mem_used += elem_bytes;
+  tbl->mem_used = (gpr_uint16)(tbl->mem_used + elem_bytes);
 }
 
 grpc_chttp2_hptbl_find_result grpc_chttp2_hptbl_find(
     const grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   grpc_chttp2_hptbl_find_result r = {0, 0};
-  int i;
+  gpr_uint16 i;
 
   /* See if the string is in the static table */
   for (i = 0; i < GRPC_CHTTP2_LAST_STATIC_ENTRY; i++) {
     grpc_mdelem *ent = tbl->static_ents[i];
     if (md->key != ent->key) continue;
-    r.index = i + 1;
+    r.index = (gpr_uint16)(i + 1);
     r.has_value = md->value == ent->value;
     if (r.has_value) return r;
   }
 
   /* Scan the dynamic table */
   for (i = 0; i < tbl->num_ents; i++) {
-    int idx = tbl->num_ents - i + GRPC_CHTTP2_LAST_STATIC_ENTRY;
+    gpr_uint16 idx =
+        (gpr_uint16)(tbl->num_ents - i + GRPC_CHTTP2_LAST_STATIC_ENTRY);
     grpc_mdelem *ent =
         tbl->ents[(tbl->first_ent + i) % GRPC_CHTTP2_MAX_TABLE_COUNT];
     if (md->key != ent->key) continue;

src/core/transport/chttp2/internal.h

@@ -168,7 +168,7 @@ typedef struct {
   grpc_iomgr_closure *pending_closures_tail;
 
   /** window available for us to send to peer */
-  gpr_uint32 outgoing_window;
+  gpr_int64 outgoing_window;
   /** window available for peer to send to us - updated after parse */
   gpr_uint32 incoming_window;
   /** how much window would we like to have for incoming_window */
@@ -280,7 +280,7 @@ struct grpc_chttp2_transport_parsing {
   gpr_uint32 goaway_last_stream_index;
   gpr_slice goaway_text;
 
-  gpr_uint64 outgoing_window_update;
+  gpr_int64 outgoing_window_update;
 
   /** pings awaiting responses */
   grpc_chttp2_outstanding_ping pings;

src/core/transport/chttp2/parsing.c

@@ -411,7 +411,7 @@ int grpc_chttp2_perform_read(grpc_chttp2_transport_parsing *transport_parsing,
                                0)) {
           return 0;
         }
-        transport_parsing->incoming_frame_size -= (end - cur);
+        transport_parsing->incoming_frame_size -= (gpr_uint32)(end - cur);
         return 1;
       }
       gpr_log(GPR_ERROR, "should never reach here");
@@ -479,7 +479,7 @@ static void skip_header(void *tp, grpc_mdelem *md) { GRPC_MDELEM_UNREF(md); }
 static int init_skip_frame_parser(
     grpc_chttp2_transport_parsing *transport_parsing, int is_header) {
   if (is_header) {
-    int is_eoh = transport_parsing->expect_continuation_stream_id != 0;
+    gpr_uint8 is_eoh = transport_parsing->expect_continuation_stream_id != 0;
     transport_parsing->parser = grpc_chttp2_header_parser_parse;
     transport_parsing->parser_data = &transport_parsing->hpack_parser;
     transport_parsing->hpack_parser.on_header = skip_header;
@@ -622,7 +622,7 @@ static void on_header(void *tp, grpc_mdelem *md) {
 
 static int init_header_frame_parser(
     grpc_chttp2_transport_parsing *transport_parsing, int is_continuation) {
-  int is_eoh = (transport_parsing->incoming_frame_flags &
+  gpr_uint8 is_eoh = (transport_parsing->incoming_frame_flags &
                       GRPC_CHTTP2_DATA_FLAG_END_HEADERS) != 0;
   int via_accept = 0;
   grpc_chttp2_stream_parsing *stream_parsing;

src/core/transport/chttp2/stream_encoder.c

@@ -77,15 +77,15 @@ typedef struct {
 static void fill_header(gpr_uint8 *p, gpr_uint8 type, gpr_uint32 id, size_t len,
                         gpr_uint8 flags) {
   GPR_ASSERT(len < 16777316);
-  *p++ = len >> 16;
+  *p++ = (gpr_uint8)(len >> 16);
-  *p++ = len >> 8;
+  *p++ = (gpr_uint8)(len >> 8);
-  *p++ = len;
+  *p++ = (gpr_uint8)(len);
   *p++ = type;
   *p++ = flags;
-  *p++ = id >> 24;
+  *p++ = (gpr_uint8)(id >> 24);
-  *p++ = id >> 16;
+  *p++ = (gpr_uint8)(id >> 16);
-  *p++ = id >> 8;
+  *p++ = (gpr_uint8)(id >> 8);
-  *p++ = id;
+  *p++ = (gpr_uint8)(id);
 }
 
 /* finish a frame - fill in the previously reserved header */
@@ -106,11 +106,12 @@ static void finish_frame(framer_state *st, int is_header_boundary,
     case NONE:
       return;
   }
-  fill_header(GPR_SLICE_START_PTR(st->output->slices[st->header_idx]), type,
+  fill_header(
-              st->stream_id,
+      GPR_SLICE_START_PTR(st->output->slices[st->header_idx]), type,
-              st->output->length - st->output_length_at_start_of_frame,
+      st->stream_id, st->output->length - st->output_length_at_start_of_frame,
+      (gpr_uint8)(
           (is_last_in_stream ? GRPC_CHTTP2_DATA_FLAG_END_STREAM : 0) |
-                  (is_header_boundary ? GRPC_CHTTP2_DATA_FLAG_END_HEADERS : 0));
+          (is_header_boundary ? GRPC_CHTTP2_DATA_FLAG_END_HEADERS : 0)));
   st->cur_frame_type = NONE;
 }
 
@@ -190,6 +191,8 @@ static grpc_mdelem *add_elem(grpc_chttp2_hpack_compressor *c,
                      GPR_SLICE_LENGTH(elem->value->slice);
   grpc_mdelem *elem_to_unref;
 
+  GPR_ASSERT(elem_size < 65536);
+
   /* Reserve space for this element in the remote table: if this overflows
      the current table, drop elements until it fits, matching the decompressor
      algorithm */
@@ -201,14 +204,16 @@ static grpc_mdelem *add_elem(grpc_chttp2_hpack_compressor *c,
                c->table_elem_size[c->tail_remote_index %
                                   GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS]);
     GPR_ASSERT(c->table_elems > 0);
-    c->table_size -= c->table_elem_size[c->tail_remote_index %
+    c->table_size =
-                                        GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS];
+        (gpr_uint16)(c->table_size -
+                     c->table_elem_size[c->tail_remote_index %
+                                        GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS]);
     c->table_elems--;
   }
   GPR_ASSERT(c->table_elems < GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS);
   c->table_elem_size[new_index % GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS] =
-      elem_size;
+      (gpr_uint16)elem_size;
-  c->table_size += elem_size;
+  c->table_size = (gpr_uint16)(c->table_size + elem_size);
   c->table_elems++;
 
   /* Store this element into {entries,indices}_elem */
@@ -497,7 +502,7 @@ gpr_uint32 grpc_chttp2_preencode(grpc_stream_op *inops, size_t *inops_count,
   gpr_uint32 flow_controlled_bytes_taken = 0;
   gpr_uint32 curop = 0;
   gpr_uint8 *p;
-  int compressed_flag_set = 0;
+  gpr_uint8 compressed_flag_set = 0;
 
   while (curop < *inops_count) {
     GPR_ASSERT(flow_controlled_bytes_taken <= max_flow_controlled_bytes);
@@ -523,10 +528,10 @@ gpr_uint32 grpc_chttp2_preencode(grpc_stream_op *inops, size_t *inops_count,
 
         p = GPR_SLICE_START_PTR(slice);
         p[0] = compressed_flag_set;
-        p[1] = op->data.begin_message.length >> 24;
+        p[1] = (gpr_uint8)(op->data.begin_message.length >> 24);
-        p[2] = op->data.begin_message.length >> 16;
+        p[2] = (gpr_uint8)(op->data.begin_message.length >> 16);
-        p[3] = op->data.begin_message.length >> 8;
+        p[3] = (gpr_uint8)(op->data.begin_message.length >> 8);
-        p[4] = op->data.begin_message.length;
+        p[4] = (gpr_uint8)(op->data.begin_message.length);
         op->type = GRPC_OP_SLICE;
         op->data.slice = slice;
       /* fallthrough */
@@ -550,7 +555,7 @@ gpr_uint32 grpc_chttp2_preencode(grpc_stream_op *inops, size_t *inops_count,
           grpc_sopb_append(outops, op, 1);
           curop++;
         }
-        flow_controlled_bytes_taken += GPR_SLICE_LENGTH(slice);
+        flow_controlled_bytes_taken += (gpr_uint32)GPR_SLICE_LENGTH(slice);
         break;
     }
   }

src/core/transport/chttp2/varint.h

@@ -63,7 +63,7 @@ void grpc_chttp2_hpack_write_varint_tail(gpr_uint32 tail_value,
   do {                                                                        \
     gpr_uint8* tgt = target;                                                  \
     if ((length) == 1u) {                                                     \
-      (tgt)[0] = (prefix_or) | (n);                                           \
+      (tgt)[0] = (gpr_uint8)((prefix_or) | (n));                              \
     } else {                                                                  \
       (tgt)[0] = (prefix_or) | GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits);        \
       grpc_chttp2_hpack_write_varint_tail(                                    \

src/core/transport/chttp2_transport.c

@@ -209,7 +209,7 @@ static void ref_transport(grpc_chttp2_transport *t) { gpr_ref(&t->refs); }
 static void init_transport(grpc_chttp2_transport *t,
                            const grpc_channel_args *channel_args,
                            grpc_endpoint *ep, grpc_mdctx *mdctx,
-                           int is_client) {
+                           gpr_uint8 is_client) {
   size_t i;
   int j;
 
@@ -683,6 +683,8 @@ static void perform_stream_op_locked(
     stream_global->publish_sopb = op->recv_ops;
     stream_global->publish_sopb->nops = 0;
     stream_global->publish_state = op->recv_state;
+    /* clamp max recv bytes */
+    op->max_recv_bytes = GPR_MIN(op->max_recv_bytes, GPR_UINT32_MAX);
     if (stream_global->max_recv_bytes < op->max_recv_bytes) {
       GRPC_CHTTP2_FLOWCTL_TRACE_STREAM(
           "op", transport_global, stream_global, max_recv_bytes,
@@ -691,9 +693,8 @@ static void perform_stream_op_locked(
           "op", transport_global, stream_global, unannounced_incoming_window,
           op->max_recv_bytes - stream_global->max_recv_bytes);
       stream_global->unannounced_incoming_window +=
-          op->max_recv_bytes - stream_global->max_recv_bytes;
+          (gpr_uint32)op->max_recv_bytes - stream_global->max_recv_bytes;
-      stream_global->max_recv_bytes =
+      stream_global->max_recv_bytes = (gpr_uint32)op->max_recv_bytes;
-          (gpr_uint32)(GPR_MIN(op->max_recv_bytes, GPR_UINT32_MAX));
     }
     grpc_chttp2_incoming_metadata_live_op_buffer_end(
         &stream_global->outstanding_metadata);
@@ -730,14 +731,14 @@ static void send_ping_locked(grpc_chttp2_transport *t,
   p->next = &t->global.pings;
   p->prev = p->next->prev;
   p->prev->next = p->next->prev = p;
-  p->id[0] = (t->global.ping_counter >> 56) & 0xff;
+  p->id[0] = (gpr_uint8)((t->global.ping_counter >> 56) & 0xff);
-  p->id[1] = (t->global.ping_counter >> 48) & 0xff;
+  p->id[1] = (gpr_uint8)((t->global.ping_counter >> 48) & 0xff);
-  p->id[2] = (t->global.ping_counter >> 40) & 0xff;
+  p->id[2] = (gpr_uint8)((t->global.ping_counter >> 40) & 0xff);
-  p->id[3] = (t->global.ping_counter >> 32) & 0xff;
+  p->id[3] = (gpr_uint8)((t->global.ping_counter >> 32) & 0xff);
-  p->id[4] = (t->global.ping_counter >> 24) & 0xff;
+  p->id[4] = (gpr_uint8)((t->global.ping_counter >> 24) & 0xff);
-  p->id[5] = (t->global.ping_counter >> 16) & 0xff;
+  p->id[5] = (gpr_uint8)((t->global.ping_counter >> 16) & 0xff);
-  p->id[6] = (t->global.ping_counter >> 8) & 0xff;
+  p->id[6] = (gpr_uint8)((t->global.ping_counter >> 8) & 0xff);
-  p->id[7] = t->global.ping_counter & 0xff;
+  p->id[7] = (gpr_uint8)(t->global.ping_counter & 0xff);
   p->on_recv = on_recv;
   gpr_slice_buffer_add(&t->global.qbuf, grpc_chttp2_ping_create(0, p->id));
 }
@@ -999,7 +1000,7 @@ static void close_from_api(grpc_chttp2_transport_global *transport_global,
     *p++ = (gpr_uint8)('0' + (status % 10));
   }
   GPR_ASSERT(p == GPR_SLICE_END_PTR(status_hdr));
-  len += GPR_SLICE_LENGTH(status_hdr);
+  len += (gpr_uint32)GPR_SLICE_LENGTH(status_hdr);
 
   if (optional_message) {
     GPR_ASSERT(GPR_SLICE_LENGTH(*optional_message) < 127);
@@ -1019,23 +1020,23 @@ static void close_from_api(grpc_chttp2_transport_global *transport_global,
     *p++ = 'a';
     *p++ = 'g';
     *p++ = 'e';
-    *p++ = GPR_SLICE_LENGTH(*optional_message);
+    *p++ = (gpr_uint8)GPR_SLICE_LENGTH(*optional_message);
     GPR_ASSERT(p == GPR_SLICE_END_PTR(message_pfx));
-    len += GPR_SLICE_LENGTH(message_pfx);
+    len += (gpr_uint32)GPR_SLICE_LENGTH(message_pfx);
-    len += GPR_SLICE_LENGTH(*optional_message);
+    len += (gpr_uint32)GPR_SLICE_LENGTH(*optional_message);
   }
 
   hdr = gpr_slice_malloc(9);
   p = GPR_SLICE_START_PTR(hdr);
-  *p++ = len >> 16;
+  *p++ = (gpr_uint8)(len >> 16);
-  *p++ = len >> 8;
+  *p++ = (gpr_uint8)(len >> 8);
-  *p++ = len;
+  *p++ = (gpr_uint8)(len);
   *p++ = GRPC_CHTTP2_FRAME_HEADER;
   *p++ = GRPC_CHTTP2_DATA_FLAG_END_STREAM | GRPC_CHTTP2_DATA_FLAG_END_HEADERS;
-  *p++ = stream_global->id >> 24;
+  *p++ = (gpr_uint8)(stream_global->id >> 24);
-  *p++ = stream_global->id >> 16;
+  *p++ = (gpr_uint8)(stream_global->id >> 16);
-  *p++ = stream_global->id >> 8;
+  *p++ = (gpr_uint8)(stream_global->id >> 8);
-  *p++ = stream_global->id;
+  *p++ = (gpr_uint8)(stream_global->id);
   GPR_ASSERT(p == GPR_SLICE_END_PTR(hdr));
 
   gpr_slice_buffer_add(&transport_global->qbuf, hdr);
@@ -1281,7 +1282,7 @@ grpc_transport *grpc_create_chttp2_transport(
     const grpc_channel_args *channel_args, grpc_endpoint *ep, grpc_mdctx *mdctx,
     int is_client) {
   grpc_chttp2_transport *t = gpr_malloc(sizeof(grpc_chttp2_transport));
-  init_transport(t, channel_args, ep, mdctx, is_client);
+  init_transport(t, channel_args, ep, mdctx, is_client != 0);
   return &t->base;
 }
 

src/core/transport/metadata.c

@@ -334,7 +334,7 @@ grpc_mdstr *grpc_mdstr_from_string(grpc_mdctx *ctx, const char *str,
       grpc_mdstr *ret;
       for (i = 0; i < len; i++) {
         if (str[i] >= 'A' && str[i] <= 'Z') {
-          copy[i] = str[i] - 'A' + 'a';
+          copy[i] = (char)(str[i] - 'A' + 'a');
         } else {
           copy[i] = str[i];
         }
@@ -379,7 +379,7 @@ grpc_mdstr *grpc_mdstr_from_buffer(grpc_mdctx *ctx, const gpr_uint8 *buf,
     s->slice.refcount = NULL;
     memcpy(s->slice.data.inlined.bytes, buf, length);
     s->slice.data.inlined.bytes[length] = 0;
-    s->slice.data.inlined.length = length;
+    s->slice.data.inlined.length = (gpr_uint8)length;
   } else {
     /* string data goes after the internal_string header, and we +1 for null
        terminator */

templates/Makefile.template

@@ -247,10 +247,6 @@
   CXX11_CHECK_CMD = $(CXX) -std=c++11 -o $(TMPOUT) -c test/build/c++11.cc
   HAS_CXX11 = $(shell $(CXX11_CHECK_CMD) 2> /dev/null && echo true || echo false)
 
-  # Detect if -Wshorten-64-to-32 is a thing
-  SHORTEN_64_TO_32_CHECK_CMD = $(CC) -Wshorten-64-to-32 test/build/empty.c
-  HAS_SHORTEN_64_TO_32 = $(shell $(SHORTEN_64_TO_32_CHECK_CMD) 2> /dev/null && echo true || echo false)
-
   # The HOST compiler settings are used to compile the protoc plugins.
   # In most cases, you won't have to change anything, but if you are
   # cross-compiling, you can override these variables from GNU make's
@@ -265,10 +261,7 @@
   DEFINES += $(EXTRA_DEFINES)
   endif
 
-  CFLAGS += -std=c89 -pedantic -Wsign-conversion
+  CFLAGS += -std=c89 -pedantic -Wsign-conversion -Wconversion
-  ifeq ($(HAS_SHORTEN_64_TO_32),true)
-  CFLAGS += -Wshorten-64-to-32
-  endif
   ifeq ($(HAS_CXX11),true)
   CXXFLAGS += -std=c++11
   else

test/core/fling/client.c

@@ -130,7 +130,7 @@ static void step_ping_pong_stream(void) {
 
 static double now(void) {
   gpr_timespec tv = gpr_now(GPR_CLOCK_REALTIME);
-  return 1e9 * tv.tv_sec + tv.tv_nsec;
+  return 1e9 * (double)tv.tv_sec + tv.tv_nsec;
 }
 
 typedef struct {

test/core/iomgr/endpoint_tests.c

@@ -86,7 +86,7 @@ static grpc_endpoint_test_fixture begin_test(grpc_endpoint_test_config config,
 static void end_test(grpc_endpoint_test_config config) { config.clean_up(); }
 
 static gpr_slice *allocate_blocks(size_t num_bytes, size_t slice_size,
-                                  size_t *num_blocks, int *current_data) {
+                                  size_t *num_blocks, gpr_uint8 *current_data) {
   size_t nslices = num_bytes / slice_size + (num_bytes % slice_size ? 1 : 0);
   gpr_slice *slices = malloc(sizeof(gpr_slice) * nslices);
   size_t num_bytes_left = num_bytes;
@@ -102,7 +102,7 @@ static gpr_slice *allocate_blocks(size_t num_bytes, size_t slice_size,
     buf = GPR_SLICE_START_PTR(slices[i]);
     for (j = 0; j < GPR_SLICE_LENGTH(slices[i]); ++j) {
       buf[j] = *current_data;
-      *current_data = (*current_data + 1) % 256;
+      (*current_data)++;
     }
   }
   GPR_ASSERT(num_bytes_left == 0);
@@ -117,7 +117,7 @@ struct read_and_write_test_state {
   size_t current_write_size;
   size_t bytes_written;
   int current_read_data;
-  int current_write_data;
+  gpr_uint8 current_write_data;
   int read_done;
   int write_done;
   gpr_slice_buffer incoming;

test/core/iomgr/fd_posix_test.c

@@ -83,7 +83,8 @@ static void create_test_socket(int port, int *socket_fd,
   /* Use local address for test */
   sin->sin_family = AF_INET;
   sin->sin_addr.s_addr = htonl(0x7f000001);
-  sin->sin_port = htons(port);
+  GPR_ASSERT(port >= 0 && port < 65536);
+  sin->sin_port = htons((gpr_uint16)port);
 }
 
 /* Dummy gRPC callback */

test/core/iomgr/tcp_posix_test.c

@@ -81,7 +81,7 @@ static ssize_t fill_socket(int fd) {
   int i;
   unsigned char buf[256];
   for (i = 0; i < 256; ++i) {
-    buf[i] = i;
+    buf[i] = (gpr_uint8)i;
   }
   do {
     write_bytes = write(fd, buf, 256);
@@ -99,7 +99,7 @@ static size_t fill_socket_partial(int fd, size_t bytes) {
   unsigned char *buf = malloc(bytes);
   unsigned i;
   for (i = 0; i < bytes; ++i) {
-    buf[i] = i % 256;
+    buf[i] = (gpr_uint8)(i % 256);
   }
 
   do {
@@ -276,7 +276,7 @@ struct write_socket_state {
 };
 
 static gpr_slice *allocate_blocks(size_t num_bytes, size_t slice_size,
-                                  size_t *num_blocks, int *current_data) {
+                                  size_t *num_blocks, gpr_uint8 *current_data) {
   size_t nslices = num_bytes / slice_size + (num_bytes % slice_size ? 1u : 0u);
   gpr_slice *slices = gpr_malloc(sizeof(gpr_slice) * nslices);
   size_t num_bytes_left = num_bytes;
@@ -291,7 +291,7 @@ static gpr_slice *allocate_blocks(size_t num_bytes, size_t slice_size,
     buf = GPR_SLICE_START_PTR(slices[i]);
     for (j = 0; j < GPR_SLICE_LENGTH(slices[i]); ++j) {
       buf[j] = *current_data;
-      *current_data = (*current_data + 1) % 256;
+      (*current_data)++;
     }
   }
   GPR_ASSERT(num_bytes_left == 0);
@@ -373,7 +373,7 @@ static void write_test(size_t num_bytes, size_t slice_size) {
   ssize_t read_bytes;
   size_t num_blocks;
   gpr_slice *slices;
-  int current_data = 0;
+  gpr_uint8 current_data = 0;
   gpr_slice_buffer outgoing;
   grpc_iomgr_closure write_done_closure;
   gpr_timespec deadline = GRPC_TIMEOUT_SECONDS_TO_DEADLINE(20);

test/core/iomgr/udp_server_test.c

@@ -59,7 +59,7 @@ static void on_read(int fd, grpc_udp_server_cb new_transport_cb, void *cb_arg) {
   byte_count = recv(fd, read_buffer, sizeof(read_buffer), 0);
 
   g_number_of_reads++;
-  g_number_of_bytes_read += byte_count;
+  g_number_of_bytes_read += (int)byte_count;
 
   grpc_pollset_kick(&g_pollset, NULL);
   gpr_mu_unlock(GRPC_POLLSET_MU(&g_pollset));

test/core/json/json_rewrite.c

@@ -34,8 +34,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include <grpc/support/cmdline.h>
 #include <grpc/support/alloc.h>
+#include <grpc/support/cmdline.h>
+#include <grpc/support/log.h>
 
 #include "src/core/json/json_reader.h"
 #include "src/core/json/json_writer.h"
@@ -96,7 +97,8 @@ static void json_reader_string_clear(void* userdata) {
 static void json_reader_string_add_char(void* userdata, gpr_uint32 c) {
   json_reader_userdata* state = userdata;
   check_string(state, 1);
-  state->scratchpad[state->string_len++] = c;
+  GPR_ASSERT(c < 256);
+  state->scratchpad[state->string_len++] = (char)c;
 }
 
 static void json_reader_string_add_utf32(void* userdata, gpr_uint32 c) {

test/core/json/json_rewrite_test.c

@@ -108,7 +108,8 @@ static void json_reader_string_clear(void* userdata) {
 static void json_reader_string_add_char(void* userdata, gpr_uint32 c) {
   json_reader_userdata* state = userdata;
   check_string(state, 1);
-  state->scratchpad[state->string_len++] = c;
+  GPR_ASSERT(c <= 256);
+  state->scratchpad[state->string_len++] = (char)c;
 }
 
 static void json_reader_string_add_utf32(void* userdata, gpr_uint32 c) {

test/core/support/slice_test.c

@@ -116,7 +116,7 @@ static void test_slice_sub_works(unsigned length) {
      beginning of the slice. */
   slice = gpr_slice_malloc(length);
   for (i = 0; i < length; i++) {
-    GPR_SLICE_START_PTR(slice)[i] = i;
+    GPR_SLICE_START_PTR(slice)[i] = (gpr_uint8)i;
   }
 
   /* Ensure that for all subsets length is correct and that we start on the
@@ -155,7 +155,7 @@ static void test_slice_split_head_works(size_t length) {
      beginning of the slice. */
   slice = gpr_slice_malloc(length);
   for (i = 0; i < length; i++) {
-    GPR_SLICE_START_PTR(slice)[i] = i;
+    GPR_SLICE_START_PTR(slice)[i] = (gpr_uint8)i;
   }
 
   /* Ensure that for all subsets length is correct and that we start on the
@@ -183,7 +183,7 @@ static void test_slice_split_tail_works(size_t length) {
      beginning of the slice. */
   slice = gpr_slice_malloc(length);
   for (i = 0; i < length; i++) {
-    GPR_SLICE_START_PTR(slice)[i] = i;
+    GPR_SLICE_START_PTR(slice)[i] = (gpr_uint8)i;
   }
 
   /* Ensure that for all subsets length is correct and that we start on the

test/core/transport/chttp2/stream_encoder_test.c

@@ -59,7 +59,7 @@ static gpr_slice create_test_slice(size_t length) {
   gpr_slice slice = gpr_slice_malloc(length);
   size_t i;
   for (i = 0; i < length; i++) {
-    GPR_SLICE_START_PTR(slice)[i] = i;
+    GPR_SLICE_START_PTR(slice)[i] = (gpr_uint8)i;
   }
   return slice;
 }
@@ -196,10 +196,10 @@ static void test_basic_headers(void) {
 }
 
 static void encode_int_to_str(int i, char *p) {
-  p[0] = 'a' + i % 26;
+  p[0] = (char)('a' + i % 26);
   i /= 26;
   GPR_ASSERT(i < 26);
-  p[1] = 'a' + i;
+  p[1] = (char)('a' + i);
   p[2] = 0;
 }
 
@@ -246,7 +246,7 @@ static void randstr(char *p, int bufsz) {
   int i;
   int len = 1 + rand() % bufsz;
   for (i = 0; i < len; i++) {
-    p[i] = 'a' + rand() % 26;
+    p[i] = (char)('a' + rand() % 26);
   }
   p[len] = 0;
 }

test/core/util/parse_hexstring.c

@@ -54,10 +54,10 @@ gpr_slice parse_hexstring(const char *hexstring) {
   temp = 0;
   for (p = hexstring; *p; p++) {
     if (*p >= '0' && *p <= '9') {
-      temp = (temp << 4) | (*p - '0');
+      temp = (gpr_uint8)(temp << 4) | (gpr_uint8)(*p - '0');
       nibbles++;
     } else if (*p >= 'a' && *p <= 'f') {
-      temp = (temp << 4) | (*p - 'a' + 10);
+      temp = (gpr_uint8)(temp << 4) | (gpr_uint8)(*p - 'a' + 10);
       nibbles++;
     }
     if (nibbles == 2) {

test/core/util/port_posix.c

@@ -102,7 +102,7 @@ static int is_port_available(int *port, int is_tcp) {
   /* Try binding to port */
   addr.sin_family = AF_INET;
   addr.sin_addr.s_addr = INADDR_ANY;
-  addr.sin_port = htons(*port);
+  addr.sin_port = htons((gpr_uint16)*port);
   if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
     gpr_log(GPR_DEBUG, "bind(port=%d) failed: %s", *port, strerror(errno));
     close(fd);

test/core/util/reconnect_server.c

@@ -116,7 +116,7 @@ void reconnect_server_start(reconnect_server *server, int port) {
   int port_added;
 
   addr.sin_family = AF_INET;
-  addr.sin_port = htons(port);
+  addr.sin_port = htons((gpr_uint16)port);
   memset(&addr.sin_addr, 0, sizeof(addr.sin_addr));
 
   server->tcp_server = grpc_tcp_server_create();

test/core/util/test_config.h

@@ -55,13 +55,15 @@ extern double g_fixture_slowdown_factor;
    g_fixture_slowdown_factor)
 
 #define GRPC_TIMEOUT_SECONDS_TO_DEADLINE(x)                               \
-  gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC),                               \
+  gpr_time_add(                                                           \
-               gpr_time_from_millis(GRPC_TEST_SLOWDOWN_FACTOR * 1e3 * (x), \
+      gpr_now(GPR_CLOCK_MONOTONIC),                                       \
+      gpr_time_from_millis((long)(GRPC_TEST_SLOWDOWN_FACTOR * 1e3 * (x)), \
                            GPR_TIMESPAN))
 
 #define GRPC_TIMEOUT_MILLIS_TO_DEADLINE(x)                                \
-  gpr_time_add(gpr_now(GPR_CLOCK_MONOTONIC),                               \
+  gpr_time_add(                                                           \
-               gpr_time_from_micros(GRPC_TEST_SLOWDOWN_FACTOR * 1e3 * (x), \
+      gpr_now(GPR_CLOCK_MONOTONIC),                                       \
+      gpr_time_from_micros((long)(GRPC_TEST_SLOWDOWN_FACTOR * 1e3 * (x)), \
                            GPR_TIMESPAN))
 
 #ifndef GRPC_TEST_CUSTOM_PICK_PORT

tools/codegen/core/gen_hpack_tables.c

@@ -71,13 +71,13 @@ static unsigned char prefix_mask(unsigned char prefix_len) {
   unsigned char i;
   unsigned char out = 0;
   for (i = 0; i < prefix_len; i++) {
-    out |= 1 << (7 - i);
+    out |= (unsigned char)(1 << (7 - i));
   }
   return out;
 }
 
 static unsigned char suffix_mask(unsigned char prefix_len) {
-  return ~prefix_mask(prefix_len);
+  return (unsigned char)~prefix_mask(prefix_len);
 }
 
 static void generate_first_byte_lut(void) {
@@ -92,7 +92,7 @@ static void generate_first_byte_lut(void) {
     chrspec = NULL;
     for (j = 0; j < num_fields; j++) {
       if ((prefix_mask(fields[j].prefix_length) & i) == fields[j].prefix) {
-        suffix = suffix_mask(fields[j].prefix_length) & i;
+        suffix = suffix_mask(fields[j].prefix_length) & (unsigned char)i;
         if (suffix == suffix_mask(fields[j].prefix_length)) {
           if (fields[j].index != 2) continue;
         } else if (suffix == 0) {
@@ -336,7 +336,7 @@ static void generate_base64_inverse_table(void) {
 
   memset(inverse, 255, sizeof(inverse));
   for (i = 0; i < strlen(alphabet); i++) {
-    inverse[(unsigned char)alphabet[i]] = i;
+    inverse[(unsigned char)alphabet[i]] = (unsigned char)i;
   }
 
   printf("static const gpr_uint8 inverse_base64[256] = {");

tools/codegen/core/gen_legal_metadata_characters.c

@@ -41,7 +41,7 @@ static unsigned char legal_bits[256 / 8];
 static void legal(int x) {
   int byte = x / 8;
   int bit = x % 8;
-  legal_bits[byte] |= 1 << bit;
+  legal_bits[byte] |= (unsigned char)(1 << bit);
 }
 
 static void dump(void) {