Fix gcc compilation

src/core/transport/chttp2/varint.h

@@ -50,7 +50,8 @@ void grpc_chttp2_hpack_write_varint_tail(gpr_uint32 tail_value,
 /* maximum value that can be bitpacked with the opcode if the opcode has a
    prefix
    of length prefix_bits */
-#define GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) ((1 << (8 - (prefix_bits))) - 1)
+#define GRPC_CHTTP2_MAX_IN_PREFIX(prefix_bits) \
+  ((gpr_uint32)((1 << (8 - (prefix_bits))) - 1))
 
 /* length required to bitpack a value */
 #define GRPC_CHTTP2_VARINT_LENGTH(n, prefix_bits) \

test/core/transport/chttp2/varint_test.c

@@ -38,7 +38,9 @@
 
 #include "test/core/util/test_config.h"
 
-static void test_varint(gpr_uint32 value, int prefix_bits, gpr_uint8 prefix_or, const char *expect_bytes, size_t expect_length) {
+static void test_varint(gpr_uint32 value, gpr_uint32 prefix_bits,
+                        gpr_uint8 prefix_or, const char *expect_bytes,
+                        size_t expect_length) {
   gpr_uint32 nbytes = GRPC_CHTTP2_VARINT_LENGTH(value, prefix_bits);
   gpr_slice expect = gpr_slice_from_copied_buffer(expect_bytes, expect_length);
   gpr_slice slice;