Make TokuDB compile with GCC-8

GCC-8 introduced multiple warnings and increased the level of
strictness.

* -Wshadow will warn if a local variable shadows a typedef.
* GCC will also warn when memsetting a non-trivial type.
  In this case a non-trivial type can not have a custom constructor.
  For all intents and purposes, the class is trivially-copyable.
* GCC will also warn if you use too many paranthesses which are not
necessary

storage/tokudb/CMakeLists.txt

@@ -17,6 +17,12 @@ IF(NOT LIBJEMALLOC)
   MESSAGE(WARNING "TokuDB is enabled, but jemalloc is not. This configuration is not supported")
 ENDIF()
 
+CHECK_C_COMPILER_FLAG("-Wshadow" HAVE_WSHADOW)
+IF (HAVE_WSHADOW)
+  SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-shadow")
+  SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-shadow")
+ENDIF()
+
 IF (HAVE_WVLA)
   SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-vla")
   SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-vla")

storage/tokudb/ft-index/portability/memory.h

@@ -160,7 +160,7 @@ size_t toku_malloc_usable_size(void *p) __attribute__((__visibility__("default")
 #define XMALLOC(v) CAST_FROM_VOIDP(v, toku_xmalloc(sizeof(*v)))
 #define XMALLOC_N(n,v) CAST_FROM_VOIDP(v, toku_xmalloc((n)*sizeof(*v)))
 #define XCALLOC_N(n,v) CAST_FROM_VOIDP(v, toku_xcalloc((n), (sizeof(*v))))
-#define XCALLOC(v) XCALLOC_N(1,(v))
+#define XCALLOC(v) XCALLOC_N(1,v)
 #define XREALLOC(v,s) CAST_FROM_VOIDP(v, toku_xrealloc(v, s))
 #define XREALLOC_N(n,v) CAST_FROM_VOIDP(v, toku_xrealloc(v, (n)*sizeof(*v)))
 

storage/tokudb/ft-index/tools/ba_replay.cc

@@ -638,7 +638,7 @@ int main(int argc, char *argv[]) {
                                    it == candidate_strategies.begin() ? &stats : &dummy_stats);
 
         struct fragmentation_report aggregate_report;
-        memset(&aggregate_report, 0, sizeof(aggregate_report));
+        memset(static_cast<void *>(&aggregate_report), 0, sizeof(aggregate_report));
         for (map<uint64_t, struct fragmentation_report>::iterator rp = reports.begin();
              rp != reports.end(); rp++) {
             const struct fragmentation_report &report = rp->second;

storage/tokudb/ft-index/util/dmt.cc

@@ -132,8 +132,8 @@ void dmt<dmtdata_t, dmtdataout_t, dmtwriter_t>::create_from_sorted_memory_of_fix
         paranoid_invariant(numvalues > 0);
         void *ptr = toku_mempool_malloc(&this->mp, aligned_memsize);
         paranoid_invariant_notnull(ptr);
-        uint8_t * const CAST_FROM_VOIDP(dest, ptr);
-        const uint8_t * const CAST_FROM_VOIDP(src, mem);
+        uint8_t * CAST_FROM_VOIDP(dest, ptr);
+        const uint8_t * CAST_FROM_VOIDP(src, mem);
         if (pad_bytes == 0) {
             paranoid_invariant(aligned_memsize == mem_length);
             memcpy(dest, src, aligned_memsize);