I saw following warnings when I compiled HotSpot with GCC 9 on Fedora 30:


/home/ysuenaga/OpenJDK/jdk/src/hotspot/os/linux/osContainer_linux.cpp: In static member function 'static jlong OSContainer::memory_limit_in_bytes()':
/home/ysuenaga/OpenJDK/jdk/src/hotspot/os/linux/osContainer_linux.cpp:470:22: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
  470 | char* format = "%s " JULONG_FORMAT;

/home/ysuenaga/OpenJDK/jdk/src/hotspot/os/linux/osContainer_linux.cpp: In static member function 'static jlong OSContainer::memory_and_swap_limit_in_bytes()':
/home/ysuenaga/OpenJDK/jdk/src/hotspot/os/linux/osContainer_linux.cpp:493:22: warning: deprecated conversion from string constant to 'char*' [-Wwrite-strings]
  493 | char* format = "%s " JULONG_FORMAT;

/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/gc/shared/ptrQueue.cpp: In constructor 'BufferNode::Allocator::Allocator(const char*, size_t)':
/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/gc/shared/ptrQueue.cpp:97:10: warning: 'char* strncpy(char*, const char*, size_t)' specified bound 120 equals destination size [-Wstringop-truncation]
   97 | strncpy(_name, name, sizeof(_name));
      | ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/compiler/disassembler.cpp: In constructor 'decode_env::decode_env(CodeBlob*, outputStream*, CodeStrings, ptrdiff_t)':
/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/compiler/disassembler.cpp:365:32: warning: 'void* memset(void*, int, size_t)' clearing an object of non-trivial type 'class decode_env'; use assignment instead [-Wclass-memaccess]
  365 | memset(this, 0, sizeof(*this)); // Beware, this zeroes bits of fields.
      | ^
/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/compiler/disassembler.cpp:153:7: note: 'class decode_env' declared here
  153 | class decode_env {
      | ^~~~~~~~~~

In file included from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/runtime/thread.hpp:34,
                 from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/runtime/safepoint.hpp:30,
                 from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/gc/shared/collectedHeap.hpp:33,
                 from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/precompiled/precompiled.hpp:37:
In constructor 'JvmtiCodeBlobDesc::JvmtiCodeBlobDesc(const char*, address, address)',
    inlined from 'static void CodeBlobCollector::do_blob(CodeBlob*)' at /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/prims/jvmtiCodeBlobEvents.cpp:141:94:
/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/prims/jvmtiExport.hpp:423:12: warning: 'char* strncpy(char*, const char*, size_t)' specified bound 64 equals destination size [-Wstringop-truncation]
  423 | strncpy(_name, name, sizeof(_name));
      | ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In constructor 'JvmtiCodeBlobDesc::JvmtiCodeBlobDesc(const char*, address, address)',
    inlined from 'void CodeBlobCollector::collect()' at /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/prims/jvmtiCodeBlobEvents.cpp:177:94:
/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/prims/jvmtiExport.hpp:423:12: warning: 'char* strncpy(char*, const char*, size_t)' specified bound 64 equals destination size [-Wstringop-truncation]
  423 | strncpy(_name, name, sizeof(_name));
      | ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~

In file included from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/runtime/thread.hpp:34,
                 from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/runtime/safepoint.hpp:30,
                 from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/gc/shared/collectedHeap.hpp:33,
                 from /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/precompiled/precompiled.hpp:37:
In constructor 'JvmtiCodeBlobDesc::JvmtiCodeBlobDesc(const char*, address, address)',
    inlined from 'void JvmtiDynamicCodeEventCollector::register_stub(const char*, address, address)' at /home/ysuenaga/OpenJDK/jdk/src/hotspot/share/prims/jvmtiExport.cpp:2825:60:
/home/ysuenaga/OpenJDK/jdk/src/hotspot/share/prims/jvmtiExport.hpp:423:12: warning: 'char* strncpy(char*, const char*, size_t)' specified bound 64 equals destination size [-Wstringop-truncation]
  423 | strncpy(_name, name, sizeof(_name));
      |