Warning-related tweaks.

c++/src/capnproto/common.h

@@ -48,7 +48,7 @@ inline T& operator<<(T& os, Void) { return os << "void"; }
 
 using kj::byte;
 
-class word { uint64_t content KJ_UNUSED_FOR_CLANG; KJ_DISALLOW_COPY(word); public: word() = default; };
+class word { uint64_t content KJ_UNUSED_MEMBER; KJ_DISALLOW_COPY(word); public: word() = default; };
 // word is an opaque type with size of 64 bits.  This type is useful only to make pointer
 // arithmetic clearer.  Since the contents are private, the only way to access them is to first
 // reinterpret_cast to some other pointer type.

c++/src/kj/common.h

@@ -104,11 +104,11 @@ typedef unsigned char byte;
 #define KJ_UNUSED __attribute__((unused));
 
 #if __clang__
-#define KJ_UNUSED_FOR_CLANG __attribute__((unused));
-// Clang reports "unused" warnings in some places where GCC does not even allow the "unused"
-// attribute.
+#define KJ_UNUSED_MEMBER __attribute__((unused));
+// Inhibits "unused" warning for member variables.  Only Clang produces such a warning, while GCC
+// complains if the attribute is set on members.
 #else
-#define KJ_UNUSED_FOR_CLANG
+#define KJ_UNUSED_MEMBER
 #endif
 
 namespace internal {

c++/src/kj/exception.c++

@@ -44,7 +44,7 @@ String getStackSymbols(ArrayPtr<void* const> trace) {
 
   char exe[512];
   ssize_t n = readlink("/proc/self/exe", exe, sizeof(exe));
-  if (n < 0 || n >= sizeof(exe)) {
+  if (n < 0 || n >= static_cast<ssize_t>(sizeof(exe))) {
     return nullptr;
   }
   exe[n] = '\0';