Merge pull request #380 from Dmitry-Me/getRidOfWtypeLimits

Get rid of -Wtype-limits warning

tinyxml2.cpp

@@ -1914,6 +1914,26 @@ XMLError XMLDocument::LoadFile( const char* filename )
     return _errorID;
 }
 
+// This is likely overengineered template art to have a check that unsigned long value incremented
+// by one still fits into size_t. If size_t type is larger than unsigned long type
+// (x86_64-w64-mingw32 target) then the check is redundant and gcc and clang emit
+// -Wtype-limits warning. This piece makes the compiler select code with a check when a check
+// is useful and code with no check when a check is redundant depending on how size_t and unsigned long
+// types sizes relate to each other.
+template
+<bool = (sizeof(unsigned long) >= sizeof(size_t))>
+struct LongFitsIntoSizeTMinusOne {
+    static bool Fits( unsigned long value )
+    {
+        return value < (size_t)-1;
+    }
+};
+
+template <>
+bool LongFitsIntoSizeTMinusOne<false>::Fits( unsigned long /*value*/ )
+{
+    return true;
+}
 
 XMLError XMLDocument::LoadFile( FILE* fp )
 {
@@ -1933,7 +1953,7 @@ XMLError XMLDocument::LoadFile( FILE* fp )
         return _errorID;
     }
 
-    if ( (unsigned long)filelength >= (size_t)-1 ) {
+    if ( !LongFitsIntoSizeTMinusOne<>::Fits( filelength ) ) {
         // Cannot handle files which won't fit in buffer together with null terminator
         SetError( XML_ERROR_FILE_READ_ERROR, 0, 0 );
         return _errorID;