Fix rest c4018 warnings

Author: Artyom Abakumov

src/burp/restore.epp

@@ -12365,7 +12365,7 @@ bool RestoreRelationTask::fileReader(Item& item)
 		const FB_SSIZE_T attLen = 1 + (tdgbl->gbl_sw_transportable ? 12 : 6);
 		const FB_SSIZE_T overhead = tdgbl->gbl_sw_compress ? (len / 127 + 1) : 0;
 
-		if (len + attLen + overhead > space)
+		if (static_cast<FB_SSIZE_T>(len) + attLen + overhead > space)
 		{
 			if (ioBuf)
 			{

src/jrd/inf.cpp

@@ -785,7 +785,7 @@ void INF_database_info(thread_db* tdbb,
 					length = gds__vax_integer(items, 2);
 					items += 2;
 
-					if (end_items - items >= length)
+					if (static_cast<ULONG>(end_items - items) >= length)
 					{
 						pageNum = gds__vax_integer(items, length);
 						items += length;

src/jrd/sqz.cpp

@@ -558,7 +558,7 @@ ULONG Difference::apply(ULONG diffLength, ULONG outLength, UCHAR* const output)
 			BUGCHECK(177);	// msg 177 applied differences will not fit in record
 	}
 
-	const auto length = p - output;
+	const FB_UINT64 length = p - output;
 
 	if (length > outLength)
 		BUGCHECK(177);	// msg 177 applied differences will not fit in record

src/yvalve/why.cpp

@@ -1424,7 +1424,7 @@ static void setTextType(XSQLVAR* var, unsigned charSet)
 static int sqldaTruncateString(char* buffer, FB_SIZE_T size, const char* s)
 {
 	int ret = fb_utils::snprintf(buffer, size, "%s", s);
-	return MIN(ret, size - 1);
+	return MIN(ret, static_cast<int>(size - 1));
 }
 
 // Describe parameters metadata in an sqlda.