Add comment on INT64_MIN edge case

Author: fairywreath

source/slang/slang-parser.cpp

@@ -6678,6 +6678,13 @@ static BaseType _determineNonSuffixedIntegerLiteralType(
 
         if (isDecimalBase)
         {
+            // There is an edge case here where 9223372036854775808 or INT64_MAX + 1
+            // brings us here, but the complete literal is -9223372036854775808 or INT64_MIN and is valid.
+            // Unfortunately because the lexer handles the negative(-) part of the literal separately
+            // it is impossible to know whether the literal has a negative sign or not.
+            // We emit the warning and initially process it as a uint64 anyways, and the negative sign
+            // will be properly parsed and the value will still be properly stored as a negative INT64_MIN.
+
             // Decimal integer is too large to be represented as signed.
             // Output warning that it is represented as unsigned instead.
             sink->diagnose(