Was playing around manually modifying the Table in one package and was surprised to find out that it causes CRC32 errors in another package.

The name MakeTable seems to indicate that a unique table will be created and returned. But for the IEEE and Castagnoli polynomials specifically, it returns a reference to tables held globally. This has the following consequences:

• Modifying a table returned by MakeTable(IEEE), may or may not cause all CRCs that use the IEEE polynomial to be incorrect. This is because there are special cases where it uses a special iEEETable8 if the input table is a pointer match to IEEETable.
• Modifying a table returned by MakeTable(Castagnoli) may or may not cause other Castagnoli polynomials to be wrong. This is because if the input table is a pointer match to castagnoliTable and the hardware support CRC instructions, it will use the built in instructions or table. Either way, the behavior is very confusing.
• Modifying a table returned by MakeTable for any other polynomial works as expected.

See https://play.golang.org/p/IWehs0lQAc