[Jens-G]

THRIFT-6493

With the union option, each member class of a generated union compared only the values in Equals, against other.As_<member>. That property returns the default value when another member is set. So U.x(0).Equals(U.y(0)) was true, and U.x(0).Equals(U.s("text")) was true while the reverse was false. GetHashCode() ignored the member as well.

Changes

• t_netstd_generator.cc:
  • the Equals of the member classes first checks which member is set, as the base class already does;
  • their GetHashCode() adds the member's field ID before the value, and the base class computes the same value. This applies to both the net and the netstandard code path.
• Thrift6493.thrift, added to the four Thrift.Compile projects, and DataModel/UnionEquality.cs. The tests cover:
  • equality across members, and the asymmetric pair;
  • hashing across members, and a HashSet;
  • equal values still hashing equally.

Compatibility

Union values of different members that hold equal values are no longer equal, and the hash codes of union values change.

Verification

• With the master compiler, 4 of the 5 tests fail:
  • Assert.IsFalse(new U.x(0).Equals(new U.y(0))) gets true;
  • x(5) and y(5) both hash to 5;
  • a HashSet keeps only 4 of 5 values.
• With the fix all 5 pass.
• Thrift.Tests passes 157 of 157, IntegrationTests 57 of 57, and the compiler tests pass.
• Over the test IDLs, only the generated code of unions changes.

This is the union counterpart of THRIFT-5056 (#4104), which covers structs. The two PRs change different generator code and merge in either order.

🤖 Generated with Claude Code