[THRIFT-4846] C++ generator should topologically sort struct definitions and error on cycles

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: C++ - Compiler
• Patch Info: Patch Available
• Assignee: Todd Lipcon
• Reporter: Todd Lipcon
• Created: 05/Apr/19 18:56
• Updated: 18/Mar/20 12:51

Description

C++ (and maybe other languages?) treat Thrift struct-typed fields as plain struct members of the containing struct. Currently, the generator outputs the types in the same order as they're defined in the underlying Thrift field, which means that a file like:

struct A {
  1: B foo;
}
struct B {
}

will generate C++ code that fails to compile.

We should topologically-sort the structs before outputting the definitions so that the generated code compiles correctly.

Issue Links

• is related to: HIVE-21586 Thrift generated cpp files for metastore do not compile
• links to: GitHub Pull Request #1786