[jira] [Created] (THRIFT-6062) Smalltalk compiler crashes (stack overflow) on recursive struct types

["Jens Geyer (Jira)" <ji...@apache.org>]

Jens Geyer created THRIFT-6062:
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             Summary: Smalltalk compiler crashes (stack overflow) on recursive struct types
                 Key: THRIFT-6062
                 URL: https://issues.apache.org/jira/browse/THRIFT-6062
             Project: Thrift
          Issue Type: Bug
          Components: Smalltalk - Compiler
    Affects Versions: 0.24.0
            Reporter: Jens Geyer


The Smalltalk generator inline-expands nested struct (de)serialization: when generating the read/write code for a struct-typed field, {{write_val}} / {{read_val}} emit {{struct_writer}} / {{struct_reader}} for the field's type *inline* (compiler/cpp/src/thrift/generate/t_st_generator.cc). There is no base case or visited-set guard for this expansion, so a self- or mutually-recursive struct type makes the generator recurse until the C++ call stack overflows, crashing with SIGSEGV.

Struct read/write code is only emitted inside service send/recv methods, so the crash occurs when a recursive type is reachable from a service.

h3. Reproduction

Minimal self-recursive type:

{code}
struct RecTree { 1: list<RecTree> children, 2: i16 item }
service S { RecTree echo(1: RecTree t) }
{code}

{code}
$ thrift --gen st recur.thrift
Segmentation fault (core dumped)
{code}

Mutually recursive types ({{CoRec}} / {{CoRec2}}) crash the same way, as does test/Recursive.thrift. A finite, non-recursive chain of distinct struct types generates correctly, so the trigger is specifically type recursion (not depth alone).

h3. Notes

* Reproduced with the 0.24.0 compiler.
* This is a separate, pre-existing limitation surfaced while adding a runtime recursion-depth limit to the Smalltalk library (THRIFT-6052): because recursive types cannot be generated at all, that limit can currently only be exercised through a finite chain of distinct struct types.
* A fix would bound or restructure the inline expansion, e.g. emit per-struct read/write helper methods and call them, rather than textually inlining nested struct serialization.




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