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## Bug
A bare `except:` followed by a `finally:` block raises a spurious
`ReraiseDefect: no exception to reraise` when compiled with `nim cpp`:
```nim
proc test() =
try:
raise newException(CatchableError, "x")
except:
discard
finally:
echo "finally"
test()
echo "after"
```
Expected output:
```
finally
after
```
Actual output:
```
finally
fatal.nim(53) sysFatal
Error: unhandled exception: no exception to reraise [ReraiseDefect]
```
This reproduces on every memory manager (`--mm:arc`, `--mm:orc`,
`--mm:refc`).
## Root cause
`genTryCpp` emits `try { ... } catch (Exception* T_) { ... }` followed
by a finally block that ends with `if (T_) std::rethrow_exception(T_);`.
In the *typed* except branches the codegen explicitly sets `T_ =
nullptr;` once the exception is handled, so the rethrow check in the
finally is a no-op.
The typeless `except:` branch (the `if t[i].len == 1` arm) emitted only
`popCurrentException()` and forgot to clear `T_`. After the handler body
finished, `T_` still pointed at the original exception, so the trailing
`if (T_) std::rethrow_exception(T_);` rethrew it. By that point Nim's
current-exception stack had already been popped, and the rethrow
surfaced as `ReraiseDefect`.
## Fix
Emit `T_ = nullptr;` at the start of the typeless `except:` handler
body, mirroring what is already done for the typed branches. This is the
same one-line treatment that fixed the analogous typed-except case for
#5871.
## Tests
Adds `tests/exception/treraise_typeless_except_finally.nim`, exercising
the bug pattern on `--mm:arc`, `--mm:orc`, and `--mm:refc`.
Locally:
- `tests/exception/` — 43 PASS, 0 FAIL, 3 SKIP
- new test passes on all three memory managers
## Backport
Tagged `[backport]` in the commit message — the same bug exists in
`version-2-2` and the fix applies cleanly there.
## Related
Independent of, but in the same family as, #25775 (also currently open).
Both are silent-finally / cpp-backend exception handling fixes; they
touch different lines of `genTryCpp` and don't conflict.
Co-authored-by: puffball1567 <17452514+puffball1567@users.noreply.github.com>