[ASDAlexander77]

An empty catch clause did not catch anything. This program died with tslang: error: uncaught exception under every -mm:

function h() { throw 1; }
function k() { try { h(); } catch { } }
function main() { k(); print("end"); }

Cause. An untyped catch { } puts no ops in the TryOp's catches region. TryOpLowering set catchHasOps from whether that region held anything besides its terminator. So it treated the empty catch as "no catch clause", which is what the TryOps that only wrap a scope for its cleanup look like. It made no landing pad, and the exception went uncaught.

Fix. mlirGen(TryStatement) now marks a TryOp that has a catch clause with a HAS_CATCH_ATTR_NAME unit attribute. TryOpLowering treats a marked TryOp as having a catch even when the region is empty. The cleanup-only TryOps (block/using wraps) stay unmarked, so for them an empty region still means "no catch".

Test. 00try_empty_catch.ts covers:

• an empty catch { }, catch (e) { } and catch { ; }
• an empty catch followed by finally
• an owned local in the try
• nested empty catches
• an empty catch in a loop
• a try that does not throw
• an empty catch in a method

It is registered for compile, JIT and TSLANG_CORPUS.

The repro prints "end" under gc, rc, none and own. Full ctest -C Release -j 8 --timeout 300 passes: 4138 tests, 0 failures.

Found while working on #596.

🤖 Generated with Claude Code