[perfloop-agent]

Unlabelled breaks inside nested control-flow macros now reach their intended targets rather than a generated loop. The rewriters inspect nested macro inputs before those inputs expand.

• Reuse the nested-macro walker for goto jumps and exit rewriting.
• Treat nested goto blocks as transparent, while each switch owns breaks in its arms.
• Visit nested switch conditions and guards in the enclosing context.

Real user loops still stop propagation, and explicitly labelled exits are unchanged. Traversal recognizes macros named goto_block! and switch!, including qualified paths; other macro token bodies remain opaque.

Testing

tests/unit/goto_nested_loop_control.c checks nested labelled compounds in a user loop and in a fallthrough switch. The switch version checks that a break leaves the switch while later user-loop iterations still run. Lit compares native C with both translation models and checks their generated-source expectations.

The macro test runner reports 23 passed, no failures and no ignored tests, covering dispatch, fallthrough, goto jumps and the compile-fail harness. The existing Rust tests are unchanged.

Coverage is bounded; affected application prevalence remains unknown.

5 recorded checks pass with this change.

• libcc2rs-macros unit, integration and compile-fail tests
• libcc2rs-macros rustfmt
• libcc2rs-macros clippy
• Nested control-flow C fixture clang-format
• Goto and switch lit tests in both translation models

Case and evidence

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Made by Perfloop. Human sponsor: Tomás Senart.

[nunoplopes]

@perfloop-agent Instead of having this complicated test in control_flow.rs, extend the C test (goto_nested_loop_control.c) to have a version with switch to cover the new code.

[perfloop-agent]

I removed the added Rust tests and extended the C fixture with a switch version. It nests labelled compounds inside a fallthrough switch and checks that break leaves the switch while the user loop continues.