tool/cpp_front.py is a second front end written against the state model,
not the rules: it reads a compile database with libclang (Homebrew LLVM)
and writes the JSON that `pipe check --model` takes. Every rule,
baseline and gate works on it unchanged.
Mapping, per project `enum class` (identity from clang's resolved AST,
so two enums both named QueryIntent are never confused):
- a reference that produces a value (assignment, atomic store, argument,
return, initialiser) is an emission; a cast from an int is an indirect
one;
- a `case`, `==` or `!=` is an observation;
- a busy enumerator written to the method's OWN state, followed by a
top-level try whose catch neither writes state nor rethrows, is a
swallowed failure;
- sources the build does not compile are recorded as unresolved, so
findings naming them drop a confidence step.
One rule-side change, optional and Dart-neutral: an EmissionSite may name
its stateType. rendered-not-emitted attributed indirect emissions by owner
(a bloc owns one state type), so a cast to one enum made "never emitted"
unprovable for every other enum in the same C++ class. With stateType
set, the suppression is scoped to that enum. Dart output is still byte
identical on the fixture and all four dogfood apps.
Run on ~/work/tools/yams (375 translation units from build/debug, 0 clang
errors, about two minutes): 118 state enums, 82 findings. A grep-based
hand check of 13 found 12 factually correct - e.g. the IPC connection FSM
never enters ImplState::ReadingHeader, the downloader never reports
ProgressStage::Verifying though three CLI commands render it,
ExtractScopeType qualifiers are parsed but never acted on - and one false
positive (a nested JSON-parse fallback taken for a stuck busy state),
now excluded by requiring the method's own state and a top-level try.
Bugs found on the way and fixed: ccache/compiler wrappers passed as
inputs, relative -I paths resolved against the wrong directory (7 TUs
silently lost third_party headers), a symlinked path putting every TU
"outside" the project, and an empty compile database producing an empty
"clean" model with exit 0 - all now fail loudly or are handled.
test/cpp_front_test.dart runs the front end on test/fixtures/cpp_state
with positive and negative controls for each rule; skipped without LLVM.
138 tests pass.
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