[pitboss] phase 03: Track A.3 — LangEmitter::entry_kinds_supported + actionable Inconclusive hints

src/dynamic/lang/cpp.rs

@@ -0,0 +1,52 @@
+//! C++ harness emitter (stub).
+//!
+//! No harness source is generated yet — `emit` returns
+//! [`UnsupportedReason::LangUnsupported`].  The module exists so that
+//! [`crate::dynamic::lang::entry_kinds_supported`] can advertise the entry
+//! kinds Track B will deliver (Phase 16: `main(argc, argv)`,
+//! `LLVMFuzzerTestOneInput`, free functions with `(const char*, size_t)`)
+//! and so the verifier can surface `Inconclusive(EntryKindUnsupported { … })`
+//! instead of dropping C++ findings.
+
+use crate::dynamic::lang::{HarnessSource, LangEmitter};
+use crate::dynamic::spec::{EntryKind, HarnessSpec};
+use crate::evidence::UnsupportedReason;
+
+/// Zero-sized [`LangEmitter`] handle for C++.
+pub struct CppEmitter;
+
+/// Entry kinds the C++ emitter intends to support once Phase 16 lands.
+const SUPPORTED: &[EntryKind] = &[EntryKind::Function];
+
+impl LangEmitter for CppEmitter {
+    fn emit(&self, _spec: &HarnessSpec) -> Result<HarnessSource, UnsupportedReason> {
+        Err(UnsupportedReason::LangUnsupported)
+    }
+
+    fn entry_kinds_supported(&self) -> &'static [EntryKind] {
+        SUPPORTED
+    }
+
+    fn entry_kind_hint(&self, attempted: EntryKind) -> String {
+        format!(
+            "cpp emitter is a stub; once Phase 16 (Track B Rust + C/C++ vertical) lands it will support {SUPPORTED:?} plus libFuzzer + main(argc, argv) shapes — attempted `EntryKind::{attempted}`"
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn entry_kinds_supported_is_non_empty() {
+        assert!(!CppEmitter.entry_kinds_supported().is_empty());
+    }
+
+    #[test]
+    fn entry_kind_hint_names_attempted_and_phase() {
+        let hint = CppEmitter.entry_kind_hint(EntryKind::CliSubcommand);
+        assert!(hint.contains("CliSubcommand"));
+        assert!(hint.contains("Phase 16"));
+    }
+}