BullseyeCoverage vs cargo-llvm-cov

BullseyeCoverage measures C and C++ code coverage to help developers and testers locate untested code and assess testing completeness. It provides function coverage and condition/decision coverage, and results can be viewed interactively in Coverage Browser or generated as reports. Listed outputs include HTML, text, annotated source code, XML, Cobertura, and CSV. The tool instruments C and C++ source code and supports standard C++ versions from C++98 and C versions from C90 through current versions, plus compiler extensions. Coverage data can be exported in XML or CSV, and results from multiple computers can be merged. Supported tools include Visual Studio, Clang, GCC, Xcode, CMake, Eclipse, and embedded development tools such as Code Composer Studio. Supported environments include Windows, Linux desktop and server, macOS, and embedded systems. The company reports that instrumented execution takes 1.3–1.9× longer and code and data size increase to 1.4×; build-time effects vary by compiler. A temporary, fully functional evaluation license costs nothing and expires at the end of its evaluation period. The perpetual paid license has no listed price.

cargo-llvm-cov is a Cargo subcommand that uses rustc’s LLVM source-based instrumentation to generate code coverage reports. It works with cargo test, cargo run, and cargo nextest through a Cargo-compatible command-line interface, and supports proc-macro UI tests. Line and region coverage are available; branch coverage is optional and requires nightly Rust. Doc-test coverage is also optional and requires nightly features. Reports can be generated as text, HTML, JSON, LCOV, Cobertura XML, or Codecov Custom Coverage format. The project provides GitHub Actions examples for uploading reports to Codecov and a GitLab CI example using Cobertura output. LCOV results can be viewed in VS Code with the Coverage Gutters extension. With compatible Clang and LLVM tools configured, the tool can include C and C++ code linked to a Rust library or binary. It supports Linux, macOS, and Windows, and is licensed under either Apache-2.0 or MIT at the user's choice. Installation requires rustc 1.87 or newer, while running it requires Cargo 1.60 or newer. Branch and doc-test coverage are unstable and have known issues, respectively.