Both ecosystems are supported. They are not interchangeable:

gcov/lcov read GCC counters (.gcno / .gcda)
llvm-cov/llvm-profdata read Clang's (.profraw / .profdata)

Tool	Toolchain	build	static-analysis	documentation	dev
gcov, gcov-tool	GNU	✅	✅	✅	✅
lcov, genhtml	GNU			✅	✅
llvm-cov, llvm-profdata	LLVM		✅	✅	✅

# GNU: gcov counters -> lcov/genhtml HTML report
g++ --coverage main.cpp -o app && ./app
lcov --capture --directory . --output-file cov.info && genhtml cov.info --output-directory html
 
# LLVM: instrumented profile -> llvm-profdata -> llvm-cov
clang++ -fprofile-instr-generate -fcoverage-mapping main.cpp -o app
LLVM_PROFILE_FILE=app.profraw ./app
llvm-profdata merge -sparse app.profraw -o app.profdata
llvm-cov show ./app -instr-profile=app.profdata

build installs Clang minimalistically, which stops short of the llvm-<N> package that carries llvm-cov and llvm-profdata, so neither is present there in any form. static-analysis pulls them in transitively through the full LLVM toolchain, documentation installs llvm-<N> outright, and both register the unversioned commands. lcov (the Perl frontend producing HTML) ships in the coverage-oriented stages only - gcov itself always comes with GCC.

Tip: llvm-cov compatibility mode

llvm-cov can also read GCC-style counters via its llvm-cov gcov compatibility mode, so lcov --gcov-tool "llvm-cov gcov" bridges Clang-compiled coverage into an lcov report.

See also