github/workflows: Switch from lcov to gcov.

Coverage calculated by Codecov has the same reliability/deterministic
issues as Coveralls did, so the problem is likely to do with the output of
lcov/gcov, rather than the analysis and display of the data.

Switch from lcov to gcov for data generation to try and simplify this
process of computing coverage.

Signed-off-by: Damien George <damien@micropython.org>

.github/workflows/ports_unix.yml

@@ -65,15 +65,13 @@ jobs:
       run: source tools/ci.sh && ci_native_mpy_modules_build
     - name: Test importing .mpy generated by mpy_ld.py
       run: source tools/ci.sh && ci_unix_coverage_run_native_mpy_tests
-    - name: Run lcov coverage analysis
+    - name: Run gcov coverage analysis
       run: |
-        mkdir -p coverage
+        (cd ports/unix && gcov -o build-coverage/py ../../py/*.c || true)
-        lcov --rc lcov_branch_coverage=1 --directory ports/unix/build-coverage --capture --output-file coverage/lcov.info.all
+        (cd ports/unix && gcov -o build-coverage/extmod ../../extmod/*.c || true)
-        lcov --remove coverage/lcov.info.all '*/lib/*' '*/ports/unix/*' '*/utils/*' --output-file coverage/lcov.info
     - name: Upload coverage to Codecov
       uses: codecov/codecov-action@v1
       with:
-        files: coverage/lcov.info
         fail_ci_if_error: true
         verbose: true
     - name: Print failures

tools/ci.sh

@@ -394,7 +394,6 @@ function ci_unix_standard_run_perfbench {
 }
 
 function ci_unix_coverage_setup {
-    sudo apt-get install lcov
     sudo pip3 install setuptools
     sudo pip3 install pyelftools
     gcc --version