Add a workaround for gcov-based coverage with clang

- Allow overriding the gcov tool with the GCOV env variable in cc_configure
- Symlink the GCOV tool in collect-coverage.sh to a temporary location with
  the name "gcov"

This allows the user to specify GCOV=llvm-cov in the environment of a bazel
build, which then leads to cc_configure picking up llvm-cov in the crosstool,
which the collect-coverage.sh script then uses as "gcov".

On linux distributions, the gcov tool does not generally work with clang
coverage output, so this provides at least a workaround for running coverage
with clang (by setting the GCOV env variable).

Closes #5040.

PiperOrigin-RevId: 193487773

1 files changed, 8 insertions, 0 deletions

diff --git a/tools/test/collect_coverage.sh b/tools/test/collect_coverage.sh
index aba56c0ee1..b9579cac99 100755
--- a/tools/test/collect_coverage.sh
+++ b/tools/test/collect_coverage.sh
@@ -126,13 +126,21 @@ if [[ "$COVERAGE_LEGACY_MODE" ]]; then
     touch "${COVERAGE_DIR}/${path}"
   done
 
+  # Symlink the gcov tool such with a link called gcov. Clang comes with a tool
+  # called llvm-cov, which behaves like gcov if symlinked in this way (otherwise
+  # we would need to invoke it with "llvm-cov gcov").
+  GCOV="${COVERAGE_DIR}/gcov"
+  ln -s "${COVERAGE_GCOV_PATH}" "${GCOV}"
+
   # Run lcov over the .gcno and .gcda files to generate the lcov tracefile.
   # -c - Collect coverage data
   # --no-external - Do not collect coverage data for system files
   # --ignore-errors graph - Ignore missing .gcno files; Bazel only instruments some files
+  # --gcov-tool "${GCOV}" - Pass the local symlink to be uses as gcov by lcov
   # -d "${COVERAGE_DIR}" - Directory to search for .gcda files
   # -o "${COVERAGE_OUTPUT_FILE}" - Output file
   /usr/bin/lcov -c --no-external --ignore-errors graph \
+      --gcov-tool "${GCOV}" \
       -d "${COVERAGE_DIR}" -o "${COVERAGE_OUTPUT_FILE}"
 
   # The paths are all wrong, because they point to /tmp. Fix up the paths to