Stop listing .gcno files as outputs when using LLVM coverage map fo…

…rmat

When using `--experimental_use_llvm_covmap`, no `.gcno` files are output. By listing them as outputs there is a mismatch between expected and actual outputs. Bazel will create these empty files after the action is run, but they non-deterministically get counted in the Action outputs, which can lead to cache misses on subsequent runs.

Signed-off-by: Brentley Jones <github@brentleyjones.com>

src/main/java/com/google/devtools/build/lib/rules/cpp/CcCompilationHelper.java

@@ -1410,7 +1410,7 @@ private void createModuleCodegenAction(
             ccToolchain, ArtifactCategory.COVERAGE_DATA_FILE, outputName);
     // TODO(djasper): This is now duplicated. Refactor the various create..Action functions.
     Artifact gcnoFile =
-        isCodeCoverageEnabled
+        isCodeCoverageEnabled && !cppConfiguration.useLLVMCoverageMapFormat()
             ? CppHelper.getCompileOutputArtifact(
                 actionConstructionContext, label, gcnoFileName, configuration)
             : null;
@@ -1541,7 +1541,7 @@ private ImmutableList<Artifact> createSourceAction(
           CppHelper.getArtifactNameForCategory(
               ccToolchain, ArtifactCategory.COVERAGE_DATA_FILE, picOutputBase);
       Artifact gcnoFile =
-          enableCoverage
+          isCodeCoverageEnabled && !cppConfiguration.useLLVMCoverageMapFormat()
               ? CppHelper.getCompileOutputArtifact(
                   actionConstructionContext, label, gcnoFileName, configuration)
               : null;
@@ -1615,7 +1615,7 @@ private ImmutableList<Artifact> createSourceAction(
 
       // Create no-PIC compile actions
       Artifact gcnoFile =
-          enableCoverage
+          isCodeCoverageEnabled && !cppConfiguration.useLLVMCoverageMapFormat()
               ? CppHelper.getCompileOutputArtifact(
                   actionConstructionContext, label, gcnoFileName, configuration)
               : null;