Skip coverage build in CI for non C/C++ projects. (#4075)

* Skip coverage build in CI for non C/C++ projects.

Fixes https://github.com/google/oss-fuzz/issues/4074

* Test wasmtime.

infra/ci/build.py

@@ -28,6 +28,9 @@ DEFAULT_ARCHITECTURES = ['x86_64']
 DEFAULT_ENGINES = ['afl', 'honggfuzz', 'libfuzzer']
 DEFAULT_SANITIZERS = ['address', 'undefined']
 
+# Languages from project.yaml that have code coverage support.
+LANGUAGES_WITH_COVERAGE_SUPPORT = ['c', 'c++']
+
 
 def get_modified_buildable_projects():
   """Returns a list of all the projects modified in this commit that have a
@@ -112,6 +115,14 @@ def build_project(project):
   engine = os.getenv('ENGINE')
   sanitizer = os.getenv('SANITIZER')
   architecture = os.getenv('ARCHITECTURE')
+  language = project_yaml.get('language')
+
+  if (sanitizer == 'coverage' and
+      language not in LANGUAGES_WITH_COVERAGE_SUPPORT):
+    print(('Project "{project}" is written in "{language}", '
+           'coverage is not supported yet.').format(project=project,
+                                                    language=language))
+    return
 
   if sanitizer != 'coverage' and not should_build(project_yaml):
     print(('Specified build: engine: {0}, sanitizer: {1}, architecture: {2} '

projects/wasmtime/build.sh

@@ -23,6 +23,7 @@ PROJECT_DIR=$SRC/wasmtime
 cd $PROJECT_DIR/fuzz && cargo fuzz build -O --debug-assertions --all-features
 
 FUZZ_TARGET_OUTPUT_DIR=$PROJECT_DIR/target/x86_64-unknown-linux-gnu/release
+
 for f in $SRC/wasmtime/fuzz/fuzz_targets/*.rs
 do
     FUZZ_TARGET_NAME=$(basename ${f%.*})