Switch coverage to clang, ensure out dir for config exists

build/config/compiler/BUILD.gn

@@ -536,7 +536,16 @@ config("fuzzing_default") {
 }
 
 config("coverage") {
-  cflags = [ "--coverage" ]
+  if (is_clang) {
+    cflags = [
+      # CLANG builds use the clang-specific coverage, so that versions of lcov/gcov
+      # do not have to match and `llvm-cov export -format=lcov` can be used
+      "-fprofile-instr-generate",
+      "-fcoverage-mapping",
+    ]
+  } else {
+    cflags = [ "--coverage" ]
+  }
   ldflags = cflags
 }
 

scripts/tests/local.py

@@ -82,6 +82,8 @@ def _get_variants(coverage: Optional[bool]):
     else:
         config["OPTIONS"]["coverage"] = "false"
 
+    if not os.path.exists("./out"):
+        os.mkdir("./out")
     with open(config_path, "w") as f:
         config.write(f)
 
@@ -517,7 +519,7 @@ def as_runner(path):
         return _maybe_with_runner(os.path.basename(path), path, runner)
 
     # create an env file
-    with open("out/test_env.yaml", "wt") as f:
+    with open("./out/test_env.yaml", "wt") as f:
         for target in _get_targets(coverage):
             run_path = as_runner(f"out/{target.target}/{target.binary}")
             f.write(f"{target.key}: {run_path}\n")