Use ctx.coverage_instrumented to detect if a target should be instrumented (#1547)

Signed-off-by: Brentley Jones <[email protected]>
Co-authored-by: Fabian Meumertzheim <[email protected]>

Author: brentleyjones

swift/internal/features.bzl

@@ -96,17 +96,21 @@ def configure_features(
         passed to other `swift_common` functions. Note that the structure of
         this value should otherwise not be relied on or inspected directly.
     """
+    requested_features = list(requested_features)
+    unsupported_features = list(unsupported_features)
 
     # Always disable these two features so that any `cc_common` APIs called by
     # `swift_common` APIs don't cause certain actions to be created (for
     # example, when using `cc_common.compile` to create the compilation context
     # for a generated header).
-    unsupported_features = list(unsupported_features)
     unsupported_features.extend([
         "cc_include_scanning",
         "parse_headers",
     ])
 
+    if ctx.coverage_instrumented():
+        requested_features.append(SWIFT_FEATURE_COVERAGE)
+
     # HACK: This is the only way today to check whether the caller is inside an
     # aspect. We have to do this because accessing `ctx.aspect_ids` halts the
     # build if called from outside an aspect, but we can't use `hasattr` to
@@ -180,8 +184,6 @@ def features_for_build_modes(ctx, cpp_fragment = None):
     compilation_mode = ctx.var["COMPILATION_MODE"]
     features = []
     features.append("swift.{}".format(compilation_mode))
-    if ctx.configuration.coverage_enabled:
-        features.append(SWIFT_FEATURE_COVERAGE)
     if compilation_mode in ("dbg", "fastbuild"):
         features.append(SWIFT_FEATURE_ENABLE_TESTING)
     if cpp_fragment and cpp_fragment.apple_generate_dsym: