Enable code coverage in Xcode

Signed-off-by: Aaron Sky <aaronsky@skyaaron.com>

Author: aaronsky

xcodeproj/internal/templates/generate_bazel_dependencies.sh

@@ -121,6 +121,8 @@ if [ "$ACTION" == "indexbuild" ]; then
   apply_sanitizers=0
 elif [ "${ENABLE_PREVIEWS:-}" == "YES" ]; then
   readonly config="${BAZEL_CONFIG}_swiftuipreviews"
+elif [ "${ENABLE_CODE_COVERAGE:-}" == "YES" ]; then
+  readonly config="${BAZEL_CONFIG}_coverage"
 else
   readonly config="_${BAZEL_CONFIG}_build"
 fi

xcodeproj/internal/templates/xcodeproj.bazelrc

@@ -83,6 +83,33 @@ common:rules_xcodeproj_indexbuild --config=rules_xcodeproj
 # Disable BES for Index Builds, as it runs a lot, and isn't user invoked
 common:rules_xcodeproj_indexbuild --bes_backend= --bes_results_url=
 
+### `--config=rules_xcodeproj_coverage`
+#
+# Used when doing building for code coverage.
+
+common:rules_xcodeproj_coverage --config=rules_xcodeproj
+
+# Enable features that allow for building for instrumentation.
+#
+# Of particular note are the (swift./)coverage_prefix_map_canonical_non_hermetic
+# features, which remap the execroot during the build as the absolute, canonical path
+# to the source root.
+#
+# This approach breaks remote caching when building for testing and codeCoverageEnabled
+# is set to YES, but does not affect other builds (for running, or for testing without
+# coverage).
+common:rules_xcodeproj_coverage --features=coverage
+common:rules_xcodeproj_coverage --features=llvm_coverage_map_format
+common:rules_xcodeproj_coverage --features=coverage_prefix_map_canonical_non_hermetic
+common:rules_xcodeproj_coverage --features=swift.coverage
+common:rules_xcodeproj_coverage --features=swift.coverage_prefix_map_canonical_non_hermetic
+
+# Disable features that interfere with (swift./)coverage_prefix_map_canonical_non_hermetic
+common:rules_xcodeproj_coverage --features=-coverage_prefix_map
+common:rules_xcodeproj_coverage --features=-file_prefix_map
+common:rules_xcodeproj_coverage --features=-swift.coverage_prefix_map
+common:rules_xcodeproj_coverage --features=-swift.file_prefix_map
+
 ### `--config=rules_xcodeproj_swiftuipreviews`
 #
 # Used when doing a Xcode Previews build.