Create baseline coverage report if supported

java/common/rules/impl/basic_java_library_impl.bzl

@@ -16,6 +16,7 @@
 Common code for reuse across java_* rules
 """
 
+load("@bazel_features//:features.bzl", "bazel_features")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("//java/common/rules:android_lint.bzl", "android_lint_subrule")
 load("//java/private:boot_class_path_info.bzl", "BootClassPathInfo")
@@ -124,6 +125,14 @@ def basic_java_library(
         resources = list(resources)
         resources.extend(properties)
 
+    baseline_coverage_file = None
+    if (
+        bazel_features.rules.instrumented_files_info_has_baseline_coverage_files and
+        ctx.coverage_instrumented() and
+        source_files
+    ):
+        baseline_coverage_file = ctx.actions.declare_file(ctx.label.name + "_baseline_coverage.dat")
+
     java_info, compilation_info = compile_action(
         ctx,
         output_class_jar = ctx.outputs.classjar,
@@ -147,6 +156,7 @@ def basic_java_library(
         add_opens = add_opens,
         bootclasspath = bootclasspath[BootClassPathInfo] if bootclasspath else None,
         javabuilder_jvm_flags = javabuilder_jvm_flags,
+        baseline_coverage_file = baseline_coverage_file,
     )
     target = {"JavaInfo": java_info}
 
@@ -178,12 +188,16 @@ def basic_java_library(
     if validation_outputs:
         output_groups["_validation"] = depset(transitive = validation_outputs)
 
+    instrumented_files_info_kwargs = {}
+    if baseline_coverage_file:
+        instrumented_files_info_kwargs["baseline_coverage_files"] = [baseline_coverage_file]
     target["InstrumentedFilesInfo"] = coverage_common.instrumented_files_info(
         ctx,
         source_attributes = ["srcs"],
         dependency_attributes = ["deps", "data", "resources", "resource_jars", "exports", "runtime_deps", "jars"],
         coverage_support_files = coverage_config.support_files if coverage_config else depset(),
         coverage_environment = coverage_config.env if coverage_config else {},
+        **instrumented_files_info_kwargs
     )
 
     if proguard_specs != None:

java/common/rules/impl/compile_action.bzl

@@ -60,7 +60,8 @@ def compile_action(
         add_exports = [],
         add_opens = [],
         bootclasspath = None,
-        javabuilder_jvm_flags = None):
+        javabuilder_jvm_flags = None,
+        baseline_coverage_file = None):
     """
     Creates actions that compile Java sources, produce source jar, and produce header jar and returns JavaInfo.
 
@@ -123,6 +124,7 @@ def compile_action(
       add_opens: (list[str]) Allow this library to reflectively access the given <module>/<package>.
       bootclasspath: (BootClassPathInfo) The set of JDK APIs to compile this library against.
       javabuilder_jvm_flags: (list[str]) Additional JVM flags to pass to JavaBuilder.
+      baseline_coverage_file: (File) Baseline coverage report to generate during compilation.
 
     Returns:
       ((JavaInfo, {files_to_build: list[File],
@@ -160,6 +162,7 @@ def compile_action(
         add_opens = add_opens,
         bootclasspath = bootclasspath,
         javabuilder_jvm_flags = javabuilder_jvm_flags,
+        baseline_coverage_file = baseline_coverage_file,
     )
 
     compilation_info = struct(

java/private/java_common_internal.bzl

@@ -68,7 +68,8 @@ def compile(
         include_compilation_info = True,
         classpath_resources = [],
         resource_jars = [],
-        injecting_rule_kind = None):
+        injecting_rule_kind = None,
+        baseline_coverage_file = None):
     """Compiles Java source files/jars from the implementation of a Starlark rule
 
     The result is a provider that represents the results of the compilation and can be added to the
@@ -115,6 +116,7 @@ def compile(
         enable_jspecify: (bool)
         include_compilation_info: (bool)
         injecting_rule_kind: (str|None)
+        baseline_coverage_file: (File)
         add_exports: ([str]) Allow this library to access the given <module>/<package>. Optional.
         add_opens: ([str]) Allow this library to reflectively access the given <module>/<package>.
              Optional.
@@ -309,6 +311,7 @@ def compile(
         enable_direct_classpath,
         annotation_processor_additional_inputs,
         annotation_processor_additional_outputs,
+        baseline_coverage_file,
     )
 
     create_output_source_jar = len(source_files) > 0 or source_jars != [output_source_jar]