[javac/kt] Supply the correct system path for j2kt when compiling wit…

…h javac.

PiperOrigin-RevId: 696683151

build_defs/internal_do_not_use/j2cl_common.bzl

@@ -27,12 +27,6 @@ def _compile(
     java_toolchain = _get_java_toolchain(ctx)
     jvm_srcs, js_srcs = split_srcs(srcs)
 
-    # Heuristic to determine if we need to specify the jre module. Our jre defines --system=none.
-    jdk_system_set = any([s for s in javac_opts if s.startswith("--system")])
-
-    # TODO(b/197211878): Switch to a public API when available.
-    [jdk_system] = java_toolchain._bootclasspath_info._system_inputs.to_list() if not jdk_system_set else [None]
-
     has_srcs_to_transpile = (jvm_srcs or kt_common_srcs)
     has_kotlin_srcs = any([src for src in jvm_srcs if src.extension == "kt"]) or kt_common_srcs
 
@@ -87,7 +81,7 @@ def _compile(
         _j2cl_transpile(
             ctx,
             jvm_provider,
-            jdk_system,
+            get_jdk_system(java_toolchain, javac_opts),
             js_srcs,
             output_js,
             output_library_info,
@@ -233,6 +227,18 @@ def _kt_compile(
 def _get_java_toolchain(ctx):
     return ctx.attr._j2cl_java_toolchain[java_common.JavaToolchainInfo]
 
+def get_jdk_system(java_toolchain, javac_opts):
+    """ Returns the path to the system module directory.
+
+    The path is returned in a single-element list or empty list if compiling the JRE itself.
+    """
+
+    # Heuristic to determine if we need to specify the jre module. Our jre defines --system=none.
+    jdk_system_already_set = any([s.startswith("--system") for s in javac_opts])
+
+    # TODO(b/197211878): Switch to a public API when available.
+    return java_toolchain._bootclasspath_info._system_inputs.to_list() if not jdk_system_already_set else []
+
 def _strip_incompatible_annotation(ctx, name, java_srcs, mnemonic, strip_annotation):
     # Paths are matched by Kythe to identify generated J2CL sources.
     output_file = ctx.actions.declare_file(name + "_j2cl_stripped-src.jar")
@@ -298,9 +304,7 @@ def _j2cl_transpile(
     args.use_param_file("@%s", use_always = True)
     args.set_param_file_format("multiline")
     args.add_joined("-classpath", classpath, join_with = ctx.configuration.host_path_separator)
-
-    if jdk_system:
-        args.add("-system", jdk_system.path)
+    args.add_all("-system", jdk_system, expand_directories = False)
 
     # Explicitly format this as Bazel target labels can start with a @, which
     # can be misinterpreted as a flag file to load.
@@ -338,7 +342,7 @@ def _j2cl_transpile(
         # kt_common_srcs are not read by the transpiler as they are already
         # included in the srcjars of srcs. However, params.add_all requires them
         # to be inputs in order to be properly expanded out into params.
-        inputs = depset(srcs + kt_common_srcs + ([jdk_system] if jdk_system else []), transitive = [classpath]),
+        inputs = depset(srcs + kt_common_srcs + jdk_system, transitive = [classpath]),
         outputs = [output_dir, library_info_output],
         executable = j2cl_transpiler_override or ctx.executable._j2cl_transpiler,
         arguments = [args],