fix: modern rule check

- fix: explicitly check against modern rule status before resolving
  toolchain, unconditionally take it if running modern
- fix: direct deps for `native_image_tool` attr
- fix: preserve legacy rule behavior

applies on top of #70

Signed-off-by: Sam Gammon <sam@elide.ventures>

internal/native_image/rules.bzl

@@ -107,28 +107,39 @@ def _graal_binary_implementation(ctx):
  direct_inputs = []
  transitive_inputs = [classpath_depset]
 
- if graal_attr == None:
+ # if we aren't handed a specific `native-image` tool binary, or we are running
+ # under the modern `native_image` rule, then attempt to resolve via toolchains...
+ if graal_attr == None and not (ctx.attr._legacy_rule):
  # resolve via toolchains
  info = ctx.toolchains[_GVM_TOOLCHAIN_TYPE].graalvm
- graal_attr = info.native_image_bin
+
+ # but fall back to explicitly-provided tool, which should override, with the
+ # remainder of the resolved toolchain present
+ resolved_graal = graal_attr or info.native_image_bin
  gvm_toolchain = info
  extra_tool_deps.append(info.gvm_files)
 
  graal_inputs, _ = ctx.resolve_tools(tools = [
- graal_attr,
+ resolved_graal,
  ] + extra_tool_deps)
 
  graal = graal_inputs.to_list()[0]
+
+ # if we're using an explicit tool, add it to the direct inputs
+ if graal_attr:
+ direct_inputs.append(graal_inputs)
+
+ # add toolchain files to transitive inputs
  transitive_inputs.append(gvm_toolchain.gvm_files[DefaultInfo].files)
- else:
- # otherwise, use the legacy code path
+ elif graal_attr != None:
+ # otherwise, use the legacy code path. the `graal` value is used in the run
+ # `executable` so it isn't listed in deps for earlier Bazel versions.
  graal_inputs, _, _ = ctx.resolve_command(tools = [
  graal_attr,
  ])
  graal = graal_inputs[0]
- direct_inputs.append(graal_inputs)
-
- if graal_attr == None:
+ direct_inputs.append(graal)
+ else:
  # still failed to resolve: cannot resolve via either toolchains or attributes.
  fail("""
  No `native-image` tool found. Please either define a `native_image_tool` in your target,
@@ -263,6 +274,7 @@ def _graal_binary_implementation(ctx):
  args.add("-H:+JNI")
 
  inputs = depset(direct_inputs, transitive = transitive_inputs)
+
  run_params = {
  "outputs": [binary],
  "arguments": [args],