Fix failure on reset attrs with multiple list entries (#66)

Fixes #64

examples/cc_asan_test_with_reset/BUILD.bazel

@@ -5,14 +5,29 @@ load("@with_cfg.bzl", "original_settings")
 cc_asan_test(
     name = "asan_test",
     srcs = ["asan_test.cpp"],
+    # These synthetic references to targets demonstrate that attributes that are
+    # reset still support complex values such as selects.
     data = [
-        ":untransitioned_target",
-    ],
+        ":untransitioned_target_1",
+        ":untransitioned_target_2",
+    ] + select({
+        "@platforms//os:windows": [
+            ":untransitioned_target_3",
+            ":untransitioned_target_4",
+        ],
+        "//conditions:default": [
+            ":untransitioned_target_5",
+            ":untransitioned_target_6",
+        ],
+    }),
     env = {
         # Effectively invert the exit code so that the test passes if and only
         # if the expected ASAN error is detected.
         "ASAN_OPTIONS": "exitcode=0:abort_on_error=0",
     },
+    # Verify that an attr.label (rather than an attr.label_list) is handled correctly, this is
+    # otherwise a no-op.
+    win_def_file = ":asan_test.def",
     deps = [
         ":lib",
     ],
@@ -32,10 +47,15 @@ cc_asan_test_reset(
     exports = "//cc_asan_test_with_reset/third_party:large_dep",
 )
 
-untransitioned_target(
-    name = "untransitioned_target",
-)
-
 original_settings(
     name = "cc_asan_test_original_settings",
 )
+
+# These synthetic targets verify that they are not affected by any
+# transition.
+[
+    untransitioned_target(
+        name = "untransitioned_target_" + str(i),
+    )
+    for i in range(1, 7)
+]

examples/cc_asan_test_with_reset/cc_asan_test.bzl

@@ -8,5 +8,5 @@ _builder.extend("linkopt", select({
     "//conditions:default": ["-fsanitize=address"],
 }))
 _builder.resettable(Label(":cc_asan_test_original_settings"))
-_builder.reset_on_attrs("data", "srcs")
+_builder.reset_on_attrs("data", "srcs", "win_def_file")
 cc_asan_test, cc_asan_test_reset = _builder.build()

with_cfg/private/wrapper.bzl

@@ -222,7 +222,7 @@ def _process_attrs_for_reset(*, attrs, attrs_to_reset, reset_target, basename):
 def _replace_dep_attr(*, dep, label_map, reset_target, base_target_name, mutable_num_calls):
     if is_list(dep):
         # attr.label_list
-        result = [
+        return [
             _replace_single_dep(
                 label_string = label_string,
                 label_map = label_map,
@@ -234,7 +234,7 @@ def _replace_dep_attr(*, dep, label_map, reset_target, base_target_name, mutable
         ]
     elif is_dict(dep):
         # attr.label_keyed_string_dict (only the keys represent deps)
-        result = {
+        return {
             _replace_single_dep(
                 label_string = label_string,
                 label_map = label_map,
@@ -246,17 +246,14 @@ def _replace_dep_attr(*, dep, label_map, reset_target, base_target_name, mutable
         }
     else:
         # attr.label
-        result = _replace_single_dep(
+        return _replace_single_dep(
             label_string = dep,
             label_map = label_map,
             reset_target = reset_target,
             base_target_name = base_target_name,
             mutable_num_calls = mutable_num_calls,
         )
 
-    mutable_num_calls[0] += 1
-    return result
-
 def _replace_single_dep(
         *,
         label_string,
@@ -279,4 +276,6 @@ def _replace_single_dep(
         )
         target_label_string = ":" + target_name
         label_map[label] = target_label_string
+        mutable_num_calls[0] += 1
+
     return native.package_relative_label(target_label_string) if use_label else target_label_string