Expand dependency tracking patterns using Label

Replaced `apparent_repo_label_string` and `adjust_main_repo_prefix`
based on an idea from @fmeum during his review of
bazelbuild/bazel-skylib#548.

Added `_expand_patterns`, which uses `native.package_relative_label` to
expand the `dependency_tracking_*_deps_patterns` attributes to full,
correct `Label` strings.

All `test/shell/test_{strict,unused}_dependency.sh` test cases pass.

Author: mbland

scala/private/macros/bzlmod.bzl

@@ -1,22 +1,8 @@
 """Utilities for working with Bazel modules"""
 
-def _repo_name(label_or_name):
-    """Utility to provide Label compatibility with Bazel 5.
-
-    Under Bazel 5, calls `Label.workspace_name`. Otherwise calls
-    `Label.repo_name`.
-
-    Args:
-        label_or_name: a Label or repository name string
-
-    Returns:
-        The repository name returned directly from the Label API, or the
-            original string if not a Label
-    """
-    if hasattr(label_or_name, "repo_name"):
-        return label_or_name.repo_name
-
-    return getattr(label_or_name, "workspace_name", label_or_name)
+_repo_attr = (
+    "repo_name" if hasattr(Label("//:all"), "repo_name") else "workspace_name"
+)
 
 def apparent_repo_name(label_or_name):
     """Return a repository's apparent repository name.
@@ -30,7 +16,7 @@ def apparent_repo_name(label_or_name):
     Returns:
         The apparent repository name
     """
-    repo_name = _repo_name(label_or_name).lstrip("@")
+    repo_name = getattr(label_or_name, _repo_attr, label_or_name).lstrip("@")
     delimiter_indices = []
 
     # Bazed on this pattern from the Bazel source:
@@ -49,44 +35,3 @@ def apparent_repo_name(label_or_name):
         return repo_name[:delimiter_indices[0]]
 
     return repo_name[delimiter_indices[-1] + 1:]
-
-def apparent_repo_label_string(label):
-    """Return a Label string starting with its apparent repo name.
-
-    Args:
-        label: a Label instance
-
-    Returns:
-        str(label) with its canonical repository name replaced with its apparent
-            repository name
-    """
-    repo_name = _repo_name(label)
-    if len(repo_name) == 0:
-        return str(label)
-
-    label_str = "@" + str(label).lstrip("@")
-    return label_str.replace(label.repo_name, apparent_repo_name(label))
-
-_IS_BZLMOD_ENABLED = str(Label("//:all")).startswith("@@")
-
-_MAIN_REPO_PREFIX = "@@//" if _IS_BZLMOD_ENABLED else "@//"
-
-def adjust_main_repo_prefix(target_pattern):
-    """Updates the main repo prefix to match the current Bazel version.
-
-    The main repo prefix will be "@//" for Bazel < 7.1.0, and "@@//" for Bazel
-    >= 7.1.0 under Bzlmod. This macro automatically updates strings representing
-    include/exclude target patterns so that they match actual main repository
-    target Labels correctly.
-
-    Args:
-        target_pattern: a string used to match a BUILD target pattern
-
-    Returns:
-        the string with any main repository prefix updated to match the current
-            Bazel version
-    """
-    if target_pattern.startswith("@//") or target_pattern.startswith("@@//"):
-        return _MAIN_REPO_PREFIX + target_pattern.lstrip("@/")
-
-    return target_pattern

scala/private/phases/phase_dependency.bzl

@@ -6,7 +6,6 @@ load(
     "get_strict_deps_mode",
     "new_dependency_info",
 )
-load("//scala/private:macros/bzlmod.bzl", "apparent_repo_label_string")
 load(
     "//scala/private:paths.bzl",
     _get_files_with_extension = "get_files_with_extension",
@@ -38,7 +37,7 @@ def _phase_dependency(
         strict_deps_always_off):
     toolchain = ctx.toolchains[Label("//scala:toolchain_type")]
 
-    target_label = apparent_repo_label_string(ctx.label)
+    target_label = str(ctx.label)
 
     included_in_strict_deps_analysis = _is_target_included(
         target_label,

scala/scala_toolchain.bzl

@@ -1,4 +1,3 @@
-load("//scala/private:macros/bzlmod.bzl", "adjust_main_repo_prefix")
 load("//scala:providers.bzl", _DepsInfo = "DepsInfo")
 load(
     "@io_bazel_rules_scala_config//:config.bzl",
@@ -29,12 +28,12 @@ def _compute_dependency_tracking_method(
 
 def _partition_patterns(patterns):
     includes = [
-        adjust_main_repo_prefix(pattern)
+        pattern
         for pattern in patterns
         if not pattern.startswith("-")
     ]
     excludes = [
-        adjust_main_repo_prefix(pattern.lstrip("-"))
+        pattern.lstrip("-")
         for pattern in patterns
         if pattern.startswith("-")
     ]
@@ -116,7 +115,7 @@ def _default_dep_providers():
         dep_providers.append("semanticdb")
     return [Label("//scala:%s_provider" % p) for p in dep_providers]
 
-scala_toolchain = rule(
+_scala_toolchain = rule(
     _scala_toolchain_impl,
     attrs = {
         "scalacopts": attr.string_list(),
@@ -177,3 +176,31 @@ scala_toolchain = rule(
     },
     fragments = ["java"],
 )
+
+def _expand_patterns(patterns):
+    """Expands string patterns to match actual Label values."""
+    result = []
+
+    for p in patterns:
+        exclude = p.startswith("-")
+        p = p.lstrip("-")
+        expanded = str(native.package_relative_label(p)) if p else ""
+
+        # If the original pattern doesn't contain ":", match any target
+        # beginning with the pattern prefix.
+        if expanded and ":" not in p:
+            expanded = expanded[:expanded.rindex(":")]
+
+        result.append(("-" if exclude else "") + expanded)
+
+    return result
+
+def scala_toolchain(**kwargs):
+    """Creates a Scala toolchain target."""
+    strict = kwargs.pop("dependency_tracking_strict_deps_patterns", [""])
+    unused = kwargs.pop("dependency_tracking_unused_deps_patterns", [""])
+    _scala_toolchain(
+        dependency_tracking_strict_deps_patterns = _expand_patterns(strict),
+        dependency_tracking_unused_deps_patterns = _expand_patterns(unused),
+        **kwargs,
+    )