Also report cycles involving WORKSPACE from BzlmodRepoCycleReporter

Work towards #20942

On the referenced bug, this prints:
```
ERROR: Circular definition of repositories generated by module extensions and/or .bzl files:
.-> repository mapping of @@
|   WORKSPACE file
|   //python:pip.bzl
|   //python/pip_install:requirements.bzl
|   //python:defs.bzl
|   //python:py_import.bzl
|   //python:py_info.bzl
|   @@_main~internal_deps~rules_python_internal//:rules_python_config.bzl
|   @@_main~internal_deps~rules_python_internal
|   extension 'internal_deps' defined in //python/private/bzlmod:internal_deps.bzl
`-- repository mapping of @@
ERROR: Error computing the main repository mapping: cycles detected during computation of main repo mapping
```

Closes #20958.

PiperOrigin-RevId: 601183514
Change-Id: If321005b1f6918117d0f5b5763ae2bda4d8e34f1

src/main/java/com/google/devtools/build/lib/skyframe/BUILD

@@ -2420,11 +2420,13 @@ java_library(
     deps = [
         ":abstract_label_cycle_reporter",
         ":bzl_load_value",
+        ":repository_mapping_value",
         ":sky_functions",
         "//src/main/java/com/google/devtools/build/lib/bazel/bzlmod:module_extension",
         "//src/main/java/com/google/devtools/build/lib/bazel/bzlmod:repo_rule_value",
         "//src/main/java/com/google/devtools/build/lib/cmdline",
         "//src/main/java/com/google/devtools/build/lib/events",
+        "//src/main/java/com/google/devtools/build/lib/packages",
         "//src/main/java/com/google/devtools/build/lib/repository:request_repository_information_event",
         "//src/main/java/com/google/devtools/build/lib/rules:repository/repository_directory_value",
         "//src/main/java/com/google/devtools/build/skyframe",

src/main/java/com/google/devtools/build/lib/skyframe/BzlmodRepoCycleReporter.java

@@ -26,6 +26,7 @@
 import com.google.devtools.build.lib.cmdline.PackageIdentifier;
 import com.google.devtools.build.lib.events.Event;
 import com.google.devtools.build.lib.events.ExtendedEventHandler;
+import com.google.devtools.build.lib.packages.WorkspaceFileValue;
 import com.google.devtools.build.lib.repository.RequestRepositoryInformationEvent;
 import com.google.devtools.build.lib.rules.repository.RepositoryDirectoryValue;
 import com.google.devtools.build.skyframe.CycleInfo;
@@ -53,6 +54,21 @@ public class BzlmodRepoCycleReporter implements CyclesReporter.SingleCycleReport
   private static final Predicate<SkyKey> IS_EXTENSION_IMPL =
       SkyFunctions.isSkyFunction(SkyFunctions.SINGLE_EXTENSION_EVAL);
 
+  private static final Predicate<SkyKey> IS_REPO_MAPPING =
+      SkyFunctions.isSkyFunction(SkyFunctions.REPOSITORY_MAPPING);
+
+  private static final Predicate<SkyKey> IS_MODULE_EXTENSION_REPO_MAPPING_ENTRIES =
+      SkyFunctions.isSkyFunction(SkyFunctions.MODULE_EXTENSION_REPO_MAPPING_ENTRIES);
+
+  private static final Predicate<SkyKey> IS_PACKAGE =
+      SkyFunctions.isSkyFunction(SkyFunctions.PACKAGE);
+
+  private static final Predicate<SkyKey> IS_EXTERNAL_PACKAGE =
+      SkyFunctions.isSkyFunction(SkyFunctions.EXTERNAL_PACKAGE);
+
+  private static final Predicate<SkyKey> IS_WORKSPACE_FILE =
+      SkyFunctions.isSkyFunction(WorkspaceFileValue.WORKSPACE_FILE);
+
   private static void requestRepoDefinitions(
       ExtendedEventHandler eventHandler, Iterable<SkyKey> repos) {
     for (SkyKey repo : repos) {
@@ -85,21 +101,33 @@ public boolean maybeReportCycle(
     //                   |___________________|___|
     // TODO(andreisolo): Figure out how to detect and print this kind of cycles more specifically.
     if (Iterables.all(
-        cycle,
-        Predicates.or(
-            IS_REPOSITORY_DIRECTORY,
-            IS_PACKAGE_LOOKUP,
-            IS_REPO_RULE,
-            IS_EXTENSION_IMPL,
-            IS_BZL_LOAD,
-            IS_CONTAINING_PACKAGE))) {
+            cycle,
+            Predicates.or(
+                IS_REPOSITORY_DIRECTORY,
+                IS_PACKAGE_LOOKUP,
+                IS_REPO_RULE,
+                IS_EXTENSION_IMPL,
+                IS_BZL_LOAD,
+                IS_CONTAINING_PACKAGE,
+                IS_REPO_MAPPING,
+                IS_MODULE_EXTENSION_REPO_MAPPING_ENTRIES,
+                IS_PACKAGE,
+                IS_EXTERNAL_PACKAGE,
+                IS_WORKSPACE_FILE))
+        && Iterables.any(cycle, Predicates.or(IS_REPO_RULE, IS_EXTENSION_IMPL))) {
       StringBuilder cycleMessage =
           new StringBuilder(
               "Circular definition of repositories generated by module extensions and/or .bzl"
                   + " files:");
       Iterable<SkyKey> repos =
           Iterables.filter(
-              cycle, Predicates.or(IS_REPOSITORY_DIRECTORY, IS_EXTENSION_IMPL, IS_BZL_LOAD));
+              cycle,
+              Predicates.or(
+                  IS_REPOSITORY_DIRECTORY,
+                  IS_EXTENSION_IMPL,
+                  IS_BZL_LOAD,
+                  IS_REPO_MAPPING,
+                  IS_WORKSPACE_FILE));
       Function<Object, String> printer =
           rawInput -> {
             SkyKey input = (SkyKey) rawInput;
@@ -110,6 +138,14 @@ public boolean maybeReportCycle(
               return String.format(
                   "extension '%s' defined in %s",
                   id.getExtensionName(), id.getBzlFileLabel().getCanonicalForm());
+            } else if (input.argument() instanceof RepositoryMappingValue.Key) {
+              var key = (RepositoryMappingValue.Key) input.argument();
+              if (key == RepositoryMappingValue.KEY_FOR_ROOT_MODULE_WITHOUT_WORKSPACE_REPOS) {
+                return "repository mapping of @@ without WORKSPACE repos";
+              }
+              return String.format("repository mapping of %s", key.repoName());
+            } else if (input.argument() instanceof WorkspaceFileValue.WorkspaceFileKey) {
+              return "WORKSPACE file";
             } else {
               Preconditions.checkArgument(input.argument() instanceof BzlLoadValue.Key);
               return ((BzlLoadValue.Key) input.argument()).getLabel().toString();