Add incompatible_stop_exporting_build_file_path

to guard removing `ctx.build_file_path`

PiperOrigin-RevId: 608766817
Change-Id: Ib3a636a30aa5fbb0c369f9eabef56f8dfb869049

src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkRuleContext.java

@@ -994,10 +994,23 @@ public Artifact getVolatileWorkspaceStatus() throws InterruptedException, EvalEx
   @Override
   public String getBuildFileRelativePath() throws EvalException {
     checkMutable("build_file_path");
+    checkDeprecated("ctx.label.package + '/BUILD'", "ctx.build_file_path", getStarlarkSemantics());
+
     Package pkg = ruleContext.getRule().getPackage();
     return pkg.getSourceRoot().get().relativize(pkg.getBuildFile().getPath()).getPathString();
   }
 
+  private static void checkDeprecated(String newApi, String oldApi, StarlarkSemantics semantics)
+      throws EvalException {
+    if (semantics.getBool(BuildLanguageOptions.INCOMPATIBLE_STOP_EXPORTING_BUILD_FILE_PATH)) {
+      throw Starlark.errorf(
+          "Use %s instead of %s.\n"
+              + "Use --incompatible_stop_exporting_build_file_path=false to temporarily disable"
+              + " this check.",
+          newApi, oldApi);
+    }
+  }
+
   @Override
   public String expandLocation(
       String input, Sequence<?> targets, boolean shortPaths, StarlarkThread thread)

src/main/java/com/google/devtools/build/lib/packages/semantics/BuildLanguageOptions.java

@@ -245,6 +245,17 @@ public final class BuildLanguageOptions extends OptionsBase {
               + " immutable view objects instead of mutable dicts.")
   public boolean incompatibleExistingRulesImmutableView;
 
+  @Option(
+      name = "incompatible_stop_exporting_build_file_path",
+      defaultValue = "false",
+      documentationCategory = OptionDocumentationCategory.STARLARK_SEMANTICS,
+      effectTags = {OptionEffectTag.LOADING_AND_ANALYSIS},
+      metadataTags = {OptionMetadataTag.INCOMPATIBLE_CHANGE},
+      help =
+          "If set to true, deprecated ctx.build_file_path will not be available. ctx.label.package"
+              + " + '/BUILD' can be used instead.")
+  public boolean incompatibleStopExportingBuildFilePath;
+
   @Option(
       name = "experimental_google_legacy_api",
       defaultValue = "false",
@@ -829,6 +840,8 @@ public StarlarkSemantics toStarlarkSemantics() {
             .setBool(EXPERIMENTAL_RULE_EXTENSION_API, experimentalRuleExtensionApi)
             .setBool(SEPARATE_ASPECT_DEPS, separateAspectDeps)
             .setBool(INCOMPATIBLE_ENABLE_DEPRECATED_LABEL_APIS, enableDeprecatedLabelApis)
+            .setBool(
+                INCOMPATIBLE_STOP_EXPORTING_BUILD_FILE_PATH, incompatibleStopExportingBuildFilePath)
             .build();
     return INTERNER.intern(semantics);
   }
@@ -925,7 +938,8 @@ public StarlarkSemantics toStarlarkSemantics() {
   public static final String SEPARATE_ASPECT_DEPS = "+separate_aspect_deps";
   public static final String INCOMPATIBLE_ENABLE_DEPRECATED_LABEL_APIS =
       "+incompatible_enable_deprecated_label_apis";
-
+  public static final String INCOMPATIBLE_STOP_EXPORTING_BUILD_FILE_PATH =
+      "-incompatible_stop_exporting_build_file_path";
   // non-booleans
   public static final StarlarkSemantics.Key<String> EXPERIMENTAL_BUILTINS_BZL_PATH =
       new StarlarkSemantics.Key<>("experimental_builtins_bzl_path", "%bundled%");

src/test/java/com/google/devtools/build/lib/starlark/StarlarkRuleContextTest.java

@@ -3528,6 +3528,33 @@ public void testBuildFilePath() throws Exception {
     assertThat(result).isEqualTo("bar/BUILD");
   }
 
+  @Test
+  public void testStopExportingBuildFilePath() throws Exception {
+    scratch.file("/foo/WORKSPACE");
+    scratch.file("/foo/bar/BUILD", "genrule(name = 'baz', cmd = 'dummy_cmd', outs = ['a.txt'])");
+
+    scratch.overwriteFile(
+        "WORKSPACE",
+        new ImmutableList.Builder<String>()
+            .addAll(analysisMock.getWorkspaceContents(mockToolsConfig))
+            .add("local_repository(name='foo', path='/foo')")
+            .build());
+
+    invalidatePackages(false);
+    setBuildLanguageOptions("--incompatible_stop_exporting_build_file_path");
+
+    setRuleContext(createRuleContext("@foo//bar:baz"));
+
+    EvalException evalException =
+        assertThrows(EvalException.class, () -> ev.eval("ruleContext.build_file_path"));
+    assertThat(evalException)
+        .hasMessageThat()
+        .isEqualTo(
+            "Use ctx.label.package + '/BUILD' instead of ctx.build_file_path.\nUse"
+                + " --incompatible_stop_exporting_build_file_path=false to temporarily disable this"
+                + " check.");
+  }
+
   @Test
   public void testNoToolchainContext() throws Exception {
     // Build setting rules do not have a toolchain context, as they are part of the configuration.