Implement a flag to deprecate old constructor for depsets (set)

Usage: --incompatible_depset_constructor=true (the default value is false).
PiperOrigin-RevId: 154971526

src/main/java/com/google/devtools/build/lib/syntax/BazelLibrary.java

@@ -119,12 +119,21 @@ public SkylarkNestedSet invoke(Object items, String order, Location loc)
         doc = "Same as for <a href=\"#depset\">depset</a>."
       )
     },
-    useLocation = true
+    useLocation = true,
+    useEnvironment = true
   )
   private static final BuiltinFunction set =
       new BuiltinFunction("set") {
-        public SkylarkNestedSet invoke(Object items, String order, Location loc)
+        public SkylarkNestedSet invoke(Object items, String order, Location loc, Environment env)
             throws EvalException {
+          if (env.getSemantics().incompatibleDepsetConstructor) {
+            throw new EvalException(
+                loc,
+                "The `set` constructor for depsets is deprecated and will be removed. Please use "
+                    + "the `depset` constructor instead. You can temporarily enable the "
+                    + "deprecated `set` constructor by passing the flag "
+                    + "--incompatible_depset_constructor=false");
+          }
           try {
             return new SkylarkNestedSet(Order.parse(order), items, loc);
           } catch (IllegalArgumentException ex) {

src/main/java/com/google/devtools/build/lib/syntax/SkylarkSemanticsOptions.java

@@ -42,4 +42,12 @@ public class SkylarkSemanticsOptions extends OptionsBase implements Serializable
       optionUsageRestrictions = OptionUsageRestrictions.UNDOCUMENTED
   )
   public boolean skylarkFlagTestCanary;
+
+  @Option(
+    name = "incompatible_depset_constructor",
+    defaultValue = "false",
+    category = "incompatible changes",
+    help = "If set to true, disables the deprecated `set` constructor for depsets."
+  )
+  public boolean incompatibleDepsetConstructor;
 }

src/test/java/com/google/devtools/build/lib/syntax/SkylarkNestedSetTest.java

@@ -43,6 +43,17 @@ public void testLegacyConstructor() throws Exception {
     assertThat(s.getSet(Object.class)).containsExactly(1, 2, 3);
   }
 
+  @Test
+  public void testLegacyConstructorDeprecation() throws Exception {
+    env = newEnvironmentWithSkylarkOptions("--incompatible_depset_constructor=true");
+    try {
+      eval("s = set([1, 2, 3], order='postorder')");
+      Assert.fail("`set` should have failed");
+    } catch (EvalException e) {
+      assertThat(e.getMessage()).contains("The `set` constructor for depsets is deprecated");
+    }
+  }
+
   @Test
   public void testConstructor() throws Exception {
     eval("s = depset(order='default')");

src/test/java/com/google/devtools/build/lib/syntax/util/EvaluationTestCase.java

@@ -92,19 +92,25 @@ public Environment newSkylarkEnvironment() {
   }
 
   /**
-   * Creates a new Environment suitable for the test case. Subclasses may override it
-   * to fit their purpose and e.g. call newBuildEnvironment or newSkylarkEnvironment;
-   * or they may play with the testMode to run tests in either or both kinds of Environment.
-   * Note that all Environment-s may share the same Mutability, so don't close it.
+   * Creates a new Environment suitable for the test case. Subclasses may override it to fit their
+   * purpose and e.g. call newBuildEnvironment or newSkylarkEnvironment; or they may play with the
+   * testMode to run tests in either or both kinds of Environment. Note that all Environment-s may
+   * share the same Mutability, so don't close it.
+   *
    * @return a fresh Environment.
    */
   public Environment newEnvironment() throws Exception {
+    return newEnvironmentWithSkylarkOptions();
+  }
+
+  protected Environment newEnvironmentWithSkylarkOptions(String... skylarkOptions)
+      throws Exception {
     if (testMode == null) {
       throw new IllegalArgumentException(
           "TestMode is null. Please set a Testmode via setMode() or set the "
               + "Environment manually by overriding newEnvironment()");
     }
-    return testMode.createEnvironment(getEventHandler(), null);
+    return testMode.createEnvironment(getEventHandler(), skylarkOptions);
   }
 
   /**

src/test/java/com/google/devtools/build/lib/testutil/TestMode.java

@@ -17,33 +17,47 @@
 import com.google.devtools.build.lib.syntax.BazelLibrary;
 import com.google.devtools.build.lib.syntax.Environment;
 import com.google.devtools.build.lib.syntax.Mutability;
+import com.google.devtools.build.lib.syntax.SkylarkSemanticsOptions;
+import com.google.devtools.common.options.OptionsParser;
 
 /**
  * Describes a particular testing mode by determining how the
  * appropriate {@code Environment} has to be created
  */
 public abstract class TestMode {
+  private static SkylarkSemanticsOptions parseSkylarkSemanticsOptions(String... skylarkOptions)
+      throws Exception {
+    OptionsParser parser = OptionsParser.newOptionsParser(SkylarkSemanticsOptions.class);
+    parser.parse(skylarkOptions);
+    return parser.getOptions(SkylarkSemanticsOptions.class);
+  }
+
   public static final TestMode BUILD =
       new TestMode() {
         @Override
-        public Environment createEnvironment(EventHandler eventHandler, Environment environment) {
+        public Environment createEnvironment(EventHandler eventHandler, String... skylarkOptions)
+            throws Exception {
           return Environment.builder(Mutability.create("build test"))
-              .setGlobals(environment == null ? BazelLibrary.GLOBALS : environment.getGlobals())
+              .setGlobals(BazelLibrary.GLOBALS)
               .setEventHandler(eventHandler)
+              .setSemantics(TestMode.parseSkylarkSemanticsOptions(skylarkOptions))
               .build();
         }
       };
 
   public static final TestMode SKYLARK =
       new TestMode() {
         @Override
-        public Environment createEnvironment(EventHandler eventHandler, Environment environment) {
+        public Environment createEnvironment(EventHandler eventHandler, String... skylarkOptions)
+            throws Exception {
           return Environment.builder(Mutability.create("skylark test"))
-              .setGlobals(environment == null ? BazelLibrary.GLOBALS : environment.getGlobals())
+              .setGlobals(BazelLibrary.GLOBALS)
               .setEventHandler(eventHandler)
+              .setSemantics(TestMode.parseSkylarkSemanticsOptions(skylarkOptions))
               .build();
         }
       };
 
-  public abstract Environment createEnvironment(EventHandler eventHandler, Environment environment);
+  public abstract Environment createEnvironment(EventHandler eventHandler, String... skylarkOptions)
+      throws Exception;
 }