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

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

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

diff --git a/src/test/java/com/google/devtools/build/lib/syntax/SkylarkNestedSetTest.java b/src/test/java/com/google/devtools/build/lib/syntax/SkylarkNestedSetTest.java
index 8fab5eb..4a4cc0f 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/SkylarkNestedSetTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/SkylarkNestedSetTest.java
@@ -44,6 +44,17 @@
   }
 
   @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')");
     assertThat(lookup("s")).isInstanceOf(SkylarkNestedSet.class);

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

diff --git a/src/test/java/com/google/devtools/build/lib/syntax/util/EvaluationTestCase.java b/src/test/java/com/google/devtools/build/lib/syntax/util/EvaluationTestCase.java
index d76e2eb..0aa9b0a 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/util/EvaluationTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/util/EvaluationTestCase.java
@@ -92,19 +92,25 @@
   }
 
   /**
-   * 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

diff --git a/src/test/java/com/google/devtools/build/lib/testutil/TestMode.java b/src/test/java/com/google/devtools/build/lib/testutil/TestMode.java
index 21132c2..12b8e6b 100644
--- a/src/test/java/com/google/devtools/build/lib/testutil/TestMode.java
+++ b/src/test/java/com/google/devtools/build/lib/testutil/TestMode.java
@@ -17,19 +17,30 @@
 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();
         }
       };
@@ -37,13 +48,16 @@
   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;
 }