Introduce flag --incompatible_no_kwargs_in_build_files

Implements https://github.com/bazelbuild/bazel/issues/8021

When it is enabled, **kwargs and *args are not allowed in BUILD files.
Without this flag, the ban on **kwarg and *args is not fully working.

RELNOTES: New flag `--incompatible_no_kwargs_in_build_files`. See https://github.com/bazelbuild/bazel/issues/8021
PiperOrigin-RevId: 243325744

src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java

diff --git a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
index 623206c..2b533f9 100644
--- a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
+++ b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
@@ -148,6 +148,7 @@
         "--incompatible_expand_directories=" + rand.nextBoolean(),
         "--incompatible_new_actions_api=" + rand.nextBoolean(),
         "--incompatible_no_attr_license=" + rand.nextBoolean(),
+        "--incompatible_no_kwargs_in_build_files=" + rand.nextBoolean(),
         "--incompatible_no_output_attr_default=" + rand.nextBoolean(),
         "--incompatible_no_support_tools_in_action_inputs=" + rand.nextBoolean(),
         "--incompatible_no_target_output_group=" + rand.nextBoolean(),
@@ -192,6 +193,7 @@
         .incompatibleExpandDirectories(rand.nextBoolean())
         .incompatibleNewActionsApi(rand.nextBoolean())
         .incompatibleNoAttrLicense(rand.nextBoolean())
+        .incompatibleNoKwargsInBuildFiles(rand.nextBoolean())
         .incompatibleNoOutputAttrDefault(rand.nextBoolean())
         .incompatibleNoSupportToolsInActionInputs(rand.nextBoolean())
         .incompatibleNoTargetOutputGroup(rand.nextBoolean())

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

diff --git a/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java b/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java
index df0847c..78700ea 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/EvaluationTest.java
@@ -708,4 +708,17 @@
     new BuildTest()
         .testIfErrorContains("*args arguments are not allowed in BUILD files", "func(*array)");
   }
+
+  @Test
+  public void testIncompatibleKwargsInBuildFiles() throws Exception {
+    new BuildTest("--incompatible_no_kwargs_in_build_files=true")
+        .testIfErrorContains(
+            "kwargs arguments are not allowed in BUILD files", "len(dict(**{'a': 1}))");
+
+    new BuildTest("--incompatible_no_kwargs_in_build_files=false")
+        .testStatement("len(dict(**{'a': 1}))", 1);
+
+    new SkylarkTest("--incompatible_no_kwargs_in_build_files")
+        .testStatement("len(dict(**{'a': 1}))", 1);
+  }
 }

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 88bc26e..365ba1d 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
@@ -201,7 +201,7 @@
       return BuildFileAST.eval(env, input);
     }
     BuildFileAST ast = BuildFileAST.parseString(env.getEventHandler(), input);
-    ValidationEnvironment.checkBuildSyntax(ast.getStatements(), env.getEventHandler());
+    ValidationEnvironment.checkBuildSyntax(ast.getStatements(), env.getEventHandler(), env);
     return ast.eval(env);
   }