[SPARK-29100][SQL] Fix compilation error in codegen with switch from InSet expression

### What changes were proposed in this pull request?

When InSet generates Java switch-based code, if the input set is empty, we don't generate switch condition, but a simple expression that is default case of original switch.

### Why are the changes needed?

SPARK-26205 adds an optimization to InSet that generates Java switch condition for certain cases. When the given set is empty, it is possibly that codegen causes compilation error:

```
[info] - SPARK-29100: InSet with empty input set *** FAILED *** (58 milliseconds)
[info]   Code generation of input[0, int, true] INSET () failed:
[info]   org.codehaus.janino.InternalCompilerException: failed to compile: org.codehaus.janino.InternalCompilerException: Compiling "GeneratedClass" in "generated.java": Compiling "apply(java.lang.Object _i)"; apply(java.lang.Object _i): Operand stack inconsistent at offset 45: Previous size 0, now 1
[info]   org.codehaus.janino.InternalCompilerException: failed to compile: org.codehaus.janino.InternalCompilerException: Compiling "GeneratedClass" in "generated.java": Compiling "apply(java.lang.Object _i)"; apply(java.lang.Object _i): Operand stack inconsistent at offset 45: Previous size 0, now 1
[info]         at org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator$.org$apache$spark$sql$catalyst$expressions$codegen$CodeGenerator$$doCompile(CodeGenerator.scala:1308)
[info]         at org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator$$anon$1.load(CodeGenerator.scala:1386)
[info]         at org.apache.spark.sql.catalyst.expressions.codegen.CodeGenerator$$anon$1.load(CodeGenerator.scala:1383)
```

### Does this PR introduce any user-facing change?

Yes. Previously, when users have InSet against an empty set, generated code causes compilation error. This patch fixed it.

### How was this patch tested?

Unit test added.

Closes #25806 from viirya/SPARK-29100.

Authored-by: Liang-Chi Hsieh <viirya@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

Author: viirya

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala

@@ -457,17 +457,25 @@ case class InSet(child: Expression, hset: Set[Any]) extends UnaryExpression with
           break;
        """)
 
+    val switchCode = if (caseBranches.size > 0) {
+      code"""
+        switch (${valueGen.value}) {
+          ${caseBranches.mkString("\n")}
+          default:
+            ${ev.isNull} = $hasNull;
+        }
+       """
+    } else {
+      s"${ev.isNull} = $hasNull;"
+    }
+
     ev.copy(code =
       code"""
         ${valueGen.code}
         ${CodeGenerator.JAVA_BOOLEAN} ${ev.isNull} = ${valueGen.isNull};
         ${CodeGenerator.JAVA_BOOLEAN} ${ev.value} = false;
         if (!${valueGen.isNull}) {
-          switch (${valueGen.value}) {
-            ${caseBranches.mkString("\n")}
-            default:
-              ${ev.isNull} = $hasNull;
-          }
+          $switchCode
         }
        """)
   }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/PredicateSuite.scala

@@ -560,4 +560,10 @@ class PredicateSuite extends SparkFunSuite with ExpressionEvalHelper {
         assert(msg.contains("argument 1 requires boolean type"))
     }
   }
+
+  test("SPARK-29100: InSet with empty input set") {
+    val row = create_row(1)
+    val inSet = InSet(BoundReference(0, IntegerType, true), Set.empty)
+    checkEvaluation(inSet, false, row)
+  }
 }