initial commit

common/utils/src/main/resources/error/error-conditions.json

@@ -1028,6 +1028,12 @@
           "cannot find a static method <methodName> that matches the argument types in <className>."
         ]
       },
+      "UNSUPPORTED_CASE_WHEN_CLAUSE" : {
+        "message" : [
+          "The CASE WHEN clause of type <clause> is not supported."
+        ],
+        "sqlState" : "42601"
+      },
       "UNSUPPORTED_INPUT_TYPE" : {
         "message" : [
           "The input of <functionName> can't be <dataType> type data."

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/parser/AstBuilder.scala

@@ -2932,6 +2932,10 @@ class AstBuilder extends DataTypeAstBuilder
     val branches = ctx.whenClause.asScala.map { wCtx =>
       (expression(wCtx.condition), expression(wCtx.result))
     }
+    branches.foreach(
+      branch => if (branch._1.isInstanceOf[LambdaFunction]) throw new ParseException(
+        "UNSUPPORTED_CASE_WHEN_CLAUSE", Map("clause" -> "LambdaFunction"), ctx)
+    )
     CaseWhen(branches.toSeq, Option(ctx.elseExpression).map(expression))
   }
 

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/PlanParserSuite.scala

@@ -1973,4 +1973,18 @@ class PlanParserSuite extends AnalysisTest {
     assert(unresolvedRelation2.options == CaseInsensitiveStringMap.empty)
     assert(unresolvedRelation2.isStreaming)
   }
+
+  test("SPARK-49976: Disable lambda functions as case when clauses") {
+    val query = "select (case when a->b = true then 1 else 0 end)"
+    checkError(
+      exception = parseException(query),
+      condition = "UNSUPPORTED_CASE_WHEN_CLAUSE",
+      sqlState = Some("42601"),
+      parameters = Map("clause" -> "LambdaFunction"),
+      context = ExpectedContext(
+        fragment = "case when a->b = true then 1 else 0 end",
+        start = 8,
+        stop = 46)
+    )
+  }
 }