[SPARK-48229][SQL] Add collation support for inputFile expressions

### What changes were proposed in this pull request?
Introduce collation awareness for inputFile expressions: input_file_name.

### Why are the changes needed?
Add collation support for inputFile expressions in Spark.

### Does this PR introduce _any_ user-facing change?
Yes, users should now be able to use collated strings within arguments for inputFile functions: input_file_name.

### How was this patch tested?
E2e sql tests.

### Was this patch authored or co-authored using generative AI tooling?
No.

Closes #46503 from uros-db/input-file-block.

Authored-by: Uros Bojanic <157381213+uros-db@users.noreply.github.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

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

@@ -21,7 +21,8 @@ import org.apache.spark.rdd.InputFileBlockHolder
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, CodeGenerator, ExprCode, FalseLiteral}
 import org.apache.spark.sql.catalyst.expressions.codegen.Block._
-import org.apache.spark.sql.types.{DataType, LongType, StringType}
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.types.{DataType, LongType}
 import org.apache.spark.unsafe.types.UTF8String
 
 // scalastyle:off whitespace.end.of.line
@@ -39,7 +40,7 @@ case class InputFileName() extends LeafExpression with Nondeterministic {
 
   override def nullable: Boolean = false
 
-  override def dataType: DataType = StringType
+  override def dataType: DataType = SQLConf.get.defaultStringType
 
   override def prettyName: String = "input_file_name"
 

sql/core/src/test/scala/org/apache/spark/sql/CollationSQLExpressionsSuite.scala

@@ -1275,6 +1275,23 @@ class CollationSQLExpressionsSuite
     })
   }
 
+  test("Support InputFileName expression with collation") {
+    // Supported collations
+    Seq("UTF8_BINARY", "UTF8_BINARY_LCASE", "UNICODE", "UNICODE_CI").foreach(collationName => {
+      val query =
+        s"""
+           |select input_file_name()
+           |""".stripMargin
+      // Result
+      withSQLConf(SqlApiConf.DEFAULT_COLLATION -> collationName) {
+        val testQuery = sql(query)
+        checkAnswer(testQuery, Row(""))
+        val dataType = StringType(collationName)
+        assert(testQuery.schema.fields.head.dataType.sameType(dataType))
+      }
+    })
+  }
+
   // TODO: Add more tests for other SQL expressions
 
 }