fix: Fix scalar broadcast for to_timestamp() (#20224)

When to_timestamp() was invoked with a scalar Float64 and an array of
strings, the previous coding neglected to broadcast the scalar to the
array properly when producing the return value. That is, a query like
`SELECT to_timestamp(123.5, t.x) FROM t` would result in:

    Internal error: UDF to_timestamp returned a different number of rows
    than expected

## Which issue does this PR close?

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- Closes #20223

## Rationale for this change

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## Are these changes tested?

Yes, added SLT.

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datafusion/functions/src/datetime/to_timestamp.rs

@@ -430,27 +430,56 @@ impl ScalarUDFImpl for ToTimestampFunc {
                 .cast_to(&Timestamp(Second, None), None)?
                 .cast_to(&Timestamp(Nanosecond, tz), None),
             Null | Timestamp(_, _) => args[0].cast_to(&Timestamp(Nanosecond, tz), None),
-            Float16 => {
-                let arr = args[0].to_array(1)?;
-                let f16_arr = downcast_arg!(&arr, Float16Array);
-                let result: TimestampNanosecondArray =
-                    f16_arr.unary(|x| (x.to_f64() * 1_000_000_000.0) as i64);
-                Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
-            }
-            Float32 => {
-                let arr = args[0].to_array(1)?;
-                let f32_arr = downcast_arg!(&arr, Float32Array);
-                let result: TimestampNanosecondArray =
-                    f32_arr.unary(|x| (x as f64 * 1_000_000_000.0) as i64);
-                Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
-            }
-            Float64 => {
-                let arr = args[0].to_array(1)?;
-                let f64_arr = downcast_arg!(&arr, Float64Array);
-                let result: TimestampNanosecondArray =
-                    f64_arr.unary(|x| (x * 1_000_000_000.0) as i64);
-                Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
-            }
+            Float16 => match &args[0] {
+                ColumnarValue::Scalar(ScalarValue::Float16(value)) => {
+                    let timestamp_nanos =
+                        value.map(|v| (v.to_f64() * 1_000_000_000.0) as i64);
+                    Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(
+                        timestamp_nanos,
+                        tz,
+                    )))
+                }
+                ColumnarValue::Array(arr) => {
+                    let f16_arr = downcast_arg!(arr, Float16Array);
+                    let result: TimestampNanosecondArray =
+                        f16_arr.unary(|x| (x.to_f64() * 1_000_000_000.0) as i64);
+                    Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
+                }
+                _ => exec_err!("Invalid Float16 value for to_timestamp"),
+            },
+            Float32 => match &args[0] {
+                ColumnarValue::Scalar(ScalarValue::Float32(value)) => {
+                    let timestamp_nanos =
+                        value.map(|v| (v as f64 * 1_000_000_000.0) as i64);
+                    Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(
+                        timestamp_nanos,
+                        tz,
+                    )))
+                }
+                ColumnarValue::Array(arr) => {
+                    let f32_arr = downcast_arg!(arr, Float32Array);
+                    let result: TimestampNanosecondArray =
+                        f32_arr.unary(|x| (x as f64 * 1_000_000_000.0) as i64);
+                    Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
+                }
+                _ => exec_err!("Invalid Float32 value for to_timestamp"),
+            },
+            Float64 => match &args[0] {
+                ColumnarValue::Scalar(ScalarValue::Float64(value)) => {
+                    let timestamp_nanos = value.map(|v| (v * 1_000_000_000.0) as i64);
+                    Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond(
+                        timestamp_nanos,
+                        tz,
+                    )))
+                }
+                ColumnarValue::Array(arr) => {
+                    let f64_arr = downcast_arg!(arr, Float64Array);
+                    let result: TimestampNanosecondArray =
+                        f64_arr.unary(|x| (x * 1_000_000_000.0) as i64);
+                    Ok(ColumnarValue::Array(Arc::new(result.with_timezone_opt(tz))))
+                }
+                _ => exec_err!("Invalid Float64 value for to_timestamp"),
+            },
             Decimal32(_, _) | Decimal64(_, _) | Decimal256(_, _) => {
                 let arg = args[0].cast_to(&Decimal128(38, 9), None)?;
                 decimal128_to_timestamp_nanos(&arg, tz)

datafusion/sqllogictest/test_files/datetime/arith_date_time.slt

@@ -113,4 +113,3 @@ SELECT '2001-09-28'::date / '03:00'::time
 
 query error Invalid timestamp arithmetic operation
 SELECT '2001-09-28'::date % '03:00'::time
-

datafusion/sqllogictest/test_files/datetime/arith_timestamp_duration.slt

@@ -144,4 +144,4 @@ query error Invalid timestamp arithmetic operation
 SELECT '2001-09-28T01:00:00'::timestamp % arrow_cast(12345, 'Duration(Second)');
 
 query error Invalid timestamp arithmetic operation
-SELECT '2001-09-28T01:00:00'::timestamp / arrow_cast(12345, 'Duration(Second)');
+SELECT '2001-09-28T01:00:00'::timestamp / arrow_cast(12345, 'Duration(Second)');

datafusion/sqllogictest/test_files/datetime/timestamps.slt

@@ -5328,3 +5328,33 @@ drop table ts_data_secs
 
 statement ok
 drop table ts_data_micros_kolkata
+
+##########
+## Test to_timestamp with scalar float inputs
+##########
+
+statement ok
+create table test_to_timestamp_scalar(id int, name varchar) as values
+  (1, 'foo'),
+  (2, 'bar');
+
+query P
+SELECT to_timestamp(123.5, name) FROM test_to_timestamp_scalar ORDER BY id;
+----
+1970-01-01T00:02:03.500
+1970-01-01T00:02:03.500
+
+query P
+SELECT to_timestamp(456.789::float, name) FROM test_to_timestamp_scalar ORDER BY id;
+----
+1970-01-01T00:07:36.789001464
+1970-01-01T00:07:36.789001464
+
+query P
+SELECT to_timestamp(arrow_cast(100.5, 'Float16'), name) FROM test_to_timestamp_scalar ORDER BY id;
+----
+1970-01-01T00:01:40.500
+1970-01-01T00:01:40.500
+
+statement ok
+drop table test_to_timestamp_scalar

datafusion/sqllogictest/test_files/limit.slt

@@ -871,4 +871,4 @@ DROP TABLE test_limit_with_partitions;
 
 # Tear down src_table table:
 statement ok
-DROP TABLE src_table;
+DROP TABLE src_table;

datafusion/sqllogictest/test_files/limit_single_row_batches.slt

@@ -19,4 +19,4 @@ SELECT COUNT(*) FROM (SELECT i FROM filter_limit WHERE i <> 0 LIMIT 1);
 1
 
 statement ok
-DROP TABLE filter_limit;
+DROP TABLE filter_limit;

datafusion/sqllogictest/test_files/spark/collection/size.slt

@@ -129,4 +129,3 @@ SELECT size(column1) FROM VALUES (map(['a'], [1])), (map(['a','b'], [1,2])), (NU
 1
 2
 -1
-

datafusion/sqllogictest/test_files/spark/datetime/time_trunc.slt

@@ -71,4 +71,3 @@ NULL
 # incorrect format
 query error DataFusion error: Optimizer rule 'simplify_expressions' failed\ncaused by\nError during planning: The format argument of `TIME_TRUNC` must be one of: hour, minute, second, millisecond, microsecond
 SELECT time_trunc('test', '09:32:05.123456'::time);
-

datafusion/sqllogictest/test_files/spark/datetime/trunc.slt

@@ -90,4 +90,3 @@ SELECT trunc('2009-02-12'::date, NULL::string);
 # incorrect format
 query error DataFusion error: Optimizer rule 'simplify_expressions' failed\ncaused by\nError during planning: The format argument of `TRUNC` must be one of: year, yy, yyyy, month, mm, mon, day, week, quarter.
 SELECT trunc('2009-02-12'::date, 'test'::string);
-

datafusion/sqllogictest/test_files/struct.slt

@@ -1666,4 +1666,4 @@ order by id;
 3 2 150
 
 statement ok
-drop table t_agg_window;
+drop table t_agg_window;

datafusion/sqllogictest/test_files/truncate.slt

@@ -82,4 +82,4 @@ logical_plan
 physical_plan_error
 01)TRUNCATE operation on table 't1'
 02)caused by
-03)This feature is not implemented: TRUNCATE not supported for Base table
+03)This feature is not implemented: TRUNCATE not supported for Base table