## Coverage Report

#### Created: 2025-11-22 06:00

next uncovered line (L), next uncovered region (R), next uncovered branch (B)

    /Users/andrewlamb/Software/datafusion/datafusion/expr/src/type_coercion/other.rs

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    // Licensed to the Apache Software Foundation (ASF) under one
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    // or more contributor license agreements.  See the NOTICE file
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    // distributed with this work for additional information
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    // regarding copyright ownership.  The ASF licenses this file
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    // to you under the Apache License, Version 2.0 (the
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    // "License"); you may not use this file except in compliance
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    // with the License.  You may obtain a copy of the License at
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    //
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    //   http://www.apache.org/licenses/LICENSE-2.0
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    //
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    // Unless required by applicable law or agreed to in writing,
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    // software distributed under the License is distributed on an
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    // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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    // KIND, either express or implied.  See the License for the
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    // specific language governing permissions and limitations
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    // under the License.
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    use arrow::datatypes::DataType;
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    use super::binary::comparison_coercion;
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    /// Attempts to coerce the types of `list_types` to be comparable with the
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    /// `expr_type`.
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    /// Returns the common data type for `expr_type` and `list_types`
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    pub fn get_coerce_type_for_list(
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        expr_type: &DataType,
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        list_types: &[DataType],
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    ) -> Option<DataType> {
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        list_types
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            .iter()
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            .try_fold(expr_type.clone(), |left_type, right_type| {
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                comparison_coercion(&left_type, right_type)
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    0
            })
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    }
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    /// Find a common coerceable type for all `when_or_then_types` as well
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    /// and the `case_or_else_type`, if specified.
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    /// Returns the common data type for `when_or_then_types` and `case_or_else_type`
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    pub fn get_coerce_type_for_case_expression(
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        when_or_then_types: &[DataType],
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        case_or_else_type: Option<&DataType>,
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    ) -> Option<DataType> {
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        let case_or_else_type = match case_or_else_type {
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            None => when_or_then_types[0].clone(),
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            Some(data_type) => data_type.clone(),
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        };
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        when_or_then_types
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            .iter()
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            .try_fold(case_or_else_type, |left_type, right_type| {
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                // TODO: now just use the `equal` coercion rule for case when. If find the issue, and
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                // refactor again.
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                comparison_coercion(&left_type, right_type)
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            })
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    }