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File Content: `OverlappingFieldsCanBeMerged.php`

<?php declare(strict_types=1);

namespace GraphQL\Validator\Rules;

use GraphQL\Error\Error;
use GraphQL\Language\AST\ArgumentNode;
use GraphQL\Language\AST\FieldNode;
use GraphQL\Language\AST\FragmentDefinitionNode;
use GraphQL\Language\AST\FragmentSpreadNode;
use GraphQL\Language\AST\InlineFragmentNode;
use GraphQL\Language\AST\Node;
use GraphQL\Language\AST\NodeKind;
use GraphQL\Language\AST\NodeList;
use GraphQL\Language\AST\SelectionSetNode;
use GraphQL\Language\Printer;
use GraphQL\Type\Definition\FieldDefinition;
use GraphQL\Type\Definition\InterfaceType;
use GraphQL\Type\Definition\ListOfType;
use GraphQL\Type\Definition\NonNull;
use GraphQL\Type\Definition\ObjectType;
use GraphQL\Type\Definition\Type;
use GraphQL\Utils\AST;
use GraphQL\Utils\PairSet;
use GraphQL\Validator\QueryValidationContext;

/**
 * ReasonOrReasons is recursive, but PHPStan does not support that.
 *
 * @phpstan-type ReasonOrReasons string|array<array{string, string|array<mixed>}>
 * @phpstan-type Conflict array{array{string, ReasonOrReasons}, array<int, FieldNode>, array<int, FieldNode>}
 * @phpstan-type FieldInfo array{Type|null, FieldNode, FieldDefinition|null}
 * @phpstan-type FieldMap array<string, array<int, FieldInfo>>
 */
class OverlappingFieldsCanBeMerged extends ValidationRule
{
    /**
     * A memoization for when two fragments are compared "between" each other for
     * conflicts. Two fragments may be compared many times, so memoizing this can
     * dramatically improve the performance of this validator.
     */
    protected PairSet $comparedFragmentPairs;

    /**
     * A cache for the "field map" and list of fragment names found in any given
     * selection set. Selection sets may be asked for this information multiple
     * times, so this improves the performance of this validator.
     *
     * @phpstan-var \SplObjectStorage<SelectionSetNode, array{FieldMap, array<int, string>}>
     */
    protected \SplObjectStorage $cachedFieldsAndFragmentNames;

    public function getVisitor(QueryValidationContext $context): array
    {
        $this->comparedFragmentPairs = new PairSet();
        $this->cachedFieldsAndFragmentNames = new \SplObjectStorage();

        return [
            NodeKind::SELECTION_SET => function (SelectionSetNode $selectionSet) use ($context): void {
                $conflicts = $this->findConflictsWithinSelectionSet(
                    $context,
                    $context->getParentType(),
                    $selectionSet
                );

                foreach ($conflicts as $conflict) {
                    [[$responseName, $reason], $fields1, $fields2] = $conflict;

                    $context->reportError(new Error(
                        static::fieldsConflictMessage($responseName, $reason),
                        array_merge($fields1, $fields2)
                    ));
                }
            },
        ];
    }

    /**
     * Find all conflicts found "within" a selection set, including those found
     * via spreading in fragments. Called when visiting each SelectionSet in the
     * GraphQL Document.
     *
     * @phpstan-return array<int, Conflict>
     *
     * @throws \Exception
     */
    protected function findConflictsWithinSelectionSet(
        QueryValidationContext $context,
        ?Type $parentType,
        SelectionSetNode $selectionSet
    ): array {
        [$fieldMap, $fragmentNames] = $this->getFieldsAndFragmentNames(
            $context,
            $parentType,
            $selectionSet
        );

        $conflicts = [];

        // (A) Find all conflicts "within" the fields of this selection set.
        // Note: this is the *only place* `collectConflictsWithin` is called.
        $this->collectConflictsWithin(
            $context,
            $conflicts,
            $fieldMap
        );

        $fragmentNamesLength = count($fragmentNames);
        if ($fragmentNamesLength !== 0) {
            // (B) Then collect conflicts between these fields and those represented by
            // each spread fragment name found.
            $comparedFragments = [];
            for ($i = 0; $i < $fragmentNamesLength; ++$i) {
                $this->collectConflictsBetweenFieldsAndFragment(
                    $context,
                    $conflicts,
                    $comparedFragments,
                    false,
                    $fieldMap,
                    $fragmentNames[$i]
                );
                // (C) Then compare this fragment with all other fragments found in this
                // selection set to collect conflicts between fragments spread together.
                // This compares each item in the list of fragment names to every other item
                // in that same list (except for itself).
                for ($j = $i + 1; $j < $fragmentNamesLength; ++$j) {
                    $this->collectConflictsBetweenFragments(
                        $context,
                        $conflicts,
                        false,
                        $fragmentNames[$i],
                        $fragmentNames[$j]
                    );
                }
            }
        }

        return $conflicts;
    }

    /**
     * Given a selection set, return the collection of fields (a mapping of response
     * name to field ASTs and definitions) as well as a list of fragment names
     * referenced via fragment spreads.
     *
     * @throws \Exception
     *
     * @return array{FieldMap, array<int, string>}
     */
    protected function getFieldsAndFragmentNames(
        QueryValidationContext $context,
        ?Type $parentType,
        SelectionSetNode $selectionSet
    ): array {
        if (! isset($this->cachedFieldsAndFragmentNames[$selectionSet])) {
            /** @phpstan-var FieldMap $astAndDefs */
            $astAndDefs = [];

            /** @var array<string, bool> $fragmentNames */
            $fragmentNames = [];

            $this->internalCollectFieldsAndFragmentNames(
                $context,
                $parentType,
                $selectionSet,
                $astAndDefs,
                $fragmentNames
            );

            return $this->cachedFieldsAndFragmentNames[$selectionSet] = [$astAndDefs, array_keys($fragmentNames)];
        }

        return $this->cachedFieldsAndFragmentNames[$selectionSet];
    }

    /**
     * Algorithm:.
     *
     * Conflicts occur when two fields exist in a query which will produce the same
     * response name, but represent differing values, thus creating a conflict.
     * The algorithm below finds all conflicts via making a series of comparisons
     * between fields. In order to compare as few fields as possible, this makes
     * a series of comparisons "within" sets of fields and "between" sets of fields.
     *
     * Given any selection set, a collection produces both a set of fields by
     * also including all inline fragments, as well as a list of fragments
     * referenced by fragment spreads.
     *
     * A) Each selection set represented in the document first compares "within" its
     * collected set of fields, finding any conflicts between every pair of
     * overlapping fields.
     * Note: This is the *only time* that a the fields "within" a set are compared
     * to each other. After this only fields "between" sets are compared.
     *
     * B) Also, if any fragment is referenced in a selection set, then a
     * comparison is made "between" the original set of fields and the
     * referenced fragment.
     *
     * C) Also, if multiple fragments are referenced, then comparisons
     * are made "between" each referenced fragment.
     *
     * D) When comparing "between" a set of fields and a referenced fragment, first
     * a comparison is made between each field in the original set of fields and
     * each field in the the referenced set of fields.
     *
     * E) Also, if any fragment is referenced in the referenced selection set,
     * then a comparison is made "between" the original set of fields and the
     * referenced fragment (recursively referring to step D).
     *
     * F) When comparing "between" two fragments, first a comparison is made between
     * each field in the first referenced set of fields and each field in the the
     * second referenced set of fields.
     *
     * G) Also, any fragments referenced by the first must be compared to the
     * second, and any fragments referenced by the second must be compared to the
     * first (recursively referring to step F).
     *
     * H) When comparing two fields, if both have selection sets, then a comparison
     * is made "between" both selection sets, first comparing the set of fields in
     * the first selection set with the set of fields in the second.
     *
     * I) Also, if any fragment is referenced in either selection set, then a
     * comparison is made "between" the other set of fields and the
     * referenced fragment.
     *
     * J) Also, if two fragments are referenced in both selection sets, then a
     * comparison is made "between" the two fragments.
     */

    /**
     * Given a reference to a fragment, return the represented collection of fields
     * as well as a list of nested fragment names referenced via fragment spreads.
     *
     * @param array<string, bool> $fragmentNames
     *
     * @phpstan-param FieldMap $astAndDefs
     *
     * @throws \Exception
     */
    protected function internalCollectFieldsAndFragmentNames(
        QueryValidationContext $context,
        ?Type $parentType,
        SelectionSetNode $selectionSet,
        array &$astAndDefs,
        array &$fragmentNames
    ): void {
        foreach ($selectionSet->selections as $selection) {
            switch (true) {
                case $selection instanceof FieldNode:
                    $fieldName = $selection->name->value;
                    $fieldDef = null;
                    if (
                        ($parentType instanceof ObjectType || $parentType instanceof InterfaceType)
                        && $parentType->hasField($fieldName)
                    ) {
                        $fieldDef = $parentType->getField($fieldName);
                    }

                    $responseName = $selection->alias->value ?? $fieldName;

                    $astAndDefs[$responseName] ??= [];
                    $astAndDefs[$responseName][] = [$parentType, $selection, $fieldDef];
                    break;
                case $selection instanceof FragmentSpreadNode:
                    $fragmentNames[$selection->name->value] = true;
                    break;
                case $selection instanceof InlineFragmentNode:
                    $typeCondition = $selection->typeCondition;
                    $inlineFragmentType = $typeCondition === null
                        ? $parentType
                        : AST::typeFromAST([$context->getSchema(), 'getType'], $typeCondition);

                    $this->internalCollectFieldsAndFragmentNames(
                        $context,
                        $inlineFragmentType,
                        $selection->selectionSet,
                        $astAndDefs,
                        $fragmentNames
                    );
                    break;
            }
        }
    }

    /**
     * Collect all Conflicts "within" one collection of fields.
     *
     * @param array<int, Conflict> $conflicts
     *
     * @phpstan-param FieldMap $fieldMap
     *
     * @throws \Exception
     */
    protected function collectConflictsWithin(
        QueryValidationContext $context,
        array &$conflicts,
        array $fieldMap
    ): void {
        // A field map is a keyed collection, where each key represents a response
        // name and the value at that key is a list of all fields which provide that
        // response name. For every response name, if there are multiple fields, they
        // must be compared to find a potential conflict.
        foreach ($fieldMap as $responseName => $fields) {
            // This compares every field in the list to every other field in this list
            // (except to itself). If the list only has one item, nothing needs to
            // be compared.
            $fieldsLength = count($fields);
            if ($fieldsLength <= 1) {
                continue;
            }

            for ($i = 0; $i < $fieldsLength; ++$i) {
                for ($j = $i + 1; $j < $fieldsLength; ++$j) {
                    $conflict = $this->findConflict(
                        $context,
                        false, // within one collection is never mutually exclusive
                        $responseName,
                        $fields[$i],
                        $fields[$j]
                    );
                    if ($conflict !== null) {
                        $conflicts[] = $conflict;
                    }
                }
            }
        }
    }

    /**
     * Determines if there is a conflict between two particular fields, including
     * comparing their sub-fields.
     *
     * @param array{Type|null, FieldNode, FieldDefinition|null} $field1
     * @param array{Type|null, FieldNode, FieldDefinition|null} $field2
     *
     * @phpstan-return Conflict|null
     *
     * @throws \Exception
     */
    protected function findConflict(
        QueryValidationContext $context,
        bool $parentFieldsAreMutuallyExclusive,
        string $responseName,
        array $field1,
        array $field2
    ): ?array {
        [$parentType1, $ast1, $def1] = $field1;
        [$parentType2, $ast2, $def2] = $field2;

        // If it is known that two fields could not possibly apply at the same
        // time, due to the parent types, then it is safe to permit them to diverge
        // in aliased field or arguments used as they will not present any ambiguity
        // by differing.
        // It is known that two parent types could never overlap if they are
        // different Object types. Interface or Union types might overlap - if not
        // in the current state of the schema, then perhaps in some future version,
        // thus may not safely diverge.
        $areMutuallyExclusive = $parentFieldsAreMutuallyExclusive
            || (
                $parentType1 !== $parentType2
                && $parentType1 instanceof ObjectType
                && $parentType2 instanceof ObjectType
            );

        // The return type for each field.
        $type1 = $def1 === null
            ? null
            : $def1->getType();
        $type2 = $def2 === null
            ? null
            : $def2->getType();

        if (! $areMutuallyExclusive) {
            // Two aliases must refer to the same field.
            $name1 = $ast1->name->value;
            $name2 = $ast2->name->value;
            if ($name1 !== $name2) {
                return [
                    [$responseName, "{$name1} and {$name2} are different fields"],
                    [$ast1],
                    [$ast2],
                ];
            }

            if (! $this->sameArguments($ast1->arguments, $ast2->arguments)) {
                return [
                    [$responseName, 'they have differing arguments'],
                    [$ast1],
                    [$ast2],
                ];
            }
        }

        if (
            $type1 !== null
            && $type2 !== null
            && $this->doTypesConflict($type1, $type2)
        ) {
            return [
                [$responseName, "they return conflicting types {$type1} and {$type2}"],
                [$ast1],
                [$ast2],
            ];
        }

        // Collect and compare sub-fields. Use the same "visited fragment names" list
        // for both collections so fields in a fragment reference are never
        // compared to themselves.
        $selectionSet1 = $ast1->selectionSet;
        $selectionSet2 = $ast2->selectionSet;
        if ($selectionSet1 !== null && $selectionSet2 !== null) {
            $conflicts = $this->findConflictsBetweenSubSelectionSets(
                $context,
                $areMutuallyExclusive,
                Type::getNamedType($type1),
                $selectionSet1,
                Type::getNamedType($type2),
                $selectionSet2
            );

            return $this->subfieldConflicts(
                $conflicts,
                $responseName,
                $ast1,
                $ast2
            );
        }

        return null;
    }

    /**
     * @param NodeList<ArgumentNode> $arguments1 keep
     * @param NodeList<ArgumentNode> $arguments2 keep
     */
    protected function sameArguments(NodeList $arguments1, NodeList $arguments2): bool
    {
        if (count($arguments1) !== count($arguments2)) {
            return false;
        }

        foreach ($arguments1 as $argument1) {
            $argument2 = null;
            foreach ($arguments2 as $argument) {
                if ($argument->name->value === $argument1->name->value) {
                    $argument2 = $argument;
                    break;
                }
            }

            if ($argument2 === null) {
                return false;
            }

            if (! $this->sameValue($argument1->value, $argument2->value)) {
                return false;
            }
        }

        return true;
    }

    protected function sameValue(Node $value1, Node $value2): bool
    {
        return Printer::doPrint($value1) === Printer::doPrint($value2);
    }

    /**
     * Two types conflict if both types could not apply to a value simultaneously.
     *
     * Composite types are ignored as their individual field types will be compared
     * later recursively. However, List and Non-Null types must match.
     */
    protected function doTypesConflict(Type $type1, Type $type2): bool
    {
        if ($type1 instanceof ListOfType) {
            return $type2 instanceof ListOfType
                ? $this->doTypesConflict($type1->getWrappedType(), $type2->getWrappedType())
                : true;
        }

        if ($type2 instanceof ListOfType) {
            return true;
        }

        if ($type1 instanceof NonNull) {
            return $type2 instanceof NonNull
                ? $this->doTypesConflict($type1->getWrappedType(), $type2->getWrappedType())
                : true;
        }

        if ($type2 instanceof NonNull) {
            return true;
        }

        if (Type::isLeafType($type1) || Type::isLeafType($type2)) {
            return $type1 !== $type2;
        }

        return false;
    }

    /**
     * Find all conflicts found between two selection sets, including those found
     * via spreading in fragments. Called when determining if conflicts exist
     * between the sub-fields of two overlapping fields.
     *
     * @throws \Exception
     *
     * @return array<int, Conflict>
     */
    protected function findConflictsBetweenSubSelectionSets(
        QueryValidationContext $context,
        bool $areMutuallyExclusive,
        ?Type $parentType1,
        SelectionSetNode $selectionSet1,
        ?Type $parentType2,
        SelectionSetNode $selectionSet2
    ): array {
        $conflicts = [];

        [$fieldMap1, $fragmentNames1] = $this->getFieldsAndFragmentNames(
            $context,
            $parentType1,
            $selectionSet1
        );
        [$fieldMap2, $fragmentNames2] = $this->getFieldsAndFragmentNames(
            $context,
            $parentType2,
            $selectionSet2
        );

        // (H) First, collect all conflicts between these two collections of field.
        $this->collectConflictsBetween(
            $context,
            $conflicts,
            $areMutuallyExclusive,
            $fieldMap1,
            $fieldMap2
        );

        // (I) Then collect conflicts between the first collection of fields and
        // those referenced by each fragment name associated with the second.
        $fragmentNames2Length = count($fragmentNames2);
        if ($fragmentNames2Length !== 0) {
            $comparedFragments = [];
            for ($j = 0; $j < $fragmentNames2Length; ++$j) {
                $this->collectConflictsBetweenFieldsAndFragment(
                    $context,
                    $conflicts,
                    $comparedFragments,
                    $areMutuallyExclusive,
                    $fieldMap1,
                    $fragmentNames2[$j]
                );
            }
        }

        // (I) Then collect conflicts between the second collection of fields and
        // those referenced by each fragment name associated with the first.
        $fragmentNames1Length = count($fragmentNames1);
        if ($fragmentNames1Length !== 0) {
            $comparedFragments = [];
            for ($i = 0; $i < $fragmentNames1Length; ++$i) {
                $this->collectConflictsBetweenFieldsAndFragment(
                    $context,
                    $conflicts,
                    $comparedFragments,
                    $areMutuallyExclusive,
                    $fieldMap2,
                    $fragmentNames1[$i]
                );
            }
        }

        // (J) Also collect conflicts between any fragment names by the first and
        // fragment names by the second. This compares each item in the first set of
        // names to each item in the second set of names.
        for ($i = 0; $i < $fragmentNames1Length; ++$i) {
            for ($j = 0; $j < $fragmentNames2Length; ++$j) {
                $this->collectConflictsBetweenFragments(
                    $context,
                    $conflicts,
                    $areMutuallyExclusive,
                    $fragmentNames1[$i],
                    $fragmentNames2[$j]
                );
            }
        }

        return $conflicts;
    }

    /**
     * Collect all Conflicts between two collections of fields. This is similar to,
     * but different from the `collectConflictsWithin` function above. This check
     * assumes that `collectConflictsWithin` has already been called on each
     * provided collection of fields. This is true because this validator traverses
     * each individual selection set.
     *
     * @phpstan-param array<int, Conflict> $conflicts
     * @phpstan-param FieldMap $fieldMap1
     * @phpstan-param FieldMap $fieldMap2
     *
     * @throws \Exception
     */
    protected function collectConflictsBetween(
        QueryValidationContext $context,
        array &$conflicts,
        bool $parentFieldsAreMutuallyExclusive,
        array $fieldMap1,
        array $fieldMap2
    ): void {
        // A field map is a keyed collection, where each key represents a response
        // name and the value at that key is a list of all fields which provide that
        // response name. For any response name which appears in both provided field
        // maps, each field from the first field map must be compared to every field
        // in the second field map to find potential conflicts.
        foreach ($fieldMap1 as $responseName => $fields1) {
            if (! isset($fieldMap2[$responseName])) {
                continue;
            }

            $fields2 = $fieldMap2[$responseName];
            $fields1Length = count($fields1);
            $fields2Length = count($fields2);
            for ($i = 0; $i < $fields1Length; ++$i) {
                for ($j = 0; $j < $fields2Length; ++$j) {
                    $conflict = $this->findConflict(
                        $context,
                        $parentFieldsAreMutuallyExclusive,
                        $responseName,
                        $fields1[$i],
                        $fields2[$j]
                    );
                    if ($conflict !== null) {
                        $conflicts[] = $conflict;
                    }
                }
            }
        }
    }

    /**
     * Collect all conflicts found between a set of fields and a fragment reference
     * including via spreading in any nested fragments.
     *
     * @param array<string, true> $comparedFragments
     *
     * @phpstan-param array<int, Conflict> $conflicts
     * @phpstan-param FieldMap $fieldMap
     *
     * @throws \Exception
     */
    protected function collectConflictsBetweenFieldsAndFragment(
        QueryValidationContext $context,
        array &$conflicts,
        array &$comparedFragments,
        bool $areMutuallyExclusive,
        array $fieldMap,
        string $fragmentName
    ): void {
        if (isset($comparedFragments[$fragmentName])) {
            return;
        }

        $comparedFragments[$fragmentName] = true;

        $fragment = $context->getFragment($fragmentName);
        if ($fragment === null) {
            return;
        }

        [$fieldMap2, $fragmentNames2] = $this->getReferencedFieldsAndFragmentNames(
            $context,
            $fragment
        );

        if ($fieldMap === $fieldMap2) {
            return;
        }

        // (D) First collect any conflicts between the provided collection of fields
        // and the collection of fields represented by the given fragment.
        $this->collectConflictsBetween(
            $context,
            $conflicts,
            $areMutuallyExclusive,
            $fieldMap,
            $fieldMap2
        );

        // (E) Then collect any conflicts between the provided collection of fields
        // and any fragment names found in the given fragment.
        $fragmentNames2Length = count($fragmentNames2);
        for ($i = 0; $i < $fragmentNames2Length; ++$i) {
            $this->collectConflictsBetweenFieldsAndFragment(
                $context,
                $conflicts,
                $comparedFragments,
                $areMutuallyExclusive,
                $fieldMap,
                $fragmentNames2[$i]
            );
        }
    }

    /**
     * Given a reference to a fragment, return the represented collection of fields
     * as well as a list of nested fragment names referenced via fragment spreads.
     *
     * @phpstan-return array{FieldMap, array<int, string>}
     *
     * @throws \Exception
     */
    protected function getReferencedFieldsAndFragmentNames(
        QueryValidationContext $context,
        FragmentDefinitionNode $fragment
    ): array {
        // Short-circuit building a type from the AST if possible.
        if (isset($this->cachedFieldsAndFragmentNames[$fragment->selectionSet])) {
            return $this->cachedFieldsAndFragmentNames[$fragment->selectionSet];
        }

        $fragmentType = AST::typeFromAST([$context->getSchema(), 'getType'], $fragment->typeCondition);

        return $this->getFieldsAndFragmentNames(
            $context,
            $fragmentType,
            $fragment->selectionSet
        );
    }

    /**
     * Collect all conflicts found between two fragments, including via spreading in
     * any nested fragments.
     *
     * @phpstan-param array<int, Conflict> $conflicts
     *
     * @throws \Exception
     */
    protected function collectConflictsBetweenFragments(
        QueryValidationContext $context,
        array &$conflicts,
        bool $areMutuallyExclusive,
        string $fragmentName1,
        string $fragmentName2
    ): void {
        // No need to compare a fragment to itself.
        if ($fragmentName1 === $fragmentName2) {
            return;
        }

        // Memoize so two fragments are not compared for conflicts more than once.
        if (
            $this->comparedFragmentPairs->has(
                $fragmentName1,
                $fragmentName2,
                $areMutuallyExclusive
            )
        ) {
            return;
        }

        $this->comparedFragmentPairs->add(
            $fragmentName1,
            $fragmentName2,
            $areMutuallyExclusive
        );

        $fragment1 = $context->getFragment($fragmentName1);
        $fragment2 = $context->getFragment($fragmentName2);
        if ($fragment1 === null || $fragment2 === null) {
            return;
        }

        [$fieldMap1, $fragmentNames1] = $this->getReferencedFieldsAndFragmentNames(
            $context,
            $fragment1
        );
        [$fieldMap2, $fragmentNames2] = $this->getReferencedFieldsAndFragmentNames(
            $context,
            $fragment2
        );

        // (F) First, collect all conflicts between these two collections of fields
        // (not including any nested fragments).
        $this->collectConflictsBetween(
            $context,
            $conflicts,
            $areMutuallyExclusive,
            $fieldMap1,
            $fieldMap2
        );

        // (G) Then collect conflicts between the first fragment and any nested
        // fragments spread in the second fragment.
        $fragmentNames2Length = count($fragmentNames2);
        for ($j = 0; $j < $fragmentNames2Length; ++$j) {
            $this->collectConflictsBetweenFragments(
                $context,
                $conflicts,
                $areMutuallyExclusive,
                $fragmentName1,
                $fragmentNames2[$j]
            );
        }

        // (G) Then collect conflicts between the second fragment and any nested
        // fragments spread in the first fragment.
        $fragmentNames1Length = count($fragmentNames1);
        for ($i = 0; $i < $fragmentNames1Length; ++$i) {
            $this->collectConflictsBetweenFragments(
                $context,
                $conflicts,
                $areMutuallyExclusive,
                $fragmentNames1[$i],
                $fragmentName2
            );
        }
    }

    /**
     * Merge Conflicts between two sub-fields into a single Conflict.
     *
     * @phpstan-param array<int, Conflict> $conflicts
     *
     * @phpstan-return Conflict|null
     */
    protected function subfieldConflicts(
        array $conflicts,
        string $responseName,
        FieldNode $ast1,
        FieldNode $ast2
    ): ?array {
        if ($conflicts === []) {
            return null;
        }

        $reasons = [];
        foreach ($conflicts as $conflict) {
            $reasons[] = $conflict[0];
        }

        $fields1 = [$ast1];
        foreach ($conflicts as $conflict) {
            foreach ($conflict[1] as $field) {
                $fields1[] = $field;
            }
        }

        $fields2 = [$ast2];
        foreach ($conflicts as $conflict) {
            foreach ($conflict[2] as $field) {
                $fields2[] = $field;
            }
        }

        return [
            [
                $responseName,
                $reasons,
            ],
            $fields1,
            $fields2,
        ];
    }

    /**
     * @param string|array $reasonOrReasons
     *
     * @phpstan-param ReasonOrReasons $reasonOrReasons
     */
    public static function fieldsConflictMessage(string $responseName, $reasonOrReasons): string
    {
        $reasonMessage = static::reasonMessage($reasonOrReasons);

        return "Fields \"{$responseName}\" conflict because {$reasonMessage}. Use different aliases on the fields to fetch both if this was intentional.";
    }

    /**
     * @param string|array $reasonOrReasons
     *
     * @phpstan-param ReasonOrReasons $reasonOrReasons
     */
    public static function reasonMessage($reasonOrReasons): string
    {
        if (is_array($reasonOrReasons)) {
            $reasons = array_map(
                static function (array $reason): string {
                    [$responseName, $subReason] = $reason;
                    $reasonMessage = static::reasonMessage($subReason);

                    return "subfields \"{$responseName}\" conflict because {$reasonMessage}";
                },
                $reasonOrReasons
            );

            return implode(' and ', $reasons);
        }

        return $reasonOrReasons;
    }
}
Name	Size	Permission
CustomValidationRule.php	982 bytes	0644
DisableIntrospection.php	1428 bytes	0644
ExecutableDefinitions.php	2093 bytes	0644
FieldsOnCorrectType.php	5239 bytes	0644
FragmentsOnCompositeTypes.php	2212 bytes	0644
KnownArgumentNames.php	2471 bytes	0644
KnownArgumentNamesOnDirectives.php	3669 bytes	0644
KnownDirectives.php	7939 bytes	0644
KnownFragmentNames.php	1023 bytes	0644
KnownTypeNames.php	3455 bytes	0644
LoneAnonymousOperation.php	1591 bytes	0644
LoneSchemaDefinition.php	1793 bytes	0644
NoFragmentCycles.php	3359 bytes	0644
NoUndefinedVariables.php	2351 bytes	0644
NoUnusedFragments.php	2229 bytes	0644
NoUnusedVariables.php	2211 bytes	0644
OverlappingFieldsCanBeMerged.php	31858 bytes	0644
PossibleFragmentSpreads.php	6390 bytes	0644
PossibleTypeExtensions.php	6340 bytes	0644
ProvidedRequiredArguments.php	2024 bytes	0644
ProvidedRequiredArgumentsOnDirectives.php	4287 bytes	0644
QueryComplexity.php	9211 bytes	0644
QueryDepth.php	4144 bytes	0644
QuerySecurityRule.php	6556 bytes	0644
ScalarLeafs.php	1687 bytes	0644
SingleFieldSubscription.php	1506 bytes	0644
UniqueArgumentDefinitionNames.php	2857 bytes	0644
UniqueArgumentNames.php	2003 bytes	0644
UniqueDirectiveNames.php	1971 bytes	0644
UniqueDirectivesPerLocation.php	3165 bytes	0644
UniqueEnumValueNames.php	2450 bytes	0644
UniqueFieldDefinitionNames.php	3831 bytes	0644
UniqueFragmentNames.php	1541 bytes	0644
UniqueInputFieldNames.php	2446 bytes	0644
UniqueOperationNames.php	1692 bytes	0644
UniqueOperationTypes.php	2420 bytes	0644
UniqueTypeNames.php	2172 bytes	0644
UniqueVariableNames.php	1473 bytes	0644
ValidationRule.php	870 bytes	0644
ValuesOfCorrectType.php	7329 bytes	0644
VariablesAreInputTypes.php	1361 bytes	0644
VariablesInAllowedPosition.php	4705 bytes	0644
File Content: OverlappingFieldsCanBeMerged.php

File Content: `OverlappingFieldsCanBeMerged.php`
