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Improve StrSplit returnType #3999

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ffc1a15
Improve StrSplit returnType
VincentLanglet May 18, 2025
a74b5f9
Add tests
VincentLanglet Jun 12, 2025
f30c52a
Rework extension
VincentLanglet Jun 12, 2025
14649b5
Fix
VincentLanglet Jun 13, 2025
e471895
Improve
VincentLanglet Jun 13, 2025
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5 changes: 0 additions & 5 deletions build/baseline-8.0.neon
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Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,6 @@ parameters:
count: 1
path: ../src/Type/Php/StrSplitFunctionReturnTypeExtension.php

-
message: "#^Strict comparison using \\=\\=\\= between list<string> and false will always evaluate to false\\.$#"
count: 1
path: ../src/Type/Php/StrSplitFunctionReturnTypeExtension.php

-
message: "#^Call to function is_bool\\(\\) with string will always evaluate to false\\.$#"
count: 1
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2 changes: 1 addition & 1 deletion src/Php/PhpVersion.php
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Expand Up @@ -236,7 +236,7 @@ public function deprecatesDynamicProperties(): bool
return $this->versionId >= 80200;
}

public function strSplitReturnsEmptyArray(): bool
public function strSplitReturnsEmptyArrayOnEmptyString(): bool
{
return $this->versionId >= 80200;
}
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95 changes: 61 additions & 34 deletions src/Type/Php/StrSplitFunctionReturnTypeExtension.php
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Expand Up @@ -9,14 +9,17 @@
use PHPStan\ShouldNotHappenException;
use PHPStan\TrinaryLogic;
use PHPStan\Type\Accessory\AccessoryArrayListType;
use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
use PHPStan\Type\Accessory\NonEmptyArrayType;
use PHPStan\Type\ArrayType;
use PHPStan\Type\Constant\ConstantArrayType;
use PHPStan\Type\Constant\ConstantBooleanType;
use PHPStan\Type\Constant\ConstantIntegerType;
use PHPStan\Type\Constant\ConstantStringType;
use PHPStan\Type\DynamicFunctionReturnTypeExtension;
use PHPStan\Type\IntegerRangeType;
use PHPStan\Type\IntegerType;
use PHPStan\Type\NeverType;
use PHPStan\Type\StringType;
use PHPStan\Type\Type;
use PHPStan\Type\TypeCombinator;
Expand Down Expand Up @@ -51,14 +54,15 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,

if (count($functionCall->getArgs()) >= 2) {
$splitLengthType = $scope->getType($functionCall->getArgs()[1]->value);
if ($splitLengthType instanceof ConstantIntegerType) {
$splitLength = $splitLengthType->getValue();
if ($splitLength < 1) {
return new ConstantBooleanType(false);
}
}
} else {
$splitLength = 1;
$splitLengthType = new ConstantIntegerType(1);
}

if ($splitLengthType instanceof ConstantIntegerType) {
$splitLength = $splitLengthType->getValue();
if ($splitLength < 1) {
return $this->phpVersion->throwsValueErrorForInternalFunctions() ? new NeverType() : new ConstantBooleanType(false);
}
}

$encoding = null;
Expand All @@ -67,47 +71,70 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
$strings = $scope->getType($functionCall->getArgs()[2]->value)->getConstantStrings();
$values = array_unique(array_map(static fn (ConstantStringType $encoding): string => $encoding->getValue(), $strings));

if (count($values) !== 1) {
return null;
}

$encoding = $values[0];
if (!$this->isSupportedEncoding($encoding)) {
return new ConstantBooleanType(false);
if (count($values) === 1) {
$encoding = $values[0];
if (!$this->isSupportedEncoding($encoding)) {
return $this->phpVersion->throwsValueErrorForInternalFunctions() ? new NeverType() : new ConstantBooleanType(false);
}
}
} else {
$encoding = mb_internal_encoding();
}
}

if (!isset($splitLength)) {
return null;
}

$stringType = $scope->getType($functionCall->getArgs()[0]->value);

$constantStrings = $stringType->getConstantStrings();
if (count($constantStrings) > 0) {
$results = [];
foreach ($constantStrings as $constantString) {
$items = $encoding === null
? str_split($constantString->getValue(), $splitLength)
: @mb_str_split($constantString->getValue(), $splitLength, $encoding);
if ($items === false) {
throw new ShouldNotHappenException();
if (
isset($splitLength)
&& ($functionReflection->getName() === 'str_split' || $encoding !== null)
) {
$constantStrings = $stringType->getConstantStrings();
if (count($constantStrings) > 0) {
$results = [];
foreach ($constantStrings as $constantString) {
$value = $constantString->getValue();

if ($encoding === null && $value === '') {
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This logic exists to avoid the same issue than phpstan/phpstan#13129

// Simulate the str_split call with the analysed PHP Version instead of the runtime one.
$items = $this->phpVersion->strSplitReturnsEmptyArrayOnEmptyString() ? [] : [''];
} else {
$items = $encoding === null
? str_split($value, $splitLength)
: @mb_str_split($value, $splitLength, $encoding);
}

$results[] = self::createConstantArrayFrom($items, $scope);
}

$results[] = self::createConstantArrayFrom($items, $scope);
return TypeCombinator::union(...$results);
}
}

return TypeCombinator::union(...$results);
$isInputNonEmptyString = $stringType->isNonEmptyString()->yes();

if ($isInputNonEmptyString || $this->phpVersion->strSplitReturnsEmptyArrayOnEmptyString()) {
$returnValueType = TypeCombinator::intersect(new StringType(), new AccessoryNonEmptyStringType());
} else {
$returnValueType = new StringType();
}

$returnType = AccessoryArrayListType::intersectWith(new ArrayType(new IntegerType(), new StringType()));
$returnType = AccessoryArrayListType::intersectWith(TypeCombinator::intersect(new ArrayType(new IntegerType(), $returnValueType)));
if (
// Non-empty-string will return an array with at least an element
$isInputNonEmptyString
// str_split('', 1) returns [''] on old PHP version and [] on new ones
|| ($functionReflection->getName() === 'str_split' && !$this->phpVersion->strSplitReturnsEmptyArrayOnEmptyString())
) {
$returnType = TypeCombinator::intersect($returnType, new NonEmptyArrayType());
}
if (
// Length parameter accepts int<1, max> or throws a ValueError/return false based on PHP Version.
!$this->phpVersion->throwsValueErrorForInternalFunctions()
&& !IntegerRangeType::fromInterval(1, null)->isSuperTypeOf($splitLengthType)->yes()
) {
$returnType = TypeCombinator::union($returnType, new ConstantBooleanType(false));
}

return $encoding === null && !$this->phpVersion->strSplitReturnsEmptyArray()
? TypeCombinator::intersect($returnType, new NonEmptyArrayType())
: $returnType;
return $returnType;
}

/**
Expand Down
4 changes: 3 additions & 1 deletion tests/PHPStan/Analyser/NodeScopeResolverTest.php
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Expand Up @@ -56,7 +56,9 @@ private static function findTestFiles(): iterable
} else {
yield __DIR__ . '/data/str-split-php74.php';
}
if (PHP_VERSION_ID >= 80000) {
if (PHP_VERSION_ID >= 80200) {
yield __DIR__ . '/data/mb-str-split-php82.php';
} elseif (PHP_VERSION_ID >= 80000) {
yield __DIR__ . '/data/mb-str-split-php80.php';
} elseif (PHP_VERSION_ID >= 74000) {
yield __DIR__ . '/data/mb-str-split-php74.php';
Expand Down
57 changes: 39 additions & 18 deletions tests/PHPStan/Analyser/data/mb-str-split-php80.php
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Expand Up @@ -26,69 +26,90 @@ public function legacyTest(): void
assertType('array{\'abcdef\'}', $mbStrSplitConstantStringWithGreaterSplitLengthThanStringLength);

$mbStrSplitConstantStringWithFailureSplitLength = mb_str_split('abcdef', 0);
assertType('false', $mbStrSplitConstantStringWithFailureSplitLength);
assertType('*NEVER*', $mbStrSplitConstantStringWithFailureSplitLength);

$mbStrSplitConstantStringWithInvalidSplitLengthType = mb_str_split('abcdef', []);
assertType('list<string>', $mbStrSplitConstantStringWithInvalidSplitLengthType);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithInvalidSplitLengthType);

$mbStrSplitConstantStringWithVariableStringAndConstantSplitLength = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', 1);
assertType("array{'a', 'b', 'c', 'd', 'e', 'f'}|array{'g', 'h', 'i', 'j', 'k', 'l'}", $mbStrSplitConstantStringWithVariableStringAndConstantSplitLength);

$mbStrSplitConstantStringWithVariableStringAndVariableSplitLength = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', doFoo() ? 1 : 2);
assertType('list<string>', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLength);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLength);

$mbStrSplitConstantStringWithOneSplitLengthAndValidEncoding = mb_str_split('abcdef', 1, 'UTF-8');
assertType("array{'a', 'b', 'c', 'd', 'e', 'f'}", $mbStrSplitConstantStringWithOneSplitLengthAndValidEncoding);

$mbStrSplitConstantStringWithOneSplitLengthAndInvalidEncoding = mb_str_split('abcdef', 1, 'FAKE');
assertType('false', $mbStrSplitConstantStringWithOneSplitLengthAndInvalidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithOneSplitLengthAndInvalidEncoding);

$mbStrSplitConstantStringWithOneSplitLengthAndVariableEncoding = mb_str_split('abcdef', 1, doFoo());
assertType('list<string>', $mbStrSplitConstantStringWithOneSplitLengthAndVariableEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithOneSplitLengthAndVariableEncoding);

$mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndValidEncoding = mb_str_split('abcdef', 999, 'UTF-8');
assertType("array{'abcdef'}", $mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndValidEncoding);

$mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndInvalidEncoding = mb_str_split('abcdef', 999, 'FAKE');
assertType('false', $mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndInvalidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndInvalidEncoding);

$mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndVariableEncoding = mb_str_split('abcdef', 999, doFoo());
assertType('list<string>', $mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndVariableEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithGreaterSplitLengthThanStringLengthAndVariableEncoding);

$mbStrSplitConstantStringWithFailureSplitLengthAndValidEncoding = mb_str_split('abcdef', 0, 'UTF-8');
assertType('false', $mbStrSplitConstantStringWithFailureSplitLengthAndValidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithFailureSplitLengthAndValidEncoding);

$mbStrSplitConstantStringWithFailureSplitLengthAndInvalidEncoding = mb_str_split('abcdef', 0, 'FAKE');
assertType('false', $mbStrSplitConstantStringWithFailureSplitLengthAndInvalidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithFailureSplitLengthAndInvalidEncoding);

$mbStrSplitConstantStringWithFailureSplitLengthAndVariableEncoding = mb_str_split('abcdef', 0, doFoo());
assertType('false', $mbStrSplitConstantStringWithFailureSplitLengthAndVariableEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithFailureSplitLengthAndVariableEncoding);

$mbStrSplitConstantStringWithInvalidSplitLengthTypeAndValidEncoding = mb_str_split('abcdef', [], 'UTF-8');
assertType('list<string>', $mbStrSplitConstantStringWithInvalidSplitLengthTypeAndValidEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithInvalidSplitLengthTypeAndValidEncoding);

$mbStrSplitConstantStringWithInvalidSplitLengthTypeAndInvalidEncoding = mb_str_split('abcdef', [], 'FAKE');
assertType('false', $mbStrSplitConstantStringWithInvalidSplitLengthTypeAndInvalidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithInvalidSplitLengthTypeAndInvalidEncoding);

$mbStrSplitConstantStringWithInvalidSplitLengthTypeAndVariableEncoding = mb_str_split('abcdef', [], doFoo());
assertType('list<string>', $mbStrSplitConstantStringWithInvalidSplitLengthTypeAndVariableEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithInvalidSplitLengthTypeAndVariableEncoding);

$mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndValidEncoding = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', 1, 'UTF-8');
assertType("array{'a', 'b', 'c', 'd', 'e', 'f'}|array{'g', 'h', 'i', 'j', 'k', 'l'}", $mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndValidEncoding);

$mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndInvalidEncoding = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', 1, 'FAKE');
assertType('false', $mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndInvalidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndInvalidEncoding);

$mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndVariableEncoding = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', 1, doFoo());
assertType('list<string>', $mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndVariableEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithVariableStringAndConstantSplitLengthAndVariableEncoding);

$mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndValidEncoding = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', doFoo() ? 1 : 2, 'UTF-8');
assertType('list<string>', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndValidEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndValidEncoding);

$mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndInvalidEncoding = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', doFoo() ? 1 : 2, 'FAKE');
assertType('false', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndInvalidEncoding);
assertType('*NEVER*', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndInvalidEncoding);

$mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndVariableEncoding = mb_str_split(doFoo() ? 'abcdef' : 'ghijkl', doFoo() ? 1 : 2, doFoo());
assertType('list<string>', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndVariableEncoding);
assertType('non-empty-list<non-empty-string>', $mbStrSplitConstantStringWithVariableStringAndVariableSplitLengthAndVariableEncoding);
}

/**
* @param non-empty-string $nonEmptyString
* @param non-falsy-string $nonFalsyString
*/
function doFoo(
string $string,
string $nonEmptyString,
string $nonFalsyString,
string $lowercaseString,
string $uppercaseString,
int $integer,
):void {
assertType('list<string>', mb_str_split($string));
assertType('non-empty-list<non-empty-string>', mb_str_split($nonEmptyString));
assertType('non-empty-list<non-empty-string>', mb_str_split($nonFalsyString));

assertType('list<string>', mb_str_split($string, $integer));
assertType('non-empty-list<non-empty-string>', mb_str_split($nonEmptyString, $integer));
assertType('non-empty-list<non-empty-string>', mb_str_split($nonFalsyString, $integer));
}
}
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