Pre-compute count-specific conditional expressions to narrow list types when count() is stored in a variable
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Pre-compute count-specific conditional expressions to narrow list typ…
…es when `count()` is stored in a variable
- When `$count = count($list)` is assigned, pre-compute conditional
expressions for count values 1-8 so that `$count === N` narrows
`$list` to the exact array shape (e.g. `array{T, T, T}` for N=3)
- Previously, only inline `count($list) === 3` narrowed correctly;
storing the count in a variable only gave `non-empty-list<T>`
- The fix extends AssignHandler to call specifyTypesInCondition with
synthetic `count($expr) === N` comparisons for small N values,
storing the results as ConditionalExpressionHolders
- Works for count() and sizeof() with a single argument on list and
constant array types
- Analogous cases verified: sizeof() alias, explode() results,
non-empty-list types, switch statements, PHPDoc list types
- strlen() variable narrowing is a separate pre-existing issue with
a different mechanism (no TypeSpecifyingExtension) — not addressed- Loading branch information
commit 83af88c851c7deb104a4b5df0b5c55a3f14f0459
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,102 @@ | ||
| <?php declare(strict_types = 1); | ||
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| namespace Bug14464Analogous; | ||
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| use function PHPStan\Testing\assertType; | ||
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| /** | ||
| * sizeof() alias | ||
| * @param list<int> $items | ||
| */ | ||
| function testSizeof(array $items): void { | ||
| $count = sizeof($items); | ||
| if ($count === 3) { | ||
| assertType('array{int, int, int}', $items); | ||
| } | ||
| } | ||
|
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||
| /** | ||
| * Inline count still works | ||
| * @param list<int> $items | ||
| */ | ||
| function testInlineCount(array $items): void { | ||
| if (count($items) === 3) { | ||
| assertType('array{int, int, int}', $items); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * explode() result | ||
| */ | ||
| function testExplode(string $input): void { | ||
| $parts = explode(',', $input); | ||
| $count = count($parts); | ||
| if ($count === 3) { | ||
| assertType('array{string, string, string}', $parts); | ||
| } elseif ($count === 1) { | ||
| assertType('array{string}', $parts); | ||
| } | ||
| } | ||
|
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||
| /** | ||
| * Variable count >= N (range comparison) | ||
| * @param list<int> $items | ||
| */ | ||
| function testGreaterOrEqual(array $items): void { | ||
| $count = count($items); | ||
| if ($count >= 3) { | ||
| assertType('non-empty-list<int>', $items); | ||
| } | ||
| } | ||
|
|
||
| /** | ||
| * Count value > 8 (beyond pre-computed limit) | ||
| * @param list<int> $items | ||
| */ | ||
| function testBeyondLimit(array $items): void { | ||
| $count = count($items); | ||
| if ($count === 10) { | ||
| assertType('non-empty-list<int>', $items); | ||
| } | ||
| } | ||
|
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||
| /** | ||
| * Count with mode argument excluded from pre-computation | ||
| * @param list<int> $items | ||
| */ | ||
| function testCountWithMode(array $items, int $mode): void { | ||
| $count = count($items, $mode); | ||
| if ($count === 3) { | ||
| assertType('non-empty-list<int>', $items); | ||
| } | ||
| } | ||
|
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| /** | ||
| * Variable count on non-empty-list | ||
| * @param non-empty-list<string> $items | ||
| */ | ||
| function testNonEmptyList(array $items): void { | ||
| $count = count($items); | ||
| if ($count === 2) { | ||
| assertType('array{string, string}', $items); | ||
| } | ||
| } | ||
|
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||
| /** | ||
| * Variable count with switch statement | ||
| * @param list<int> $items | ||
| */ | ||
| function testSwitch(array $items): void { | ||
| $count = count($items); | ||
| switch ($count) { | ||
| case 1: | ||
| assertType('array{int}', $items); | ||
| break; | ||
| case 2: | ||
| assertType('array{int, int}', $items); | ||
| break; | ||
| case 3: | ||
| assertType('array{int, int, int}', $items); | ||
| break; | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,72 @@ | ||
| <?php declare(strict_types = 1); | ||
|
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| namespace Bug14464; | ||
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| use function PHPStan\Testing\assertType; | ||
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| class HelloWorld | ||
| { | ||
| /** Variable count with == (loose comparison from the issue) */ | ||
| protected function columnOrAlias(string $columnName): void | ||
| { | ||
| $colParts = preg_split('/\s+/', $columnName, -1, \PREG_SPLIT_NO_EMPTY); | ||
| if ($colParts === false) { | ||
| throw new \RuntimeException('preg error'); | ||
| } | ||
| assertType('list<non-empty-string>', $colParts); | ||
| $numParts = count($colParts); | ||
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| if ($numParts == 3) { | ||
| assertType('array{non-empty-string, non-empty-string, non-empty-string}', $colParts); | ||
| $this->columnName($colParts[0]); | ||
| $this->columnName($colParts[1]); | ||
| $this->columnName($colParts[2]); | ||
| } elseif ($numParts == 2) { | ||
| assertType('array{non-empty-string, non-empty-string}', $colParts); | ||
| $this->columnName($colParts[0]); | ||
| $this->columnName($colParts[1]); | ||
| } elseif ($numParts == 1) { | ||
| assertType('array{non-empty-string}', $colParts); | ||
| $this->columnName($colParts[0]); | ||
| } else { | ||
| throw new \LogicException('invalid'); | ||
| } | ||
| } | ||
|
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| /** Variable count with === (strict comparison) */ | ||
| protected function strictComparison(string $input): void | ||
| { | ||
| $parts = preg_split('/,/', $input, -1, \PREG_SPLIT_NO_EMPTY); | ||
| if ($parts === false) { | ||
| throw new \RuntimeException('preg error'); | ||
| } | ||
| $count = count($parts); | ||
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| if ($count === 3) { | ||
| assertType('array{non-empty-string, non-empty-string, non-empty-string}', $parts); | ||
| } elseif ($count === 1) { | ||
| assertType('array{non-empty-string}', $parts); | ||
| } | ||
| } | ||
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| /** | ||
| * Variable count on a PHPDoc list type | ||
| * @param list<int> $items | ||
| */ | ||
| protected function phpdocList(array $items): void | ||
| { | ||
| $count = count($items); | ||
| if ($count === 3) { | ||
| assertType('array{int, int, int}', $items); | ||
| } elseif ($count === 5) { | ||
| assertType('array{int, int, int, int, int}', $items); | ||
| } else { | ||
| assertType('list<int>', $items); | ||
| } | ||
| } | ||
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| public function columnName(string $columnName): string | ||
| { | ||
| return 'abc'; | ||
| } | ||
| } |
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Could we remember the expression which a variable was assigned from, in case its a pure function call?
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Done. Here's a summary of the changes made to address staabm's review:
What changed
Instead of pre-computing conditional expressions for integer values 1-8 at assignment time (the
INTEGER_CONDITIONAL_LIMITloop), the code now remembers the original FuncCall expression that was assigned to a variable and resolves it dynamically when needed.Architecture
ExpressionTypeHolder- Added an optionalassignedFromExprfield. Since ExpressionTypeHolder lives in theexpressionTypesarray which is already threaded through all scope operations, no changes to the MutatingScope constructor or the 37scopeFactory->create()calls were needed.AssignHandler- AfterassignVariable(), if the assigned expression is aFuncCall, setsassignedFromExpron the ExpressionTypeHolder. Removed the pre-computation loop andINTEGER_CONDITIONAL_LIMITconstant.TypeSpecifier::resolveIdentical()- When one side is a Variable with a remembered FuncCall, also resolves the comparison with the original FuncCall substituted in and unions the results.MutatingScope- AddedgetVariableAssignedFromExpr()method. ModifiedspecifyExpressionType(),filterBySpecifiedTypes(),processScopeForBody(), andgeneralizeVariableTypeHolders()to preserveassignedFromExprthrough type narrowing, branch merges, and loop body processing. The remembered expression is automatically cleared on variable reassignment (sinceinvalidateExpressionremoves the old holder).Benefits over pre-computation
count($arr) === 10now correctly producesarray{int, int, int, int, int, int, int, int, int, int}(previously fell back tonon-empty-list<int>)Verification