Dependent variables in foreach when iterating over constant array

Author: ondrejmirtes

src/Analyser/MutatingScope.php

@@ -3464,6 +3464,36 @@ public function filterBySpecifiedTypes(SpecifiedTypes $specifiedTypes): self
 return $scope;
 }
 
+/**
+ * @param string $exprString
+ * @param ConditionalExpressionHolder[] $conditionalExpressionHolders
+ * @return self
+ */
+public function addConditionalExpressions(string $exprString, array $conditionalExpressionHolders): self
+{
+$conditionalExpressions = $this->conditionalExpressions;
+$conditionalExpressions[$exprString] = $conditionalExpressionHolders;
+return $this->scopeFactory->create(
+$this->context,
+$this->isDeclareStrictTypes(),
+$this->constantTypes,
+$this->getFunction(),
+$this->getNamespace(),
+$this->variableTypes,
+$this->moreSpecificTypes,
+$this->typeGuards,
+$conditionalExpressions,
+$this->inClosureBindScopeClass,
+$this->anonymousFunctionReflection,
+$this->inFirstLevelStatement,
+$this->currentlyAssignedExpressions,
+$this->nativeExpressionTypes,
+$this->inFunctionCallsStack,
+$this->afterExtractCall,
+$this->parentScope
+);
+}
+
 public function exitFirstLevelStatements(): self
 {
 return $this->scopeFactory->create(

src/Analyser/NodeScopeResolver.php

@@ -2753,6 +2753,7 @@ private function processVarAnnotation(MutatingScope $scope, string $variableName
 private function enterForeach(MutatingScope $scope, Foreach_ $stmt): MutatingScope
 {
 $comment = CommentHelper::getDocComment($stmt);
+$iterateeType = $scope->getType($stmt->expr);
 if ($stmt->valueVar instanceof Variable && is_string($stmt->valueVar->name)) {
 $scope = $scope->enterForeach(
 $stmt->expr,
@@ -2778,6 +2779,26 @@ private function enterForeach(MutatingScope $scope, Foreach_ $stmt): MutatingSco
 }
 }
 
+if (
+$comment === null
+&& $iterateeType instanceof ConstantArrayType
+&& $stmt->valueVar instanceof Variable && is_string($stmt->valueVar->name)
+&& $stmt->keyVar instanceof Variable && is_string($stmt->keyVar->name)
+) {
+$conditionalHolders = [];
+foreach ($iterateeType->getKeyTypes() as $i => $keyType) {
+$valueType = $iterateeType->getValueTypes()[$i];
+$conditionalHolders[] = new ConditionalExpressionHolder([
+'$' . $stmt->keyVar->name => $keyType,
+], new VariableTypeHolder($valueType, TrinaryLogic::createYes()));
+}
+
+$scope = $scope->addConditionalExpressions(
+'$' . $stmt->valueVar->name,
+$conditionalHolders
+);
+}
+
 if ($stmt->valueVar instanceof List_ || $stmt->valueVar instanceof Array_) {
 $exprType = $scope->getType($stmt->expr);
 $itemType = $exprType->getIterableValueType();

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -10546,6 +10546,11 @@ public function dataConditionalTypeWithNonEmptyArray(): array
 return $this->gatherAssertTypes(__DIR__ . '/data/conditional-non-empty-array.php');
 }
 
+public function dataForeachDependentKeyValue(): array
+{
+return $this->gatherAssertTypes(__DIR__ . '/data/foreach-dependent-key-value.php');
+}
+
 /**
  * @param string $file
  * @return array<string, mixed[]>
@@ -10741,6 +10746,7 @@ private function gatherAssertTypes(string $file): array
  * @dataProvider dataDependentVariableCertainty
  * @dataProvider dataBug1865
  * @dataProvider dataConditionalTypeWithNonEmptyArray
+ * @dataProvider dataForeachDependentKeyValue
  * @param string $assertType
  * @param string $file
  * @param mixed ...$args

tests/PHPStan/Analyser/data/foreach-dependent-key-value.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace ForeachDependentKeyValue;
+
+use function PHPStan\Analyser\assertType;
+
+class Foo
+{
+
+/**
+ * @param array{foo: int, bar: string} $a
+ */
+public function doFoo(array $a): void
+{
+foreach ($a as $key => $val) {
+assertType('int|string', $val);
+if ($key === 'foo') {
+assertType('int', $val);
+} else {
+assertType('string', $val);
+}
+
+if ($key === 'bar') {
+assertType('string', $val);
+} else {
+assertType('int', $val);
+}
+}
+}
+
+}