Replace FAUX function call workarounds

src/Analyser/MutatingScope.php

@@ -3228,6 +3228,11 @@ public function filterByTruthyValue(Expr $expr): self
 		}
 
 		$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition($this, $expr, TypeSpecifierContext::createTruthy());
+		if ($specifiedTypes->isEquality() && $this->getType($expr)->isBoolean()->yes()) {
+			$specifiedTypes = $specifiedTypes->unionWith(
+				$this->typeSpecifier->create($expr, new ConstantBooleanType(true), TypeSpecifierContext::createTrue(), $this),
+			);
+		}
 		$scope = $this->filterBySpecifiedTypes($specifiedTypes);
 		$this->truthyScopes[$exprString] = $scope;
 
@@ -3245,6 +3250,11 @@ public function filterByFalseyValue(Expr $expr): self
 		}
 
 		$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition($this, $expr, TypeSpecifierContext::createFalsey());
+		if ($specifiedTypes->isEquality() && $this->getType($expr)->isBoolean()->yes()) {
+			$specifiedTypes = $specifiedTypes->unionWith(
+				$this->typeSpecifier->create($expr, new ConstantBooleanType(false), TypeSpecifierContext::createTrue(), $this),
+			);
+		}
 		$scope = $this->filterBySpecifiedTypes($specifiedTypes);
 		$this->falseyScopes[$exprString] = $scope;
 

src/Analyser/NodeScopeResolver.php

@@ -143,6 +143,7 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\ClosureType;
+use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\Constant\ConstantIntegerType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\FileTypeMapper;
@@ -1148,11 +1149,19 @@ public function processStmtNode(
 				$this->callNodeCallback($nodeCallback, new NoopExpressionNode($stmt->expr, $hasAssign), $scope, $storage);
 			}
 			$scope = $result->getScope();
-			$scope = $scope->filterBySpecifiedTypes($this->typeSpecifier->specifyTypesInCondition(
+			$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition(
 				$scope,
 				$stmt->expr,
 				TypeSpecifierContext::createNull(),
-			));
+			);
+			$scope = $scope->filterBySpecifiedTypes($specifiedTypes);
+			if ($specifiedTypes->isEquality()) {
+				// Statement counterpart of the equality handling in filterByTruthyValue():
+				// store the call's true result so a duplicate void assertion statement is
+				// reported as always-true. We assign directly because void calls have no
+				// return value to protect, and intersecting true with void would produce never.
+				$scope = $scope->assignExpression($stmt->expr, new ConstantBooleanType(true), new ConstantBooleanType(true));
+			}
 			$hasYield = $result->hasYield();
 			$throwPoints = $result->getThrowPoints();
 			$impurePoints = $result->getImpurePoints();

src/Analyser/SpecifiedTypes.php

@@ -13,6 +13,8 @@ final class SpecifiedTypes
 
 	private bool $overwrite = false;
 
+	private bool $equality = false;
+
 	/** @var array<string, ConditionalExpressionHolder[]> */
 	private array $newConditionalExpressionHolders = [];
 
@@ -51,19 +53,48 @@ public function setAlwaysOverwriteTypes(): self
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = true;
+		$self->equality = $this->equality;
+		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
+		$self->rootExpr = $this->rootExpr;
+
+		return $self;
+	}
+
+	/**
+	 * Marks these types as coming from an equality check, the same concept as
+	 * the "=Type" equality assertions documented at
+	 * https://phpstan.org/writing-php-code/narrowing-types#equality-assertions
+	 *
+	 * The narrowed types are only applied; they do not determine the check
+	 * outcome, so ImpossibleCheckTypeHelper will not use them to report
+	 * always-true/false for the check expression.
+	 *
+	 * @api
+	 */
+	public function setEquality(): self
+	{
+		$self = new self($this->sureTypes, $this->sureNotTypes);
+		$self->overwrite = $this->overwrite;
+		$self->equality = true;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
 		return $self;
 	}
 
+	public function isEquality(): bool
+	{
+		return $this->equality;
+	}
+
 	/**
 	 * @api
 	 */
 	public function setRootExpr(?Expr $rootExpr): self
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = $this->overwrite;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $rootExpr;
 
@@ -77,6 +108,7 @@ public function setNewConditionalExpressionHolders(array $newConditionalExpressi
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = $this->overwrite;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
@@ -128,6 +160,7 @@ public function removeExpr(string $exprString): self
 
 		$self = new self($sureTypes, $sureNotTypes);
 		$self->overwrite = $this->overwrite;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
@@ -167,6 +200,9 @@ public function intersectWith(SpecifiedTypes $other): self
 		if ($this->overwrite && $other->overwrite) {
 			$result = $result->setAlwaysOverwriteTypes();
 		}
+		if ($this->equality || $other->equality) {
+			$result->equality = true;
+		}
 
 		return $result->setRootExpr($rootExpr);
 	}
@@ -204,6 +240,9 @@ public function unionWith(SpecifiedTypes $other): self
 		if ($this->overwrite || $other->overwrite) {
 			$result = $result->setAlwaysOverwriteTypes();
 		}
+		if ($this->equality || $other->equality) {
+			$result->equality = true;
+		}
 
 		$conditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		foreach ($other->newConditionalExpressionHolders as $exprString => $holders) {
@@ -235,6 +274,7 @@ public function normalize(Scope $scope): self
 		if ($this->overwrite) {
 			$result = $result->setAlwaysOverwriteTypes();
 		}
+		$result->equality = $this->equality;
 
 		return $result->setRootExpr($this->rootExpr);
 	}

src/Analyser/TypeSpecifier.php

@@ -469,7 +469,10 @@ static function (Type $type, callable $traverse) use ($templateTypeMap, &$contai
 					$assertedType,
 					$assert->isNegated() ? TypeSpecifierContext::createFalse() : TypeSpecifierContext::createTrue(),
 					$scope,
-				)->setRootExpr($containsUnresolvedTemplate || $assert->isEquality() ? $call : null);
+				);
+				if ($containsUnresolvedTemplate || $assert->isEquality()) {
+					$newTypes = $newTypes->setEquality();
+				}
 				$types = $types !== null ? $types->unionWith($newTypes) : $newTypes;
 
 				if (!$context->null() || !$assertedType instanceof ConstantBooleanType) {

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -322,6 +322,20 @@ private function getSpecifiedType(
 			return null;
 		}
 
+		if ($specifiedTypes->isEquality()) {
+			if ($scope->hasExpressionType($node)->yes()) {
+				$nodeType = $this->treatPhpDocTypesAsCertain ? $scope->getType($node) : $scope->getNativeType($node);
+				if ($nodeType->isTrue()->yes()) {
+					return true;
+				}
+				if ($nodeType->isFalse()->yes()) {
+					return false;
+				}
+			}
+
+			return null;
+		}
+
 		$sureTypes = $specifiedTypes->getSureTypes();
 		$sureNotTypes = $specifiedTypes->getSureNotTypes();
 

src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php

@@ -3,10 +3,7 @@
 namespace PHPStan\Type\Php;
 
 use PhpParser\Node\Expr\ArrayDimFetch;
-use PhpParser\Node\Expr\BinaryOp\Identical;
-use PhpParser\Node\Expr\ConstFetch;
 use PhpParser\Node\Expr\FuncCall;
-use PhpParser\Node\Name;
 use PHPStan\Analyser\Scope;
 use PHPStan\Analyser\SpecifiedTypes;
 use PHPStan\Analyser\TypeSpecifier;
@@ -115,7 +112,7 @@ public function specifyTypes(
 					$arrayType->getIterableValueType(),
 					$context,
 					$scope,
-				))->setRootExpr(new Identical($arrayDimFetch, new ConstFetch(new Name('__PHPSTAN_FAUX_CONSTANT'))));
+				))->setEquality();
 			}
 
 			return new SpecifiedTypes();

src/Type/Php/PregMatchTypeSpecifyingExtension.php

@@ -106,7 +106,7 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 			$matchedType,
 			$context,
 			$scope,
-		)->setRootExpr($node);
+		)->setEquality();
 		if ($overwrite) {
 			$types = $types->setAlwaysOverwriteTypes();
 		}

src/Type/Php/StrContainingTypeSpecifyingExtension.php

@@ -2,12 +2,7 @@
 
 namespace PHPStan\Type\Php;
 
-use PhpParser\Node\Arg;
-use PhpParser\Node\Expr\BinaryOp\BooleanAnd;
-use PhpParser\Node\Expr\BinaryOp\NotIdentical;
 use PhpParser\Node\Expr\FuncCall;
-use PhpParser\Node\Name;
-use PhpParser\Node\Scalar\String_;
 use PHPStan\Analyser\Scope;
 use PHPStan\Analyser\SpecifiedTypes;
 use PHPStan\Analyser\TypeSpecifier;
@@ -100,15 +95,7 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 					new IntersectionType($accessories),
 					$context,
 					$scope,
-				)->setRootExpr(new BooleanAnd(
-					new NotIdentical(
-						$args[$needleArg]->value,
-						new String_(''),
-					),
-					new FuncCall(new Name('FAUX_FUNCTION'), [
-						new Arg($args[$needleArg]->value),
-					]),
-				));
+				)->setEquality();
 
 				if (in_array($lowerFunctionName, self::SUBSTRING_PROVING_FUNCTIONS, true)) {
 					$specifiedTypes = $specifiedTypes