Rename specifyOnly to equality on SpecifiedTypes

Renames setSpecifyOnly()/shouldSpecifyOnly() to setEquality()/isEquality()
and the backing property to $equality, tying the flag to the documented
"equality assertions" concept it implements
(https://phpstan.org/writing-php-code/narrowing-types#equality-assertions).
The flag is set by AssertTag::isEquality() assertions and by the
type-specifying extensions that narrow argument types as a consequence of a
check; in all those cases the narrowed types must not determine the check
outcome in ImpossibleCheckTypeHelper.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -3265,7 +3265,7 @@ public function filterByTruthyValue(Expr $expr): self
 		}
 
 		$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition($this, $expr, TypeSpecifierContext::createTruthy());
-		if ($specifiedTypes->shouldSpecifyOnly()) {
+		if ($specifiedTypes->isEquality()) {
 			$specifiedTypes = $specifiedTypes->unionWith(
 				$this->typeSpecifier->create($expr, new ConstantBooleanType(true), TypeSpecifierContext::createTrue(), $this),
 			);
@@ -3287,7 +3287,7 @@ public function filterByFalseyValue(Expr $expr): self
 		}
 
 		$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition($this, $expr, TypeSpecifierContext::createFalsey());
-		if ($specifiedTypes->shouldSpecifyOnly()) {
+		if ($specifiedTypes->isEquality()) {
 			$specifiedTypes = $specifiedTypes->unionWith(
 				$this->typeSpecifier->create($expr, new ConstantBooleanType(false), TypeSpecifierContext::createTrue(), $this),
 			);

src/Analyser/NodeScopeResolver.php

@@ -1150,8 +1150,8 @@ public function processStmtNode(
 				TypeSpecifierContext::createNull(),
 			);
 			$scope = $scope->filterBySpecifiedTypes($specifiedTypes);
-			if ($specifiedTypes->shouldSpecifyOnly()) {
-				// Statement counterpart of the specifyOnly handling in filterByTruthyValue():
+			if ($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.

src/Analyser/SpecifiedTypes.php

@@ -13,7 +13,7 @@ final class SpecifiedTypes
 
 	private bool $overwrite = false;
 
-	private bool $specifyOnly = false;
+	private bool $equality = false;
 
 	/** @var array<string, ConditionalExpressionHolder[]> */
 	private array $newConditionalExpressionHolders = [];
@@ -53,34 +53,38 @@ public function setAlwaysOverwriteTypes(): self
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = true;
-		$self->specifyOnly = $this->specifyOnly;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
 		return $self;
 	}
 
 	/**
-	 * Marks these SpecifiedTypes as only narrowing types, not determining
-	 * the check outcome. ImpossibleCheckTypeHelper will not use sureTypes
-	 * to report always-true/false for the check expression.
+	 * 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 setSpecifyOnly(): self
+	public function setEquality(): self
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = $this->overwrite;
-		$self->specifyOnly = true;
+		$self->equality = true;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
 		return $self;
 	}
 
-	public function shouldSpecifyOnly(): bool
+	public function isEquality(): bool
 	{
-		return $this->specifyOnly;
+		return $this->equality;
 	}
 
 	/**
@@ -90,7 +94,7 @@ public function setRootExpr(?Expr $rootExpr): self
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = $this->overwrite;
-		$self->specifyOnly = $this->specifyOnly;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $rootExpr;
 
@@ -104,7 +108,7 @@ public function setNewConditionalExpressionHolders(array $newConditionalExpressi
 	{
 		$self = new self($this->sureTypes, $this->sureNotTypes);
 		$self->overwrite = $this->overwrite;
-		$self->specifyOnly = $this->specifyOnly;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
@@ -156,7 +160,7 @@ public function removeExpr(string $exprString): self
 
 		$self = new self($sureTypes, $sureNotTypes);
 		$self->overwrite = $this->overwrite;
-		$self->specifyOnly = $this->specifyOnly;
+		$self->equality = $this->equality;
 		$self->newConditionalExpressionHolders = $this->newConditionalExpressionHolders;
 		$self->rootExpr = $this->rootExpr;
 
@@ -196,8 +200,8 @@ public function intersectWith(SpecifiedTypes $other): self
 		if ($this->overwrite && $other->overwrite) {
 			$result = $result->setAlwaysOverwriteTypes();
 		}
-		if ($this->specifyOnly || $other->specifyOnly) {
-			$result->specifyOnly = true;
+		if ($this->equality || $other->equality) {
+			$result->equality = true;
 		}
 
 		return $result->setRootExpr($rootExpr);
@@ -236,8 +240,8 @@ public function unionWith(SpecifiedTypes $other): self
 		if ($this->overwrite || $other->overwrite) {
 			$result = $result->setAlwaysOverwriteTypes();
 		}
-		if ($this->specifyOnly || $other->specifyOnly) {
-			$result->specifyOnly = true;
+		if ($this->equality || $other->equality) {
+			$result->equality = true;
 		}
 
 		$conditionalExpressionHolders = $this->newConditionalExpressionHolders;
@@ -270,7 +274,7 @@ public function normalize(Scope $scope): self
 		if ($this->overwrite) {
 			$result = $result->setAlwaysOverwriteTypes();
 		}
-		$result->specifyOnly = $this->specifyOnly;
+		$result->equality = $this->equality;
 
 		return $result->setRootExpr($this->rootExpr);
 	}

src/Analyser/TypeSpecifier.php

@@ -1858,7 +1858,7 @@ static function (Type $type, callable $traverse) use ($templateTypeMap, &$contai
 					$scope,
 				);
 				if ($containsUnresolvedTemplate || $assert->isEquality()) {
-					$newTypes = $newTypes->setSpecifyOnly();
+					$newTypes = $newTypes->setEquality();
 				}
 				$types = $types !== null ? $types->unionWith($newTypes) : $newTypes;
 

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -273,7 +273,7 @@ public function findSpecifiedType(
 			return null;
 		}
 
-		if ($specifiedTypes->shouldSpecifyOnly()) {
+		if ($specifiedTypes->isEquality()) {
 			if ($scope->hasExpressionType($node)->yes()) {
 				$nodeType = $this->treatPhpDocTypesAsCertain ? $scope->getType($node) : $scope->getNativeType($node);
 				if ($nodeType->isTrue()->yes()) {

src/Type/Php/ArrayKeyExistsFunctionTypeSpecifyingExtension.php

@@ -112,7 +112,7 @@ public function specifyTypes(
 					$arrayType->getIterableValueType(),
 					$context,
 					$scope,
-				))->setSpecifyOnly();
+				))->setEquality();
 			}
 
 			return new SpecifiedTypes();

src/Type/Php/PregMatchTypeSpecifyingExtension.php

@@ -83,7 +83,7 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 			$matchedType,
 			$context,
 			$scope,
-		)->setSpecifyOnly();
+		)->setEquality();
 		if ($overwrite) {
 			$types = $types->setAlwaysOverwriteTypes();
 		}

src/Type/Php/StrContainingTypeSpecifyingExtension.php

@@ -84,7 +84,7 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 					new IntersectionType($accessories),
 					$context,
 					$scope,
-				)->setSpecifyOnly();
+				)->setEquality();
 			}
 		}