Faster MutatingScope->mergeWith(Scope)

Author: staabm

src/Analyser/ExpressionTypeHolder.php

@@ -36,6 +36,10 @@ public function equals(self $other): bool
 	public function and(self $other): self
 	{
 		if ($this->type->equals($other->type)) {
+			if ($this->certainty->equals($other->certainty)) {
+				return $this;
+			}
+
 			$type = $this->type;
 		} else {
 			$type = TypeCombinator::union($this->type, $other->type);

src/Analyser/MutatingScope.php

@@ -4773,6 +4773,11 @@ private function mergeVariableHolders(array $ourVariableTypeHolders, array $thei
 		$intersectedVariableTypeHolders = [];
 		foreach ($ourVariableTypeHolders as $exprString => $variableTypeHolder) {
 			if (isset($theirVariableTypeHolders[$exprString])) {
+				if ($variableTypeHolder === $theirVariableTypeHolders[$exprString]) {
+					$intersectedVariableTypeHolders[$exprString] = $variableTypeHolder;
+					continue;
+				}
+
 				$intersectedVariableTypeHolders[$exprString] = $variableTypeHolder->and($theirVariableTypeHolders[$exprString]);
 			} else {
 				$intersectedVariableTypeHolders[$exprString] = ExpressionTypeHolder::createMaybe($variableTypeHolder->getExpr(), $variableTypeHolder->getType());