fix

Author: clxmstaab

src/Analyser/MutatingScope.php

@@ -1102,7 +1102,7 @@ private function resolveType(Expr $node): Type
 			}
 
 			// we limit the number of union-types for performance reasons
-			if ($leftStringType instanceof UnionType && count($leftStringType->getTypes()) < 32 && $rightStringType instanceof ConstantStringType) {
+			if ($leftStringType instanceof UnionType && count($leftStringType->getTypes()) <= 16 && $rightStringType instanceof ConstantStringType) {
 				$constantStrings = TypeUtils::getConstantStrings($leftStringType);
 				if (count($constantStrings) > 0) {
 					$strings = [];
@@ -1113,7 +1113,7 @@ private function resolveType(Expr $node): Type
 					return TypeCombinator::union(...$strings);
 				}
 			}
-			if ($rightStringType instanceof UnionType && count($rightStringType->getTypes()) < 32 && $leftStringType instanceof ConstantStringType) {
+			if ($rightStringType instanceof UnionType && count($rightStringType->getTypes()) <= 16 && $leftStringType instanceof ConstantStringType) {
 				$constantStrings = TypeUtils::getConstantStrings($rightStringType);
 				if (count($constantStrings) > 0) {
 					$strings = [];

tests/PHPStan/Analyser/data/bug-6439.php

@@ -34,30 +34,29 @@ public function unionOnRight(string $name, ?int $gesperrt = null, ?int $adaid =
 	}
 
 	public function testLimit() {
-		$string = 'i';
+		$string = '0';
 
 		if (rand(0,1)) {
-			$string .= ' a';
+			$string .= 'a';
 		}
 		if (rand(0,1)) {
-			$string .= ' b';
+			$string .= 'b';
 		}
 		if (rand(0,1)) {
-			$string .= ' c';
+			$string .= 'c';
 		}
 		if (rand(0,1)) {
-			$string .= ' d';
+			$string .= 'd';
 		}
 		if (rand(0,1)) {
-			$string .= ' e';
-		}
-		assertType("'i'|'i a'|'i a b'|'i a b c'|'i a b c d'|'i a b c d e'|'i a b c e'|'i a b d'|'i a b d e'|'i a b e'|'i a c'|'i a c d'|'i a c d e'|'i a c e'|'i a d'|'i a d e'|'i a e'|'i b'|'i b c'|'i b c d'|'i b c d e'|'i b c e'|'i b d'|'i b d e'|'i b e'|'i c'|'i c d'|'i c d e'|'i c e'|'i d'|'i d e'|'i e'", $string);
+			$string .= 'e';
 
-		if (rand(0,1)) {
-			$string .= ' f';
-		}
-
-		assertType("literal-string&non-empty-string", $string);
+			// union should contain 32 elements
+			assertType("'0'|'0a'|'0ab'|'0abc'|'0abcd'|'0abcde'|'0abce'|'0abd'|'0abde'|'0abe'|'0ac'|'0acd'|'0acde'|'0ace'|'0ad'|'0ade'|'0ae'|'0b'|'0bc'|'0bcd'|'0bcde'|'0bce'|'0bd'|'0bde'|'0be'|'0c'|'0cd'|'0cde'|'0ce'|'0d'|'0de'|'0e'", $string);
 
+			// adding more elements should fallback to the more general form
+			$string .= 'too-long';
+			assertType("literal-string&non-empty-string", $string);
+		}
 	}
 }