Fix ErrorType after ArrayDimFetch

Author: staabm

src/Type/Constant/ConstantArrayType.php

@@ -652,23 +652,33 @@ public function hasOffsetValueType(Type $offsetType): TrinaryLogic
 
 	public function getOffsetValueType(Type $offsetType): Type
 	{
+		if (count($this->keyTypes) === 0) {
+			return new ErrorType();
+		}
+
 		$offsetType = $offsetType->toArrayKey();
 		$matchingValueTypes = [];
 		$all = true;
+		$maybeAll = true;
 		foreach ($this->keyTypes as $i => $keyType) {
 			if ($keyType->isSuperTypeOf($offsetType)->no()) {
 				$all = false;
+
+				if (
+					$keyType instanceof ConstantIntegerType
+					&& !$offsetType->isString()->no()
+					&& $offsetType->isConstantScalarValue()->no()
+				) {
+					continue;
+				}
+				$maybeAll = false;
 				continue;
 			}
 
 			$matchingValueTypes[] = $this->valueTypes[$i];
 		}
 
 		if ($all) {
-			if (count($this->keyTypes) === 0) {
-				return new ErrorType();
-			}
-
 			return $this->getIterableValueType();
 		}
 
@@ -681,6 +691,10 @@ public function getOffsetValueType(Type $offsetType): Type
 			return $type;
 		}
 
+		if ($maybeAll) {
+			return $this->getIterableValueType();
+		}
+
 		return new ErrorType(); // undefined offset
 	}
 

tests/PHPStan/Rules/Variables/data/bug-10577.php

@@ -20,10 +20,22 @@ public function validate(string $value): void
 			throw new \RuntimeException();
 		}
 
+		assertType("non-empty-string", $value);
+		assertType("'Test1'|'Test2'", self::MAP[$value]);
+
 		$value = self::MAP[$value] ?? $value;
 
+		assertType("non-empty-string", $value);
 		assertType("'Test1'|'Test2'", self::MAP[$value]);
 
 		// ...
 	}
+
+	public function validateNumericString(string $value): void
+	{
+		if (!is_numeric($value)) return;
+
+		assertType("numeric-string", $value);
+		assertType("'Test1'|'Test2'", self::MAP[$value]);
+	}
 }