Fix

Author: ondrejmirtes

src/Analyser/MutatingScope.php

@@ -157,6 +157,7 @@
 use function in_array;
 use function is_array;
 use function is_bool;
+use function is_numeric;
 use function is_string;
 use function ltrim;
 use function md5;
@@ -1768,7 +1769,7 @@ static function (Node $node, Scope $scope) use ($arrowScope, &$arrowFunctionImpu
 					if ($node instanceof Expr\PreInc) {
 						if ($varValue === '') {
 							$varValue = '1';
-						} elseif (is_string($varValue)) {
+						} elseif (is_string($varValue) && !is_numeric($varValue)) {
 							try {
 								$varValue = str_increment($varValue);
 							} catch (ValueError) {
@@ -1780,13 +1781,13 @@ static function (Node $node, Scope $scope) use ($arrowScope, &$arrowFunctionImpu
 					} else {
 						if ($varValue === '') {
 							$varValue = -1;
-						} elseif (is_string($varValue)) {
+						} elseif (is_string($varValue) && !is_numeric($varValue)) {
 							try {
 								$varValue = str_decrement($varValue);
 							} catch (ValueError) {
 								return new NeverType();
 							}
-						} elseif (!is_bool($varValue)) {
+						} elseif (is_numeric($varValue)) {
 							--$varValue;
 						}
 					}

tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php

@@ -2992,15 +2992,15 @@ public static function dataBinaryOperations(): array
 				'++$fooString',
 			],
 			[
-				'\'foo\'',
+				'\'fon\'',
 				'--$fooString',
 			],
 			[
 				'\'fop\'',
 				'$incrementedFooString',
 			],
 			[
-				'\'foo\'',
+				'\'fon\'',
 				'$decrementedFooString',
 			],
 			[

tests/PHPStan/Analyser/nsrt/pre-dec.php

@@ -19,5 +19,5 @@ function doFoo2() {
 function doFooBar() {
 	$s = 'abc';
 	--$s;
-	assertType("'abc'", $s);
+	assertType("'abb'", $s);
 }

tests/PHPStan/Analyser/nsrt/str_decrement.php

@@ -12,14 +12,14 @@
 function foo(string $s): void
 {
 	assertType('non-empty-string', str_decrement($s));
-	assertType('*ERROR*', str_decrement(''));
-	assertType('*ERROR*', str_decrement('0'));
-	assertType('*ERROR*', str_decrement('0.0'));
-	assertType('*ERROR*', str_decrement('1.0'));
-	assertType('*ERROR*', str_decrement('a'));
-	assertType('*ERROR*', str_decrement('A'));
-	assertType('*ERROR*', str_decrement('='));
-	assertType('*ERROR*', str_decrement('字'));
+	assertType('*NEVER*', str_decrement(''));
+	assertType('*NEVER*', str_decrement('0'));
+	assertType('*NEVER*', str_decrement('0.0'));
+	assertType('*NEVER*', str_decrement('1.0'));
+	assertType('*NEVER*', str_decrement('a'));
+	assertType('*NEVER*', str_decrement('A'));
+	assertType('*NEVER*', str_decrement('='));
+	assertType('*NEVER*', str_decrement('字'));
 	assertType("'0'", str_decrement('1'));
 	assertType("'8'", str_decrement('9'));
 	assertType("'9'", str_decrement('10'));

tests/PHPStan/Analyser/nsrt/str_increment.php

@@ -12,11 +12,11 @@
 function foo(string $s)
 {
 	assertType('non-falsy-string', str_increment($s));
-	assertType('*ERROR*', str_increment(''));
-	assertType('*ERROR*', str_increment('='));
-	assertType('*ERROR*', str_increment('0.0'));
-	assertType('*ERROR*', str_increment('1.0'));
-	assertType('*ERROR*', str_increment('字'));
+	assertType('*NEVER*', str_increment(''));
+	assertType('*NEVER*', str_increment('='));
+	assertType('*NEVER*', str_increment('0.0'));
+	assertType('*NEVER*', str_increment('1.0'));
+	assertType('*NEVER*', str_increment('字'));
 	assertType("'1'", str_increment('0'));
 	assertType("'2'", str_increment('1'));
 	assertType("'b'", str_increment('a'));