Let the running engine keep its word first in the pattern rule

Every message a baseline ever wrote stays: the running engine reports a
pattern both judges refuse with its own words, and the analysed engine
speaks only for one the running engine compiles and the analysed project
refuses - the crash the project meets on its own machine, invisible
here. The upgrade section stands on its own and carries the preg_split
change.

Author: yoeunes

UPGRADING.md

@@ -1,5 +1,7 @@
-Upgrading from PHPStan 1.x to 2.0
-=================================
+# The regex pipeline reads through the PHPRegex parser
+
+The change log of the pull request that replaces the vendored Hoa PCRE
+grammar; the sections below are the standing upgrade guides.
 
 ## PHP version requirements
 
@@ -68,6 +70,10 @@ their shapes; the ones that change, change toward what the engine does:
   `preg_match('/^(a|b|c)$/', $x)`).
 
 If an inferred `$matches` type narrows past what your code expects, the
+- `preg_split()` with a limit or a flags value no constant names keeps
+  the generic list type (`non-empty-list<string>|false`, offset pairs
+  where the flags may ask for them) instead of collapsing to a bare
+  `false`.
 baseline is the place to say so — each change above is verifiable against
 the engine with a one-line `preg_match()`.
 

src/Rules/Regexp/RegularExpressionPatternRule.php

@@ -124,22 +124,18 @@ private function extractPatterns(FuncCall $functionCall, Scope $scope): array
 
 	private function validatePattern(string $pattern): ?string
 	{
-		// the pattern is judged for the analysed PHP and its engine — the
-		// project crashes on its own machine, whatever the runner takes —
-		// and the running engine stays a second witness: a construct the
-		// parser misjudges still reports
-		$refusal = $this->reader->refusalOfExpression($pattern);
-		if ($refusal !== null) {
-			return $refusal;
-		}
-
+		// the running engine keeps its word first: every message a
+		// baseline ever wrote against stays, and the analysed engine
+		// speaks only for a pattern the running one compiles and the
+		// analysed project's engine refuses — the crash the project
+		// meets on its own machine, invisible here
 		try {
 			Strings::match('', $pattern);
 		} catch (RegexpException $e) {
 			return $e->getMessage();
 		}
 
-		return null;
+		return $this->reader->refusalOfExpression($pattern);
 	}
 
 }

tests/PHPStan/Rules/Regexp/RegularExpressionPatternRuleTest.php

@@ -26,119 +26,127 @@ protected function getRule(): Rule
 
 	public function testValidRegexPattern(): void
 	{
+		$messagePart = 'alphanumeric or backslash';
+		if (PHP_VERSION_ID >= 80200) {
+			$messagePart = 'alphanumeric, backslash, or NUL';
+		}
+		if (PHP_VERSION_ID >= 80400) {
+			$messagePart = 'alphanumeric, backslash, or NUL byte';
+		}
+
 		$this->analyse(
 			[__DIR__ . '/data/valid-regex-pattern.php'],
 			[
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					6,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					7,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					11,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					12,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					16,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					17,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					21,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					22,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					26,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					27,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					29,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					29,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					32,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					33,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					35,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					35,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					38,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					39,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					41,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					41,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nonok#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok', $messagePart),
 					43,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 1',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 1 in pattern: ~(~',
 					43,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nok(?:.*nok(?:.*)#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok(?:.*)', $messagePart),
 					57,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nok(?:.*nok(?:.*)#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok(?:.*)', $messagePart),
 					58,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 7',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 7 in pattern: ~((?:.*)~',
 					59,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nok(?:.*)nono#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok(?:.*)nono', $messagePart),
 					61,
 				],
 				[
-					'Regex pattern is invalid: Invalid delimiter "n". Delimiters must not be alphanumeric, backslash, or NUL byte. Try #nok(?:.*)nope#.',
+					sprintf('Regex pattern is invalid: Delimiter must not be %s in pattern: nok(?:.*)nope', $messagePart),
 					62,
 				],
 				[
-					'Regex pattern is invalid: Expected ) at end of input (found eof) at offset 7',
+					'Regex pattern is invalid: Compilation failed: missing closing parenthesis at offset 7 in pattern: ~((?:.*)~',
 					63,
 				],
 			],
@@ -168,7 +176,7 @@ public static function dataArrayShapePatterns(): iterable
 			__DIR__ . '/../../Analyser/nsrt/preg_match_shapes.php',
 			[
 				[
-					"Regex pattern is invalid: Unknown regex flag(s) found: \"y\", \"z\" at offset 17",
+					"Regex pattern is invalid: Unknown modifier 'y' in pattern: /(foo)(bar)(baz)/xyz",
 					124,
 				],
 			],