fix

Author: staabm

Diff for: src/Type/Regex/RegexGroupParser.php

@@ -110,15 +110,17 @@ public function parseGroups(string $regex): ?RegexAstWalkResult
 			RegexGroupWalkResult::createEmpty(),
 		);
 
-		// we could handle numeric-string, in case we know the regex is delimited by ^ and $
-		if ($subjectAsGroupResult->isNonFalsy()->yes()) {
-			$astWalkResult = $astWalkResult->withSubjectBaseType(
-				TypeCombinator::intersect(new StringType(), new AccessoryNonFalsyStringType()),
-			);
-		} elseif ($subjectAsGroupResult->isNonEmpty()->yes()) {
-			$astWalkResult = $astWalkResult->withSubjectBaseType(
-				TypeCombinator::intersect(new StringType(), new AccessoryNonEmptyStringType()),
-			);
+		if (!$subjectAsGroupResult->containsEmptyStringLiteral()) {
+			// we could handle numeric-string, in case we know the regex is delimited by ^ and $
+			if ($subjectAsGroupResult->isNonFalsy()->yes()) {
+				$astWalkResult = $astWalkResult->withSubjectBaseType(
+					TypeCombinator::intersect(new StringType(), new AccessoryNonFalsyStringType()),
+				);
+			} elseif ($subjectAsGroupResult->isNonEmpty()->yes()) {
+				$astWalkResult = $astWalkResult->withSubjectBaseType(
+					TypeCombinator::intersect(new StringType(), new AccessoryNonEmptyStringType()),
+				);
+			}
 		}
 
 		return $astWalkResult;

Diff for: src/Type/Regex/RegexGroupWalkResult.php

@@ -103,6 +103,20 @@ public function getOnlyLiterals(): ?array
 		return $this->onlyLiterals;
 	}
 
+	public function containsEmptyStringLiteral(): bool
+	{
+		if ($this->onlyLiterals === null) {
+			return false;
+		}
+		foreach ($this->onlyLiterals as $onlyLiteral) {
+			if ($onlyLiteral === '') {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	public function isNonEmpty(): TrinaryLogic
 	{
 		return $this->isNonEmpty;

Diff for: tests/PHPStan/Analyser/nsrt/preg_match_shapes.php

@@ -915,31 +915,31 @@ function bugEmptySubexpression (string $string): void {
 	}
 
 	if (preg_match('~|(a)~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1?: 'a'}", $matches);
+		assertType("array{0: string, 1?: 'a'}", $matches);
 	}
 
 	if (preg_match('~(a)|~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1?: 'a'}", $matches);
+		assertType("array{0: string, 1?: 'a'}", $matches);
 	}
 
 	if (preg_match('~(a)||(b)~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1?: 'a'}|array{non-empty-string, '', 'b'}", $matches);
+		assertType("array{0: string, 1?: 'a'}|array{string, '', 'b'}", $matches);
 	}
 
 	if (preg_match('~(|(a))~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1: ''|'a', 2?: 'a'}", $matches);
+		assertType("array{0: string, 1: ''|'a', 2?: 'a'}", $matches);
 	}
 
 	if (preg_match('~((a)|)~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1: ''|'a', 2?: 'a'}", $matches);
+		assertType("array{0: string, 1: ''|'a', 2?: 'a'}", $matches);
 	}
 
 	if (preg_match('~((a)||(b))~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1: ''|'a'|'b', 2?: ''|'a', 3?: 'b'}", $matches);
+		assertType("array{0: string, 1: ''|'a'|'b', 2?: ''|'a', 3?: 'b'}", $matches);
 	}
 
 	if (preg_match('~((a)|()|(b))~', $string, $matches)) {
-		assertType("array{0: non-empty-string, 1: ''|'a'|'b', 2?: ''|'a', 3?: '', 4?: 'b'}", $matches);
+		assertType("array{0: string, 1: ''|'a'|'b', 2?: ''|'a', 3?: '', 4?: 'b'}", $matches);
 	}
 }