Resolve substr based on configured PHP version

Author: VincentLanglet

build/baseline-8.0.neon

@@ -29,8 +29,3 @@ parameters:
 			message: "#^Strict comparison using \\=\\=\\= between list<string> and false will always evaluate to false\\.$#"
 			count: 1
 			path: ../src/Type/Php/StrSplitFunctionReturnTypeExtension.php
-
-		-
-			message: "#^Call to function is_bool\\(\\) with string will always evaluate to false\\.$#"
-			count: 1
-			path: ../src/Type/Php/SubstrDynamicReturnTypeExtension.php

src/Type/Php/SubstrDynamicReturnTypeExtension.php

@@ -23,6 +23,7 @@
 use function in_array;
 use function is_bool;
 use function mb_substr;
+use function strlen;
 use function substr;
 
 final class SubstrDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
@@ -74,19 +75,29 @@ public function getTypeFromFunctionCall(
 				if ($length !== null) {
 					if ($functionReflection->getName() === 'mb_substr') {
 						$substr = mb_substr($constantString->getValue(), $offset->getValue(), $length->getValue());
+					} elseif ($this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+						$substr = $this->substrOrFalse($constantString->getValue(), $offset->getValue(), $length->getValue());
 					} else {
 						$substr = substr($constantString->getValue(), $offset->getValue(), $length->getValue());
 					}
 				} else {
 					if ($functionReflection->getName() === 'mb_substr') {
 						$substr = mb_substr($constantString->getValue(), $offset->getValue());
+					} elseif ($this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+						// Simulate substr call on an older PHP version if the runtime one is too new.
+						$substr = $this->substrOrFalse($constantString->getValue(), $offset->getValue());
 					} else {
 						$substr = substr($constantString->getValue(), $offset->getValue());
 					}
 				}
 
 				if (is_bool($substr)) {
-					$results[] = new ConstantBooleanType($substr);
+					if ($this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+						$results[] = new ConstantBooleanType($substr);
+					} else {
+						// Simulate substr call on a recent PHP version if the runtime one is too old.
+						$results[] = new ConstantStringType('');
+					}
 				} else {
 					$results[] = new ConstantStringType($substr);
 				}
@@ -127,4 +138,28 @@ public function getTypeFromFunctionCall(
 		return null;
 	}
 
+	private function substrOrFalse(string $string, int $offset, ?int $length = null): false|string
+	{
+		$strlen = strlen($string);
+
+		if ($offset > $strlen) {
+			return false;
+		}
+
+		if ($length !== null && $length < 0) {
+			if ($offset < 0 && -$length > $strlen) {
+				return false;
+			}
+			if ($offset >= 0 && -$length > $strlen - $offset) {
+				return false;
+			}
+		}
+
+		if ($length === null) {
+			return substr($string, $offset);
+		}
+
+		return substr($string, $offset, $length);
+	}
+
 }

tests/PHPStan/Analyser/LooseConstComparisonPhp7Test.php renamed to tests/PHPStan/Analyser/NodeScopeResolverPhp7Test.php

@@ -4,7 +4,7 @@
 
 use PHPStan\Testing\TypeInferenceTestCase;
 
-class LooseConstComparisonPhp7Test extends TypeInferenceTestCase
+class NodeScopeResolverPhp7Test extends TypeInferenceTestCase
 {
 
 	/**
@@ -15,6 +15,8 @@ public function dataFileAsserts(): iterable
 		// compares constants according to the php-version phpstan configuration,
 		// _NOT_ the current php runtime version
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/loose-const-comparison-php7.php');
+
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-13129-php7.php');
 	}
 
 	/**
@@ -33,7 +35,7 @@ public function testFileAsserts(
 	public static function getAdditionalConfigFiles(): array
 	{
 		return [
-			__DIR__ . '/looseConstComparisonPhp7.neon',
+			__DIR__ . '/nodeScopeResolverPhp7.neon',
 		];
 	}
 

tests/PHPStan/Analyser/LooseConstComparisonPhp8Test.php renamed to tests/PHPStan/Analyser/NodeScopeResolverPhp8Test.php

@@ -4,7 +4,7 @@
 
 use PHPStan\Testing\TypeInferenceTestCase;
 
-class LooseConstComparisonPhp8Test extends TypeInferenceTestCase
+class NodeScopeResolverPhp8Test extends TypeInferenceTestCase
 {
 
 	/**
@@ -15,6 +15,8 @@ public function dataFileAsserts(): iterable
 		// compares constants according to the php-version phpstan configuration,
 		// _NOT_ the current php runtime version
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/loose-const-comparison-php8.php');
+
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-13129-php8.php');
 	}
 
 	/**
@@ -33,7 +35,7 @@ public function testFileAsserts(
 	public static function getAdditionalConfigFiles(): array
 	{
 		return [
-			__DIR__ . '/looseConstComparisonPhp8.neon',
+			__DIR__ . '/nodeScopeResolverPhp8.neon',
 		];
 	}
 

tests/PHPStan/Analyser/data/bug-13129-php7.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace Bug13129PHP7;
+
+use function PHPStan\Testing\assertType;
+
+assertType("false", substr("test", 5));
+assertType("false", substr("test", -1, -5));
+assertType("false", substr("test", 1, -4));

tests/PHPStan/Analyser/data/bug-13129-php8.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace Bug13129PHP8;
+
+use function PHPStan\Testing\assertType;
+
+assertType("''", substr("test", 5));
+assertType("''", substr("test", -1, -5));
+assertType("''", substr("test", 1, -4));