fix(generator): ensure all generated C values are returned as strings

- Modified genCValue method to always return string type instead of mixed
- Changed float values to be cast to string in genCValue method
- Updated boolean values to return '1'/'0' strings instead of integers
- Fixed getInternalScalarConstantValue return type to string only
- Added explicit string casting for literal string keys in Translator
- Added comprehensive tests for C value generation ensuring source code strings
- Added comments explaining integer-string array key handling in literalStrings

phpunit/src/CompilerBaseApiTest.php

@@ -216,6 +216,20 @@ class CompilerBaseApiTest extends TestCase
         $this->assertSame('ZEND_LONG_MIN', $this->invokeMethod('genCValue', PHP_INT_MIN));
     }
 
+    public function testGeneratedCValuesAreAlwaysSourceCodeStrings(): void
+    {
+        $this->assertSame((string) M_E, $this->invokeMethod('genCValue', M_E));
+        $this->assertSame('1', $this->invokeMethod('genCValue', true));
+        $this->assertSame('0', $this->invokeMethod('genCValue', false));
+
+        $code = $this->invokeMethod(
+            'parseConstFetch',
+            new \PhpParser\Node\Expr\ConstFetch(new \PhpParser\Node\Name('M_E'))
+        );
+        $this->assertIsString($code);
+        $this->assertSame((string) M_E, $code);
+    }
+
     public function testWindowsIntegerLiteralSuffixForInternalConstants(): void
     {
         $this->setPropertyValue('platform', new Windows());

src/Generator/Utils.php

@@ -25,16 +25,16 @@ trait Utils
         return $value . $this->getPlatform()->getIntegerLiteralSuffix();
     }
 
-    protected function genCValue(mixed $value): mixed
+    protected function genCValue(mixed $value): string
     {
         if (is_int($value)) {
             return $this->genIntegerLiteral($value);
         }
         if (is_float($value)) {
-            return $value;
+            return (string) $value;
         }
         if (is_bool($value)) {
-            return $value ? 1 : 0;
+            return $value ? '1' : '0';
         }
         if (is_string($value)) {
             return $this->genCharPtr($value);

src/Parser/ConstantExpressionTrait.php

@@ -147,7 +147,7 @@ trait ConstantExpressionTrait
         return $this->isInternalConstant($name) && is_scalar($this->internalConstants[$name]);
     }
 
-    protected function getInternalScalarConstantValue(string $name): string|int|float
+    protected function getInternalScalarConstantValue(string $name): string
     {
         $value = $this->internalConstants[$name];
         if (is_int($value)) {

src/Translator.php

@@ -822,7 +822,10 @@ CODE;
         if ($this->literalStrings) {
             $code .= Type::STR . ' ' . self::LITERAL_STRINGS . '[] = {' . PHP_EOL;
             foreach ($this->literalStrings as $str => $index) {
-                $code .= Type::STR . '{ZEND_STRL("' . $this->escapeString($str) . '"), true}, // [' . $index . ']' . PHP_EOL;
+                // PHP converts canonical integer-string array keys (for
+                // example "0" and "-1") to int. literalStrings only accepts
+                // strings, so restore the original key type at this boundary.
+                $code .= Type::STR . '{ZEND_STRL("' . $this->escapeString((string) $str) . '"), true}, // [' . $index . ']' . PHP_EOL;
             }
             $code .= '};' . PHP_EOL . PHP_EOL;
         } else {