fix(decimal): optimize integer to decimal conversion without string intermediate

- Changed integer to decimal conversion from php::toDecimal(php::toString(expr))
  to direct php::toDecimal(expr)
- Added test case to verify decimal integer operand does not convert through string
- Created new test file decimal-int-operand.php to test decimal multiplication
  with integer operands
- Added phpt test for decimal multiplication accepting Int and dynamically typed
  Int operands
- Fixed type conversion trait to handle INT type directly without string conversion

phpunit/code/big-numeric/decimal-int-operand.php

@@ -0,0 +1,22 @@
+<?php
+
+function multiplyDecimalByInt(int $factor): string
+{
+    $value = std::decimal('123.456');
+    $value = $value * 1000;
+    $value = $value * $factor;
+    return $value->toString();
+}
+
+function multiplyDecimalByVar($factor): string
+{
+    $value = std::decimal('123.456');
+    $value = $value * $factor;
+    return $value->toString();
+}
+
+function main(): void
+{
+    echo multiplyDecimalByInt(1000), "\n";
+    echo multiplyDecimalByVar(1000), "\n";
+}

phpunit/src/BigNumericValidationTest.php

@@ -2,6 +2,31 @@
 
 class BigNumericValidationTest extends \BaseTest
 {
+    public function testDecimalIntegerOperandDoesNotConvertThroughString(): void
+    {
+        global $translator;
+        $compiler = \TypePhp\CompilerTest::create(ROOT_PATH);
+        $translator = $compiler;
+        $testFile = __DIR__ . '/../code/big-numeric/decimal-int-operand.php';
+        $compiler->addFiles([$testFile]);
+        $compiler->prepareFile($testFile);
+        $cppFile = $compiler->convertFile($testFile);
+        $cpp = file_get_contents($cppFile);
+
+        $this->assertStringContainsString(
+            'php::Decimal::mul(value, php::toDecimal(1000L))',
+            $cpp,
+        );
+        $this->assertStringNotContainsString(
+            'php::toDecimal(php::toString(1000L))',
+            $cpp,
+        );
+        $this->assertStringContainsString(
+            'php::Decimal::mul(value, factor)',
+            $cpp,
+        );
+    }
+
     public function testDecimalPowerOperatorIsRejected(): void
     {
         $this->exec("Operator '**' is not supported for Decimal or BigFloat", 'big-numeric/decimal-pow-operator.php');

src/Parser/TypeConversionTrait.php

@@ -85,7 +85,7 @@ trait TypeConversionTrait
             return 'php::toDecimal(php::toString(' . $expr . '))';
         }
         if ($fromType === Type::INT) {
-            return 'php::toDecimal(php::toString(' . $expr . '))';
+            return 'php::toDecimal(' . $expr . ')';
         }
         if ($fromType === Type::BIGINT) {
             return 'php::toDecimal(php::BigInt::toString(' . $expr . '))';

tests/compiler/decimal/int-operand-without-string-conversion.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Decimal multiplication accepts Int and dynamically typed Int operands
+--FILE--
+<?php
+
+function multiplyDecimal($factor): string
+{
+    $value = std::decimal('123.456');
+    $value = $value * $factor;
+    return $value->toString();
+}
+
+function main(): void
+{
+    $value = std::decimal('123.456');
+    echo ($value * 1000)->toString(), "\n";
+    echo multiplyDecimal(1000), "\n";
+}
+?>
+--EXPECT--
+123456.000
+123456.000