[9.x] Fix decimal cast, again (#45602)

* Fix decimal cast, again

* code style

* Wrap exception in first party exception

Eloquent/Concerns/HasAttributes.php

@@ -3,6 +3,9 @@
 namespace Illuminate\Database\Eloquent\Concerns;
 
 use BackedEnum;
+use Brick\Math\BigDecimal;
+use Brick\Math\Exception\MathException as BrickMathException;
+use Brick\Math\RoundingMode;
 use Carbon\CarbonImmutable;
 use Carbon\CarbonInterface;
 use DateTimeImmutable;
@@ -23,6 +26,7 @@
 use Illuminate\Support\Arr;
 use Illuminate\Support\Carbon;
 use Illuminate\Support\Collection as BaseCollection;
+use Illuminate\Support\Exceptions\MathException;
 use Illuminate\Support\Facades\Crypt;
 use Illuminate\Support\Facades\Date;
 use Illuminate\Support\Str;
@@ -31,8 +35,6 @@
 use ReflectionClass;
 use ReflectionMethod;
 use ReflectionNamedType;
-use RuntimeException;
-use TypeError;
 
 trait HasAttributes
 {
@@ -1322,21 +1324,11 @@ public function fromFloat($value)
      */
     protected function asDecimal($value, $decimals)
     {
-        if (extension_loaded('bcmath')) {
-            return bcadd($value, 0, $decimals);
-        }
-
-        if (! is_numeric($value)) {
-            throw new TypeError('$value must be numeric.');
-        }
-
-        if (is_string($value) && Str::contains($value, 'e', true)) {
-            throw new RuntimeException('The "decimal" model cast is unable to handle string based floats with exponents.');
+        try {
+            return (string) BigDecimal::of($value)->toScale($decimals, RoundingMode::HALF_UP);
+        } catch (BrickMathException $e) {
+            throw new MathException('Unable to cast value to a decimal.', previous: $e);
         }
-
-        [$int, $fraction] = explode('.', $value) + [1 => ''];
-
-        return Str::of($int)->padLeft('1', '0').'.'.Str::of($fraction)->limit($decimals, '')->padRight($decimals, '0');
     }
 
     /**