Fix #106: Improve closure rendering in stack traces

CHANGELOG.md

@@ -9,6 +9,9 @@
 - Bug #166: Fix broken link to error handling guide (@vjik)
 - Chg #170: Make all parameters of `ErrorException` constructor required (@vjik)
 - New #171: Add `$traceFileMap` parameter to `HtmlRenderer` for mapping file paths in trace links (@WarLikeLaux)
+- Enh #172: Improve closure rendering in stack traces (@WarLikeLaux)
+- Bug #172: Keep items in stack traces when source is unavailable (@WarLikeLaux)
+- Bug #172: Don't render non-positive line number in stack trace frame (@WarLikeLaux)
 
 ## 4.3.2 January 09, 2026
 

src/Renderer/HtmlRenderer.php

@@ -360,7 +360,7 @@ public function renderCallStack(Throwable $t, array $trace = []): string
             $function = null;
             if (!empty($traceItem['function']) && $traceItem['function'] !== 'unknown') {
                 $function = $traceItem['function'];
-                if (!str_contains($function, '{closure}')) {
+                if (!str_contains($function, '{closure')) {
                     try {
                         if ($class !== null && class_exists($class)) {
                             $parameters = (new ReflectionMethod($class, $function))->getParameters();
@@ -570,6 +570,34 @@ public function removeAnonymous(string $value): string
         return $anonymousPosition !== false ? substr($value, 0, $anonymousPosition) : $value;
     }
 
+    /**
+     * Formats a trace function name for display.
+     *
+     * Handles PHP 8.4+ closure format `{closure:Context:line}` by extracting the definition context.
+     * For regular functions, prepends the class name when available.
+     */
+    public function formatTraceFunctionName(?string $class, string $function): string
+    {
+        // PHP 8.4+: {closure:Context:line} - already contains full definition context.
+        if (preg_match('/^\{closure:(.+):(\d+)\}$/', $function, $matches)) {
+            return '{closure} ' . $matches[1] . ':' . $matches[2];
+        }
+
+        // PHP < 8.4 namespaced closure: Namespace\{closure} - strip redundant namespace.
+        if (str_contains($function, '\\{closure')) {
+            if ($class !== null && $class !== 'Closure') {
+                return $this->removeAnonymous($class) . '::{closure}';
+            }
+            return $function;
+        }
+
+        if ($class === null || $class === 'Closure') {
+            return $function;
+        }
+
+        return $this->removeAnonymous($class) . '::' . $function;
+    }
+
     /**
      * Extracts a user-facing description from throwable class PHPDoc.
      *
@@ -745,12 +773,21 @@ private function renderCallStackItem(
         if ($file !== null && $line !== null) {
             $line--; // adjust line number from one-based to zero-based
             $lines = @file($file);
-            if ($line < 0 || $lines === false || ($lineCount = count($lines)) < $line) {
-                return '';
+            if ($line < 0 || $lines === false) {
+                if ($line < 0) {
+                    $line = null; // non-positive line has no valid source location to show
+                }
+                $lines = [];
+            } else {
+                $lineCount = count($lines);
+                if ($line <= $lineCount) {
+                    $half = (int) (($index === 1 ? $this->maxSourceLines : $this->maxTraceLines) / 2);
+                    $begin = $line - $half > 0 ? $line - $half : 0;
+                    $end = $line + $half < $lineCount ? $line + $half : $lineCount - 1;
+                } else {
+                    $lines = [];
+                }
             }
-            $half = (int) (($index === 1 ? $this->maxSourceLines : $this->maxTraceLines) / 2);
-            $begin = $line - $half > 0 ? $line - $half : 0;
-            $end = $line + $half < $lineCount ? $line + $half : $lineCount - 1;
         }
 
         return $this->renderTemplate($this->defaultTemplatePath . '/_call-stack-item.php', [

templates/_call-stack-item.php

@@ -62,7 +62,7 @@
                 <span class="function-info word-break">
                     <?php
                     echo $file === null ? "$index. " : '&mdash;&nbsp;';
-                    $function = $class === null ? $function : "{$this->removeAnonymous($class)}::$function";
+                    $function = $this->formatTraceFunctionName($class, $function);
 
                     echo '<span class="function">' . $this->htmlEncode($function) . '</span>';
                     echo '<span class="arguments">(';