Introduce Throwable.toStringWithTrace

#KT-37603

libraries/stdlib/js/src/kotlin/throwableExtensions.kt

@@ -5,6 +5,18 @@
 
 package kotlin
 
+/**
+ * Returns the detailed description of this throwable with its stack trace.
+ *
+ * The detailed description includes:
+ * - the short description (see [Throwable.toString]) of this throwable;
+ * - the complete stack trace;
+ * - detailed descriptions of the exceptions that were [suppressed][suppressedExceptions] in order to deliver this exception;
+ * - the detailed description of each throwable in the [Throwable.cause] chain.
+ */
+@SinceKotlin("1.4")
+public actual fun Throwable.toStringWithTrace(): String = buildString { dumpStackTraceTo("", "", this) }
+
 /**
  * Adds the specified exception to the list of exceptions that were
  * suppressed in order to deliver this exception.
@@ -29,3 +41,42 @@ public actual val Throwable.suppressedExceptions: List<Throwable>
     get() {
         return this.asDynamic()._suppressed?.unsafeCast<List<Throwable>>() ?: emptyList()
     }
+
+
+private fun Throwable.dumpStackTraceTo(indent: String, qualifier: String, target: StringBuilder) {
+    this.dumpSelfTrace(indent, qualifier, target)
+
+    var cause = this.cause
+    while (cause != null) {
+        // TODO: should skip common stack frames
+        cause.dumpSelfTrace(indent, "Caused by: ", target)
+        cause = cause.cause
+    }
+}
+
+private fun Throwable.dumpSelfTrace(indent: String, qualifier: String, target: StringBuilder) {
+    target.append(indent).append(qualifier)
+    val stack = this.asDynamic().stack as String?
+    if (stack != null) {
+        if (indent.isNotEmpty()) {
+            // indent stack, but avoid indenting exception message lines
+            val messageLines = 1 + (message?.count { c -> c == '\n' } ?: 0)
+            stack.lineSequence().forEachIndexed { index: Int, line: String ->
+                if (index >= messageLines) target.append(indent)
+                target.append(line).append("\n")
+            }
+        } else {
+            target.append(stack).append("\n")
+        }
+    } else {
+        target.append(this.toString()).append("\n")
+    }
+
+    val suppressed = suppressedExceptions
+    if (suppressed.isNotEmpty()) {
+        val suppressedIndent = indent + '\t'
+        for (s in suppressed) {
+            s.dumpStackTraceTo(suppressedIndent, "Suppressed: ", target)
+        }
+    }
+}