From 4bd7b4d29e3ebb43cf6495c3d074eea25197e8dd Mon Sep 17 00:00:00 2001
From: "Earle F. Philhower, III" <earlephilhower@yahoo.com>
Date: Thu, 10 Feb 2022 13:22:00 -0800
Subject: [PATCH] Free String memory on assign of "" or clear()

Fixes #8485

Whenever the empty C string is assigned or the .clear() method
called, free any heap allocated with the String.
---
 cores/esp8266/WString.cpp | 2 +-
 cores/esp8266/WString.h   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/cores/esp8266/WString.cpp b/cores/esp8266/WString.cpp
index c6b3c6ae0a..9e77408887 100644
--- a/cores/esp8266/WString.cpp
+++ b/cores/esp8266/WString.cpp
@@ -258,7 +258,7 @@ String &String::operator =(String &&rval) noexcept {
 }
 
 String &String::operator =(const char *cstr) {
-    if (cstr)
+    if (cstr && cstr[0])
         copy(cstr, strlen(cstr));
     else
         invalidate();
diff --git a/cores/esp8266/WString.h b/cores/esp8266/WString.h
index d028c0abfb..ab9e241489 100644
--- a/cores/esp8266/WString.h
+++ b/cores/esp8266/WString.h
@@ -88,7 +88,7 @@ class String {
             return buffer() ? len() : 0;
         }
         void clear(void) {
-            setLen(0);
+            invalidate();
         }
         bool isEmpty(void) const {
             return length() == 0;