Fix comments: ESP8266 logging uses Serial, not ets_printf

esphome/components/esp8266/__init__.py

@@ -264,7 +264,9 @@ async def to_code(config):
 
     # Wrap FILE*-based printf functions to eliminate newlib's _vfiprintf_r
     # (~1.6 KB). See printf_stubs.cpp for implementation.
-    if not config.get(CONF_ENABLE_FULL_PRINTF):
+    if config.get(CONF_ENABLE_FULL_PRINTF):
+        cg.add_define("USE_FULL_PRINTF")
+    else:
         for symbol in ("vprintf", "printf", "fprintf"):
             cg.add_build_flag(f"-Wl,--wrap={symbol}")
 

esphome/components/esp8266/printf_stubs.cpp

@@ -3,14 +3,14 @@
  *
  * The ESP8266 Arduino framework and libraries may reference printf(),
  * vprintf(), and fprintf() which pull in newlib's _vfprintf_r (~900 bytes).
- * ESPHome never uses these — all logging goes through ets_printf/ets_vsnprintf
- * directly, so the libc FILE*-based printf path is dead code.
+ * ESPHome never uses these — all logging writes directly to the UART via
+ * Arduino's Serial, so the libc FILE*-based printf path is dead code.
  *
  * These stubs redirect through vsnprintf() (which is already in the binary
  * for ESPHome's logging) and fwrite(), allowing the linker to dead-code
  * eliminate _vfprintf_r.
  *
- * Saves ~900 bytes of flash.
+ * Saves ~1.6 KB of flash.
  */
 
 #if defined(USE_ESP8266) && !defined(USE_FULL_PRINTF)
@@ -22,8 +22,8 @@ namespace esphome::esp8266 {}
 
 static constexpr size_t PRINTF_BUFFER_SIZE = 256;
 
-// These stubs are essentially dead code at runtime — ESPHome uses ets_printf
-// for logging, and the Arduino core's Serial.printf() has its own implementation.
+// These stubs are essentially dead code at runtime — ESPHome writes directly
+// to the UART via Arduino's Serial, and Serial.printf() has its own implementation.
 // The buffer overflow check is purely defensive and should never trigger.
 static int write_printf_buffer(FILE *stream, char *buf, int len) {
   if (len < 0) {