Where is tcp.h?

This is for an esp8266 project that uses EasyAsyncTCP. In EasyAsyncTCP.cpp they `#include "lwip/tcp.h"`. But I can't figure out where that file is. I've found a tcp.h in the following directories on my c drive:

• c:\Program Files (x86)\Arduino\hardware\arduino\avr\firmwares\wifishield\wifiHD\src\SOFTWARE_FRAMEWORK\SERVICES\LWIP\lwip-1.3.2\src\include\lwip
• c:\Program Files (x86)\Arduino\libraries\WiFi\extras\wifiHD\src\SOFTWARE_FRAMEWORK\SERVICES\LWIP\lwip-1.3.2\src\include\lwip
• c:\Users\me\AppData\Local\Arduino15\packages\esp32\hardware\esp32\1.0.2\tools\sdk\include\lwip\lwip
• c:\Users\me\AppData\Local\Arduino15\packages\esp32\hardware\esp32\1.0.2\tools\sdk\include\lwip\lwip\prot
• c:\Users\me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip\include\lwip
• c:\Users\me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip2\include\lwip
• c:\Users\me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip2\include\lwip\prot

but so far I've only tested the first two. I've tested them by either straight up deleting the directory and using the `#error got here` directive. No matter what I do my project builds. So I think I must either have the wrong file or it doesn't rebuild the entire thing.

How can I determine which tcp.h my program is including?

• do you see the esp8266 folders. one of them it is. LWIP version is selected in Tools menu – Juraj Sep 28 '19 at 17:23
• yes! thank you. – Sean McHugh Sep 28 '19 at 17:30

While this isn't the right way of doing it I'm sharing the way that I figured it out.

Step1:

cd c:\

dir tcp.h /s

c:\Program Files (x86)\Arduino\hardware\arduino\avr\firmwares\wifishield\wifiHD\src\SOFTWARE_FRAMEWORK\SERVICES\LWIP\lwip-1.3.2\src\include\lwip

c:\Program Files (x86)\Arduino\libraries\WiFi\extras\wifiHD\src\SOFTWARE_FRAMEWORK\SERVICES\LWIP\lwip-1.3.2\src\include\lwip

c:\c:\Users\Me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip2\include\lwip\protUsers\Me\AppData\Local\Arduino15\packages\esp32\hardware\esp32\1.0.2\tools\sdk\include\lwip\lwip

c:\Users\Me\AppData\Local\Arduino15\packages\esp32\hardware\esp32\1.0.2\tools\sdk\include\lwip\lwip\prot

c:\Users\Me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip\include\lwip

c:\Users\Me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip2\include\lwip

Step2:

I went through and tested each one. It was... `C:\Users\Me\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.5.2\tools\sdk\lwip2\include\lwip\tcp.h`