Using the latest Aduino 1.8.10 IDE and a Wemos D1 mini board with DHT22 sensor, I can include Thingspeak and upload the data (mulitifield) without any problem.
Using the exact same software and board I can also run a sketch wherein the Wemos acts as LANserver and is approachable using a mDNS address (.local) using the #include <ESP8266mDNS.h> and
#include <ESP8266WebServer.h> commands.
So all looks rosy.
However, when adding just the line #include <ThingSpeak.h> into the later sketch, it will not compile anymore and I get the error message
C:\Users\Pasal Laptop\Documents\Arduino\libraries\ThingSpeak\src/ThingSpeak.h:70:33: error: expected identifier before ‘-’ token
#define ERR_TIMEOUT -304 // Timeout waiting for server to respond
I am puzzled. What is wrong? Or is ThingSpeak not compatible with the two ESP8266 libraries?