undefined reference to `analogReference'

[tablatronix]

Basic Infos

• This issue complies with the issue POLICY doc.
• I have read the documentation at readthedocs and the issue is not addressed there.
• I have tested that the issue is present in current master branch (aka latest git).
• I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: [ESP-12|ESP-01|ESP-07|ESP8285 device|other]
• Core Version: latest
• Development Env: [Arduino IDE|Platformio|Make|other]
• Operating System: [Windows|Ubuntu|MacOS]

Settings in IDE

• Module: [Generic ESP8266 Module|Wemos D1 mini r2|Nodemcu|other]
• Flash Mode: [qio|dio|other]
• Flash Size: [4MB/1MB]
• lwip Variant: [v1.4|v2 Lower Memory|Higher Bandwidth]
• Reset Method: [ck|nodemcu]
• Flash Frequency: [40Mhz]
• CPU Frequency: [80Mhz|160MHz]
• Upload Using: [OTA|SERIAL]
• Upload Speed: [115200|other] (serial upload only)

Problem Description

undefined reference to 'analogReference' when compiling libs that use it.

[ Deviot 2.3.0.dev12 ] Starting...
Processing esp12e (platform: espressif8266; board: esp12e; framework: arduino)
--------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif8266/esp12e.html
PLATFORM: Espressif 8266 2.2.2 > Espressif ESP8266 ESP-12E
HARDWARE: ESP8266 80MHz, 80KB RAM, 4MB Flash
PACKAGES: toolchain-xtensa 2.40802.190218 (4.8.2), tool-esptool 1.413.0 (4.13), tool-esptoolpy 1.20600.0 (2.6.0), framework-arduinoespressif8266 2.20502.0 (2.5.2)
Converting basicntc.ino
LDF: Library Dependency Finder -> http://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 141 compatible libraries
Scanning dependencies...
Dependency Graph
|-- <thermistor> 1.0.2
Compiling .pio/build/esp12e/src/basicntc.ino.cpp.o
Linking .pio/build/esp12e/firmware.elf
/Users/shawn/.platformio/packages/toolchain-xtensa/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld: .pio/build/esp12e/lib23e/libthermistor_ID354.a(thermistor.cpp.o):(.text._ZN10THERMISTOR4readEv+0x34): undefined reference to `analogReference'
/Users/shawn/.platformio/packages/toolchain-xtensa/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/bin/ld: .pio/build/esp12e/lib23e/libthermistor_ID354.a(thermistor.cpp.o):(.text._ZN10THERMISTOR4readEv+0x6f): undefined reference to `analogReference'
collect2: error: ld returned 1 exit status
*** [.pio/build/esp12e/firmware.elf] Error 1
========================== [ERROR] Took 5.30 seconds ==========================

[Sat Aug 10 08:51:42 2019]

def exists in arduino.h

Looks like it was discussed but never implemented?
here #443

[tablatronix]

This is probably not fixable as there is no reference and tout must be floating which makes this mostly impossible. But fix it to throw a compiler warning or assert to prevent libraries from failing to compile.