An ESP8266mDNS related build failure

[bebo-dot-dev]

I hope someone can make sense of this :)

I develop in Eclipse with the Arduino Eclipse extension, I've updated from v2.1.0 -> v2.3.0 and code that did build previously no longer builds.

There seems to be some problem with how ARDUINO_BOARD is being defined. I think I've worked out that this is related to what's defined in boards.txt and I'm trying to use the "Generic ESP8266 Module" profile for an ESP12F board which means the folllowing is defined in platform.txt for this profile: generic.build.board=ESP8266_ESP01

I've created a bare bones new project bringing in the ESP8266mDNS library code and the build problem exists there too so it seems like this is an environmental problem.

This is the actual build error I see:
/home/joe/.arduino15/packages/esp8266/hardware/esp8266/2.3.0/libraries/ESP8266mDNS/ESP8266mDNS.cpp: In member function 'void MDNSResponder::enableArduino(uint16_t, bool)': <command-line>:0:15: error: 'ESP8266_ESP01' was not declared in this scope /home/joe/.arduino15/packages/esp8266/hardware/esp8266/2.3.0/libraries/ESP8266mDNS/ESP8266mDNS.cpp:841:44: note: in expansion of macro 'ARDUINO_BOARD' addServiceTxt("arduino", "tcp", "board", ARDUINO_BOARD);

Does anyone have a clue what's wrong here?

Thanks
Joe

[bebo-dot-dev]

A bit more info: ARDUINO_BOARD is #defined as a fallback in ESP8266mDNS.h here: https://github.com/esp8266/Arduino/blob/master/libraries/ESP8266mDNS/ESP8266mDNS.h#L49-#L52

If I comment out the #ifndef / #endif lines here leaving ARDUINO_BOARD hard defined as "generic", code then builds fine which tells me that under normal circumstances ARDUINO_BOARD is already defined in the environment as ESP8266_ESP01 and this is a symbol not recognized at build time..I expect that's because ESP8266_ESP01 is not recognized as a string literal like "generic"

I note the comment:

//this should be defined at build time

..here https://github.com/esp8266/Arduino/blob/master/libraries/ESP8266mDNS/ESP8266mDNS.h#L49 which is all well and good but it doesn't say where the ARDUINO_BOARD symbol should be defined or what to do when it seemingly gets defined improperly in Eclipse

[me-no-dev]

that is defined at build time in platform.txt here And you should maybe file a report to the maintainer of the plugin about this problem.

[bebo-dot-dev]

Thanks for the heads up I've raised a new issue over here: Sloeber/arduino-eclipse-plugin#493

[bebo-dot-dev]

After a lengthy investigation around the Eclipse Arduino plug-in code I've come to the conclusion that it's actually doing the right thing and the problem is right here where I was first pointed to.

With the platform.txt recipe config as it stands right now, we end up with a generated make file that writes out the gcc -D option like so:
-DARDUINO_BOARD="ESP8266_ESP01"

..which on the face of it looks ok, but it's not because the gcc pre-processor ends up generating code that looks like this in the .o object file:

addServiceTxt("arduino", "tcp", "board", ESP8266_ESP01);
note the missing quotes around ESP8266_ESP01 which results in the build failure

It's an easy enough fix though - we just need escaped quotes in platform.txt which results in the desired effect e.g. in platform.txt:
-DARDUINO_BOARD=\"{build.board}\"

resulting in this within the generated make file:
-DARDUINO_BOARD=\"ESP8266_ESP01\"

which results in this compiled code in the object file and a successful build:
addServiceTxt("arduino", "tcp", "board", "ESP8266_ESP01");
hurray a quoted string :)

If we agree this is the correct fix I'll create the pull request

Thanks
Joe

[jantje]

Mind that from experience I know the quotes are treated differently depending on OS. So you might need the .windows .linux extensions to get it working on all oses

[jantje]

I double checked. The \ is needed in windows but as the arduino IDE runs in some sort of linux simulation it is not needed there.
I assume that the current platform.txt works in mac, linux and windows with the arduino IDE, but with the arduino eclipse plugin called sloeber it wil only work on mac and linux.
Adding the \ would make the Arduino IDE to fail in all OS'es.
So I think we are back to Sloeber/arduino-eclipse-plugin#493

[bebo-dot-dev]

I agree good spot.

Adding escaping backslashes -DARDUINO_BOARD=\"{build.board}\" into platform.txt makes it work fine for the arduino eclipse plugin on linux but having tested compiling a small project in the arduino IDE, it fails to compile on linux with this error "stray '' in program addServiceTxt("arduino", "tcp", "board", ARDUINO_BOARD);" and the resulting pre-processor generated code is broken:
addServiceTxt("arduino", "tcp", "board", \"ESP8266_ESP01\");

I'm afraid I can't test windows at all here but I think we know enough to say that the escaping backslashes in platform.txt is not the right fix for this problem.

[jantje]

I'm a bit confused here. Does it work in the Arduino IDE "out of the box"?
Because my comments are on windows (if it works with the arduino ide it should work with the arduino eclipse plugin named sloeber on linux and mac)

This because Arduino uses the same appoach for build.usb_product for the due (and other boards)

arduino_due_x_dbg.build.usb_product="Arduino Due"
arduino_due_x_dbg.build.extra_flags=-D__SAM3X8E__ -mthumb {build.usb_flags}
build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} -DUSBCON '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'
recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.c.flags} -mcpu={build.mcu} -mthumb -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} {compiler.c.extra_flags} {build.extra_flags} {compiler.libsam.c.flags} {includes} "{source_file}" -o "{object_file}"

giving
recipe.c.o.pattern=..... '-DUSB_PRODUCT="Arduino Due"' ....

The link you refer to contains
-DARDUINO_BOARD="{build.board}"
but that should be
'-DARDUINO_BOARD="{build.board}"'
For the Arduino IDE.
implying it will not work in the Arduino IDE; unless some custom hardcoding has been done in the Arduino IDE to make this work.

[bebo-dot-dev]

It does indeed work in the Arduino IDE v1.6.8 'out of the box' and I guess the Arduino IDE is where ESP8266 arduino core maintainers generally focus their testing efforts to be happy it works for the bulk of the user / dev population.

-DARDUINO_BOARD="{build.board}"
I'm not sure where the difference lies but I can say without shadow of a doubt that we definitely have different behaviour in the toolchain between how the Arduino IDE and pre-processor interprets this -D compiler option on linux and how the eclipse arduino plugin interprets it.

There are no outer quotes around -DARDUINO_BOARD="{build.board}" as you can see in the source: https://github.com/esp8266/Arduino/blob/master/platform.txt#L73-L83
but this is working in the Arduino IDE and not working in the Eclipse Arduino plugin

[jantje]

I'm not sure where the difference lies but I can say without shadow of a doubt that we definitely have different behaviour in the toolchain between how the Arduino IDE and pre-processor interprets -DARDUINO_BOARD="{build.board}" on linux and how the Eclipse arduino plugin interprets it.

It is actually the command line that interprets differently.
My brain can't nail this behaviour. I'll try this on my windows system to see what it gives.

[bebo-dot-dev]

Ok thanks sounds good - good to hear you have a way to test windows there

[bebo-dot-dev]

Here's the minimal ESP8266 core sketch that doesn't compile with the eclipse arduino plugin and works fine in the arduino IDE:

#include "Arduino.h"
#include <ESP8266mDNS.h>

void setup()
{
    MDNS.addService("http", "tcp", 80);
}


void loop()
{

}