error: inlining failed in call to 'always_inline'

[lbussy]

I'm getting this error in an application that used to compile without issue on an older ArduinoJson 6.x version.

ArduinoJson Troubleshooter's report

1. The issue happens at compile time
2. The error is not in the list

In file included from .pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson/Array/ArrayIterator.hpp:8,
                 from .pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson/Array/ArrayRef.hpp:8,
                 from .pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson.hpp:17,
                 from .pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson.h:9,
                 from src\jsonconfig.h:27,
                 from src\jsonconfig.cpp:23:
.pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson/Variant/VariantRef.hpp: In member function 'typename ArduinoJson6180_D1::enable_if<((! ArduinoJson6180_D1::is_same<T, char*>::value) && (! ArduinoJson6180_D1::is_same<T, char>::value)), T>::type ArduinoJson6180_D1::VariantConstRef::as() const [with T = ArduinoJson6180_D1::VariantRef]':
.pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson/Variant/VariantRef.hpp:295:16: error: inlining failed in call to 'always_inline' 'ArduinoJson6180_D1::VariantConstRef::operator T() const [with T = ArduinoJson6180_D1::VariantRef]': function not inlinable
  295 |   FORCE_INLINE operator T() const {
      |                ^~~~~~~~
.pio\libdeps\d1_mini\ArduinoJson\src/ArduinoJson/Variant/VariantRef.hpp:253:34: note: called from here
  253 |     return Converter<T>::fromJson(*this);
      |            ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
Compiling .pio\build\d1_mini\src\uptime.cpp.o
*** [.pio\build\d1_mini\src\jsonconfig.cpp.o] Error 1

I'm more than happy to try to refine the issue, create a small fail case, etc., however, to rip it all out and re-write it would sort of remove any advantage your experience might bring. :)

If this error rings a bell with you, great! If not, I'll start commenting out swaths of code to figure out where I'm going sideways.

Updating bblanchon/ArduinoJson                6.18.0                             [Up-to-date]

Platform espressif8266
--------
Updating platformio/espressif8266             3.0.0                              [Up-to-date]
Updating platformio/toolchain-xtensa          2.100200.0 @ ~2.100200.0           [Up-to-date]
Updating platformio/framework-arduinoespressif8266 3.30000.210519 @ ~3.30000.0        [Up-to-date]

[bblanchon]

Hi @lbussy,

Thank you very much for reporting this error 👍
I currently don't manage to reproduce it.
Can you show me the relevant lines from jsonconfig.cpp?

Best regards,
Benoit

[lbussy]

I can/will - I was hoping you'd say "yeah you did X dummy!" and fix it. :)

I'm going to have to carve out a bunch of things to make a specific test to narrow it down. The errors I get always seem to point to the header that included ArduinoJson and rarely to the line causing the exception.

[lbussy]

Okay, found it. This is the functionality you helped me with previously. It's possible I made it work in a manner that was not intended and a patch broke me:

bool mergeJsonString(String newJson)
{
    DynamicJsonDocument doc(capacityDeserial);
    DeserializationError err = deserializeJson(doc, newJson);
    if (err)
        Serial.println(err.c_str());
    return mergeJsonObject(doc);
}

bool mergeJsonObject(JsonVariantConst src)
{
    DynamicJsonDocument doc(capacityDeserial);
    JsonObject root = doc.to<JsonObject>();
    config.save(root);
    if (merge(root, src))
    {
        config.load(root);
        saveFile();
        return true;
    }
    return false;
}

bool merge(JsonVariant dst, JsonVariantConst src)
{
    if (src.is<JsonObject>())
    {
        for (auto kvp : src.as<JsonObject>())
        {
            merge(dst.getOrAddMember(kvp.key()), kvp.value());
        }
    }
    else
    {
        dst.set(src);
    }
    return true;
}

I'm relatively certain it's in the bool merge(JsonVariant dst, JsonVariantConst src) function, although I am not certain why.

[bblanchon]

You did make a mistake, but it wasn't easy to spot!

src.as<JsonObject>() is not a valid conversion because src is a JsonVariantConst.
Indeed, you cannot get a read-write reference out of a read-only reference.
Instead, you must use src.as<JsonObjectConst>().

I added the dummy class InvalidConversion (declared but never defined) to get a more explicit compilation error:

In file included from .../ArduinoJson/Array/ArrayIterator.hpp:8:0,
                 from .../ArduinoJson/Array/ArrayRef.hpp:8,
                 from .../ArduinoJson.hpp:17,
                 from .../ArduinoJson.h:9,
                 from MyProgram.ino:9:
.../ArduinoJson/Variant/VariantRef.hpp: In instantiation of 'typename ArduinoJson6180_91::enable_if<((! ArduinoJson6180_91::is_same<T, char*>::value) && (! ArduinoJson6180_91::is_same<T, char>::value)), T>::type ArduinoJson6180_91::VariantConstRef::as() const [with T = ArduinoJson6180_91::ObjectRef; typename ArduinoJson6180_91::enable_if<((! ArduinoJson6180_91::is_same<T, char*>::value) && (! ArduinoJson6180_91::is_same<T, char>::value)), T>::type = ArduinoJson6180_91::ObjectRef]':
MyProgram.ino:37:44:   required from here
.../ArduinoJson/Variant/VariantRef.hpp:251:34: error: invalid use of incomplete type 'class ArduinoJson6180_91::InvalidConversion<ArduinoJson6180_91::VariantConstRef, ArduinoJson6180_91::ObjectRef>'
     return Converter<T>::fromJson(*this);
            ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In file included from .../ArduinoJson/Variant/VariantRef.hpp:14:0,
                 from .../ArduinoJson/Array/ArrayIterator.hpp:8,
                 from .../ArduinoJson/Array/ArrayRef.hpp:8,
                 from .../ArduinoJson.hpp:17,
                 from .../ArduinoJson.h:9,
                 from MyProgram.ino:9:
.../ArduinoJson/Variant/Converter.hpp:14:7: note: declaration of 'class ArduinoJson6180_91::InvalidConversion<ArduinoJson6180_91::VariantConstRef, ArduinoJson6180_91::ObjectRef>'
 class InvalidConversion;  // Error here? See https://arduinojson.org/v6/invalid-conversion/
       ^~~~~~~~~~~~~~~~~

[lbussy]

Ahhhhhhhhhhhhhhhhhh! I'm not sure how you keep it all straight! :)

Thank you very much for pointing that out!! By the way that link to https://arduinojson.org/v6/invalid-conversion/ is a 404.

[bblanchon]

InvalidConversion is available in ArduinoJson 6.18.1