Compile errors in ESPHome 2026.2.0-dev

[paulb-fr]

Thanks for this great project. I had some PCBs made up (at great expense!) but fitting out 2 AC indoor units has still come in less than the cost of a single Panasonic WIFI dongle, and they work great.

I have had to move to the DEV version of ESPHome in order to get access to the esp-idf ac_dimmer component for another project, but this means that I am no longer able to compile my Panasonic controllers. Fortunately HA allows both the production and dev versions of ESPHome to be installed simultaneously, although it makes for some long compile times if you switch back and forth as it has to re-download the entire thing (or so it seems). Once the 2026 release is out though, it will get problematic for anyone coming to this project for the first time.

The errors are:
`In member function 'void esphome::panasonic_ac::PanasonicAC::set_vertical_swing_select(esphome::select::Select*)':
src/esphome/components/panasonic_ac/esppac.cpp:

219:55: error: cannot convert 'esphome::panasonic_ac::PanasonicAC::set_vertical_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>'
to 'std::function<void(unsigned int)>&&'

this->vertical_swing_select_->add_on_state_callback([this](const std::string &value, size_t index) { esphome::panasonic_ac::PanasonicAC::set_vertical_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>

228:57: error: cannot convert 'esphome::panasonic_ac::PanasonicAC::set_horizontal_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>' to 'std::function<void(unsigned int)>&&'

cannot convert 'esphome::StringRef' to 'const char*'
251 | if (strcmp(this->get_custom_preset(), "Normal") != 0) {

256:51: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
256 | const char *fanMode = call.get_custom_fan_mode();

299:48: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
299 | const char *preset = call.get_custom_preset();

esppac_wlan.cpp:113:51: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
113 | const char *fanMode = call.get_custom_fan_mode();

167:48: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
167 | const char *preset = call.get_custom_preset();`

I would look into it myself, but this is way beyond my capabilities.

Regards,

• Paul

[EDIT - reduce clutter in error messages]

[Jalakas]

add_on_state_callback()

I had same compile time error, "AI" helped me to get over it.
Jalakas@4b9fe77
Warning: No runtime tests done, not a pull request, just for inspiration.

Could you fix your error log formatting also? It's hard to understand other problems.

[paulb-fr]

Thanks for the comments @Jalakas. I have attempted to reduce the simple copy-paste from ESPHome to the bare minimum.

I am guessing that this has something to do with adding c_str() in a few places? Just need to work out how to get a fork/copy of this repository into my HA Green then I can start tinkering.

[Jalakas]

Just need to work out how to get a fork/copy

Yes, caching can also be tricky.
I managed to test my code: force (new) git commit -> get new hash -> use this hash in esphome.
For example:

external_components:
  - source:
      type: git
      url: https://github.com/Jalakas/esphome-panasonic-ac
      ref: 4b9fe77
      path: components
    components:
      - panasonic_ac

[gschmidl]

This now happens in the official release, so thanks for this temporary fix!

[khenderick]

@Jalakas Thanks for this patch. Would you mind creating a PR of your changes? This might make it easier for Dominik to accept & merge it.

[chwdt]

I have created a PR #175 for this issue and Select::current_option() returning a StringRef.

[lollo78]

For me (ESPHOME 2026.1.0) I have this error during compiling:

src/esphome/components/panasonic_ac/esppac.cpp: In member function 'void esphome::panasonic_ac::PanasonicAC::set_vertical_swing_select(esphome::select::Select*)':
src/esphome/components/panasonic_ac/esppac.cpp:219:55: error: cannot convert 'esphome::panasonic_ac::PanasonicAC::set_vertical_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>' to 'std::function<void(unsigned int)>&&'
  219 |   this->vertical_swing_select_->add_on_state_callback([this](const std::string &value, size_t index) {
      |                                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                       |
      |                                                       esphome::panasonic_ac::PanasonicAC::set_vertical_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>
  220 |     if (value == this->vertical_swing_state_)
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~          
  221 |       return;
      |       ~~~~~~~                                          
  222 |     this->on_vertical_swing_change(value);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~             
  223 |   });
      |   ~                                                    
In file included from src/esphome/components/panasonic_ac/esppac.h:4,
                 from src/esphome/components/panasonic_ac/esppac.cpp:1:
src/esphome/components/select/select.h:81:60: note:   initializing argument 1 of 'void esphome::select::Select::add_on_state_callback(std::function<void(unsigned int)>&&)'
   81 |   void add_on_state_callback(std::function<void(size_t)> &&callback);
      |                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
src/esphome/components/panasonic_ac/esppac.cpp: In member function 'void esphome::panasonic_ac::PanasonicAC::set_horizontal_swing_select(esphome::select::Select*)':
src/esphome/components/panasonic_ac/esppac.cpp:228:57: error: cannot convert 'esphome::panasonic_ac::PanasonicAC::set_horizontal_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>' to 'std::function<void(unsigned int)>&&'
  228 |   this->horizontal_swing_select_->add_on_state_callback([this](const std::string &value, size_t index) {
      |                                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      |                                                         |
      |                                                         esphome::panasonic_ac::PanasonicAC::set_horizontal_swing_select(esphome::select::Select*)::<lambda(const std::string&, size_t)>
  229 |     if (value == this->horizontal_swing_state_)
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~          
  230 |       return;
      |       ~~~~~~~                                            
  231 |     this->on_horizontal_swing_change(value);
      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~             
  232 |   });
      |   ~                                                      
src/esphome/components/select/select.h:81:60: note:   initializing argument 1 of 'void esphome::select::Select::add_on_state_callback(std::function<void(unsigned int)>&&)'
   81 |   void add_on_state_callback(std::function<void(size_t)> &&callback);
      |                              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
*** [.pioenvs/climatizzatore-camera/src/esphome/components/panasonic_ac/esppac.cpp.o] Error 1
src/esphome/components/panasonic_ac/esppac_cnt.cpp: In member function 'virtual void esphome::panasonic_ac::CNT::PanasonicACCNT::control(const esphome::climate::ClimateCall&)':
src/esphome/components/panasonic_ac/esppac_cnt.cpp:251:39: error: cannot convert 'esphome::StringRef' to 'const char*'
  251 |     if (strcmp(this->get_custom_preset(), "Normal") != 0) {
      |                ~~~~~~~~~~~~~~~~~~~~~~~^~
      |                                       |
      |                                       esphome::StringRef
In file included from /data/cache/platformio/packages/toolchain-riscv32-esp/riscv32-esp-elf/include/c++/14.2.0/cstring:43,
                 from src/esphome/core/helpers.h:6,
                 from src/esphome/core/component.h:8,
                 from src/esphome/components/climate/climate.h:3,
                 from src/esphome/components/panasonic_ac/esppac_cnt.h:1,
                 from src/esphome/components/panasonic_ac/esppac_cnt.cpp:1:
/data/cache/platformio/packages/toolchain-riscv32-esp/riscv32-esp-elf/include/string.h:36:18: note:   initializing argument 1 of 'int strcmp(const char*, const char*)'
   36 | int      strcmp (const char *, const char *);
      |                  ^~~~~~~~~~~~
src/esphome/components/panasonic_ac/esppac_cnt.cpp:256:51: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
  256 |     const char *fanMode = call.get_custom_fan_mode();
      |                           ~~~~~~~~~~~~~~~~~~~~~~~~^~
      |                                                   |
      |                                                   esphome::StringRef
src/esphome/components/panasonic_ac/esppac_cnt.cpp:299:48: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
  299 |     const char *preset = call.get_custom_preset();
      |                          ~~~~~~~~~~~~~~~~~~~~~~^~
      |                                                |
      |                                                esphome::StringRef
*** [.pioenvs/climatizzatore-camera/src/esphome/components/panasonic_ac/esppac_cnt.cpp.o] Error 1
src/esphome/components/panasonic_ac/esppac_wlan.cpp: In member function 'virtual void esphome::panasonic_ac::WLAN::PanasonicACWLAN::control(const esphome::climate::ClimateCall&)':
src/esphome/components/panasonic_ac/esppac_wlan.cpp:113:51: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
  113 |     const char *fanMode = call.get_custom_fan_mode();
      |                           ~~~~~~~~~~~~~~~~~~~~~~~~^~
      |                                                   |
      |                                                   esphome::StringRef
src/esphome/components/panasonic_ac/esppac_wlan.cpp:167:48: error: cannot convert 'esphome::StringRef' to 'const char*' in initialization
  167 |     const char *preset = call.get_custom_preset();
      |                          ~~~~~~~~~~~~~~~~~~~~~~^~
      |                                                |
      |                                                esphome::StringRef
*** [.pioenvs/climatizzatore-camera/src/esphome/components/panasonic_ac/esppac_wlan.cpp.o] Error 1
========================= [FAILED] Took 183.87 seconds =========================
==== [ERROR] /config/esphome/climatizzatore-camera.yaml ====

[CSchlipp]

Just need to work out how to get a fork/copy

Yes, caching can also be tricky. I managed to test my code: force (new) git commit -> get new hash -> use this hash in esphome.

One can set a refresh period on external components, telling esphome how frequently to update it from the repo:

external_components:
  source: github://DomiStyle/esphome-panasonic-ac
  components: [panasonic_ac]
  refresh: 60s

Ref. https://esphome.io/components/external_components/#refresh

[paulb-fr]

Trying to compile with 2026.1.0 and this bit of yaml still gives me the error "cannot convert 'esphome::StringRef' to 'const char*'" below in a number of places.

external_components:
  - source:
      type: git
      url: https://github.com/Jalakas/esphome-panasonic-ac
      path: components
    components:
      - panasonic_ac
    refresh: 60s

esppac_wlan.cpp:113:51
    const char *fanMode = call.get_custom_fan_mode();

esppac_wlan.cpp:167:48
    const char *preset = call.get_custom_preset();

esppac_cnt.cpp:250:39
    if (strcmp(this->get_custom_preset(), "Normal") != 0) {

esppac_cnt.cpp:255:51
    const char *fanMode = call.get_custom_fan_mode();

esppac_cnt.cpp:298:48
    const char *preset = call.get_custom_preset();

[Jalakas]

Trying to compile with 2026.1.0 and this bit of yaml still gives me the error "cannot convert 'esphome::StringRef' to 'const char*'" below in a number of places.

external_components:
  - source:
      type: git
      url: https://github.com/Jalakas/esphome-panasonic-ac

Mine was just example. You should test this url: https://github.com/chwdt/esphome-panasonic-ac
and comment your test results in this pull request: #175

[paulb-fr]

Mine was just example. You should test this url: https://github.com/chwdt/esphome-panasonic-ac and comment your test results in this pull request: #175

And as if by magic it all starts working :) Thanks @Jalakas!