I'm currently trying to build a firmware from https://github.com/pycom/pycom-micropython-sigfox/tree/master/esp32 for my Wipy 2.0 but I always get an error during the build of bootloader.

I started from a fresh clone https://github.com/pycom/pycom-micropython-sigfox
Using pycom-esp-idf and the xtensa-esp32-elf toolchain.

I did the submodule update with success

~/esp32_B/pycom-micropython-sigfox/esp32$ git submodule update --init
Sous-module 'lib/axtls' (https://github.com/pfalcon/axtls) enregistré pour le chemin '../lib/axtls'
Sous-module 'lib/berkeley-db-1.xx' (https://github.com/pfalcon/berkeley-db-1.xx) enregistré pour le chemin '../lib/berkeley-db-1.xx'
Sous-module 'lib/libffi' (https://github.com/atgreen/libffi) enregistré pour le chemin '../lib/libffi'
Sous-module 'lib/lwip' (http://git.savannah.gnu.org/r/lwip.git) enregistré pour le chemin '../lib/lwip'
Clonage dans 'lib/axtls'...
remote: Counting objects: 2774, done.
remote: Total 2774 (delta 0), reused 0 (delta 0), pack-reused 2774
Réception d'objets: 100% (2774/2774), 3.47 MiB | 73.00 KiB/s, fait.
Résolution des deltas: 100% (2087/2087), fait.
Vérification de la connectivité... fait.
Chemin de sous-module '../lib/axtls' : '67d27df4b5d097e146599fc4fb160a2adcbf5632' extrait
Clonage dans 'lib/berkeley-db-1.xx'...
remote: Counting objects: 262, done.
remote: Compressing objects: 100% (121/121), done.
remote: Total 262 (delta 121), reused 262 (delta 121), pack-reused 0
Réception d'objets: 100% (262/262), 331.56 KiB | 67.00 KiB/s, fait.
Résolution des deltas: 100% (121/121), fait.
Vérification de la connectivité... fait.
Chemin de sous-module '../lib/berkeley-db-1.xx' : 'dab957dacddcbf6cbc85d42df62e189e4877bb72' extrait
Clonage dans 'lib/libffi'...
remote: Counting objects: 10883, done.
remote: Total 10883 (delta 0), reused 0 (delta 0), pack-reused 10882
Réception d'objets: 100% (10883/10883), 6.83 MiB | 54.00 KiB/s, fait.
Résolution des deltas: 100% (6773/6773), fait.
Vérification de la connectivité... fait.
Chemin de sous-module '../lib/libffi' : 'e9de7e35f2339598b16cbb375f9992643ed81209' extrait
Clonage dans 'lib/lwip'...
remote: Counting objects: 43712, done.
remote: Compressing objects: 100% (10861/10861), done.
remote: Total 43712 (delta 32866), reused 42970 (delta 32347)
Réception d'objets: 100% (43712/43712), 8.11 MiB | 29.00 KiB/s, fait.
Résolution des deltas: 100% (32866/32866), fait.
Vérification de la connectivité... fait.
Chemin de sous-module '../lib/lwip' : '5b8b5d459e7dd890724515bbfad86c705234f9ec' extrait

I also built mpy-cross sucessfully

~/esp32_B/pycom-micropython-sigfox/mpy-cross$ make all
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
mkdir -p build/genhdr
Generating build/genhdr/mpversion.h
GEN build/genhdr/qstr.i.last
GEN build/genhdr/qstr.split
GEN build/genhdr/qstrdefs.collected.h
QSTR updated
GEN build/genhdr/qstrdefs.generated.h
mkdir -p build/py/
mkdir -p build/py/../extmod/
mkdir -p build/py/../lib/embed/
mkdir -p build/py/../lib/utils/
CC ../py/mpstate.c
CC ../py/nlrx86.S
CC ../py/nlrx64.S
CC ../py/nlrthumb.c
CC ../py/nlrxtensa.S
CC ../py/nlrsetjmp.c
CC ../py/malloc.c
CC ../py/gc.c
CC ../py/qstr.c
CC ../py/vstr.c
CC ../py/mpprint.c
CC ../py/unicode.c
CC ../py/mpz.c
CC ../py/lexer.c
CC ../py/lexerstr.c
CC ../py/lexerunix.c
CC ../py/parse.c
CC ../py/scope.c
CC ../py/compile.c
CC ../py/emitcommon.c
CC ../py/emitbc.c
CC ../py/asmx64.c
CC ../py/emitnative.c
CC ../py/asmx86.c
CC ../py/emitnative.c
CC ../py/asmthumb.c
CC ../py/emitnative.c
CC ../py/emitinlinethumb.c
CC ../py/asmarm.c
CC ../py/emitnative.c
CC ../py/formatfloat.c
CC ../py/parsenumbase.c
CC ../py/parsenum.c
CC ../py/emitglue.c
CC ../py/runtime.c
CC ../py/runtime_utils.c
CC ../py/nativeglue.c
CC ../py/stackctrl.c
CC ../py/argcheck.c
CC ../py/warning.c
CC ../py/map.c
CC ../py/obj.c
CC ../py/objarray.c
CC ../py/objattrtuple.c
CC ../py/objbool.c
CC ../py/objboundmeth.c
CC ../py/objcell.c
CC ../py/objclosure.c
CC ../py/objcomplex.c
CC ../py/objdict.c
CC ../py/objenumerate.c
CC ../py/objexcept.c
CC ../py/objfilter.c
CC ../py/objfloat.c
CC ../py/objfun.c
CC ../py/objgenerator.c
CC ../py/objgetitemiter.c
CC ../py/objint.c
CC ../py/objint_longlong.c
CC ../py/objint_mpz.c
CC ../py/objlist.c
CC ../py/objmap.c
CC ../py/objmodule.c
CC ../py/objobject.c
CC ../py/objpolyiter.c
CC ../py/objproperty.c
CC ../py/objnone.c
CC ../py/objnamedtuple.c
CC ../py/objrange.c
CC ../py/objreversed.c
CC ../py/objset.c
CC ../py/objsingleton.c
CC ../py/objslice.c
CC ../py/objstr.c
CC ../py/objstrunicode.c
CC ../py/objstringio.c
CC ../py/objtuple.c
CC ../py/objtype.c
CC ../py/objzip.c
CC ../py/opmethods.c
CC ../py/sequence.c
CC ../py/stream.c
CC ../py/binary.c
CC ../py/builtinimport.c
CC ../py/builtinevex.c
CC ../py/modarray.c
CC ../py/modbuiltins.c
CC ../py/modcollections.c
CC ../py/modgc.c
CC ../py/modio.c
CC ../py/modmath.c
CC ../py/modcmath.c
CC ../py/modmicropython.c
CC ../py/modstruct.c
CC ../py/modsys.c
CC ../py/moduerrno.c
CC ../py/modthread.c
CC ../py/vm.c
CC ../py/bc.c
CC ../py/showbc.c
CC ../py/repl.c
CC ../py/smallint.c
CC ../py/frozenmod.c
CC ../py/../extmod/moductypes.c
CC ../py/../extmod/modujson.c
CC ../py/../extmod/modure.c
CC ../py/../extmod/moduzlib.c
CC ../py/../extmod/moduheapq.c
CC ../py/../extmod/moduhashlib.c
CC ../py/../extmod/modubinascii.c
CC ../py/../extmod/virtpin.c
CC ../py/../extmod/machine_mem.c
CC ../py/../extmod/machine_pinbase.c
CC ../py/../extmod/machine_pulse.c
CC ../py/../extmod/machine_i2c.c
CC ../py/../extmod/machine_spi.c
CC ../py/../extmod/modussl_axtls.c
CC ../py/../extmod/modussl_mbedtls.c
CC ../py/../extmod/modurandom.c
CC ../py/../extmod/modwebsocket.c
CC ../py/../extmod/modwebrepl.c
CC ../py/../extmod/modframebuf.c
CC ../py/../extmod/fsusermount.c
CC ../py/../extmod/vfs_fat.c
CC ../py/../extmod/vfs_fat_ffconf.c
CC ../py/../extmod/vfs_fat_diskio.c
CC ../py/../extmod/vfs_fat_file.c
CC ../py/../extmod/vfs_fat_lexer.c
CC ../py/../extmod/vfs_fat_misc.c
CC ../py/../extmod/utime_mphal.c
CC ../py/../extmod/uos_dupterm.c
CC ../py/../lib/embed/abort_.c
CC ../py/../lib/utils/printf.c
CC main.c
CC gccollect.c
LINK mpy-cross
text data bss dec hex filename
133884 792 904 135580 2119c mpy-cross

The environment variable for esp-idf path is defined

~/esp32_B/pycom-micropython-sigfox/esp32$ echo $ESP_IDF_PATH
/home/julien/esp32_B/pycom-esp-idf/

When I'm trying to build the firmware I got the following error:

~/esp32_B/pycom-micropython-sigfox/esp32$ make BOARD=WIPY -j5 TARGET=boot
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
CC bootloader/bootloader.c
CC bootloader/bootmgr.c
CC bootloader/mperror.c
CC bootloader/gpio.c
bootloader/gpio.c:14:23: fatal error: esp_types.h: No such file or directory
compilation terminated.
In file included from bootloader/bootloader.c:19:0:
bootloader/bootloader.h:18:34: fatal error: esp_flash_data_types.h: No such file or directory
compilation terminated.
bootloader/mperror.c:18:29: fatal error: heap_alloc_caps.h: No such file or directory
compilation terminated.
bootloader/bootmgr.c:18:29: fatal error: heap_alloc_caps.h: No such file or directory
compilation terminated.
../py/mkrules.mk:47: recipe for target 'build/WIPY/release/bootloader/gpio.o' failed
make: *** [build/WIPY/release/bootloader/gpio.o] Error 1
make: *** Attente des tâches non terminées....
../py/mkrules.mk:47: recipe for target 'build/WIPY/release/bootloader/bootmgr.o' failed
make: *** [build/WIPY/release/bootloader/bootmgr.o] Error 1
../py/mkrules.mk:47: recipe for target 'build/WIPY/release/bootloader/bootloader.o' failed
make: *** [build/WIPY/release/bootloader/bootloader.o] Error 1
../py/mkrules.mk:47: recipe for target 'build/WIPY/release/bootloader/mperror.o' failed
make: *** [build/WIPY/release/bootloader/mperror.o] Error 1

Does someone knows where the error could come from?