Unable to get FMT_COMPILE to compile on ESP32

[summivox]

Platform: https://github.com/espressif/esp-idf

Compiler:

$ xtensa-esp32-elf-g++ --version
xtensa-esp32-elf-g++ (crosstool-NG esp-2020r3) 8.4.0
Copyright (C) 2018 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Code:

auto result = fmt::format(FMT_COMPILE("{}"), 12345);

Expected Result:
Code compiles.

Actual Result:
Code does not compile. Error message:

$ cmake
[1/9] Performing build step for 'bootloader'
ninja: no work to do.
[2/7] Building CXX object esp-idf/main/CMakeFiles/__idf_main.dir/app_main.cpp.obj
FAILED: esp-idf/main/CMakeFiles/__idf_main.dir/app_main.cpp.obj 
/home/summivox/.espressif/tools/xtensa-esp32-elf/esp-2020r3-8.4.0/xtensa-esp32-elf/bin/xtensa-esp32-elf-g++  -DHAVE_CONFIG_H -DMBEDTLS_CONFIG_FILE=\"mbedtls/esp_config.h\" -DUNITY_INCLUDE_CONFIG_H -DWITH_POSIX -Iconfig -I../main -I/home/summivox/lib/esp-idf/components/newlib/platform_include -I/home/summivox/lib/esp-idf/components/freertos/include -I/home/summivox/lib/esp-idf/components/freertos/port/xtensa/include -I/home/summivox/lib/esp-idf/components/esp_hw_support/include -I/home/summivox/lib/esp-idf/components/esp_hw_support/port/esp32/. -I/home/summivox/lib/esp-idf/components/heap/include -I/home/summivox/lib/esp-idf/components/log/include -I/home/summivox/lib/esp-idf/components/lwip/include/apps -I/home/summivox/lib/esp-idf/components/lwip/include/apps/sntp -I/home/summivox/lib/esp-idf/components/lwip/lwip/src/include -I/home/summivox/lib/esp-idf/components/lwip/port/esp32/include -I/home/summivox/lib/esp-idf/components/lwip/port/esp32/include/arch -I/home/summivox/lib/esp-idf/components/soc/include -I/home/summivox/lib/esp-idf/components/soc/esp32/. -I/home/summivox/lib/esp-idf/components/soc/esp32/include -I/home/summivox/lib/esp-idf/components/hal/esp32/include -I/home/summivox/lib/esp-idf/components/hal/include -I/home/summivox/lib/esp-idf/components/esp_rom/include -I/home/summivox/lib/esp-idf/components/esp_rom/esp32 -I/home/summivox/lib/esp-idf/components/esp_common/include -I/home/summivox/lib/esp-idf/components/esp_system/include -I/home/summivox/lib/esp-idf/components/esp32/include -I/home/summivox/lib/esp-idf/components/driver/include -I/home/summivox/lib/esp-idf/components/driver/esp32/include -I/home/summivox/lib/esp-idf/components/esp_ringbuf/include -I/home/summivox/lib/esp-idf/components/efuse/include -I/home/summivox/lib/esp-idf/components/efuse/esp32/include -I/home/summivox/lib/esp-idf/components/xtensa/include -I/home/summivox/lib/esp-idf/components/xtensa/esp32/include -I/home/summivox/lib/esp-idf/components/espcoredump/include -I/home/summivox/lib/esp-idf/components/esp_timer/include -I/home/summivox/lib/esp-idf/components/esp_ipc/include -I/home/summivox/lib/esp-idf/components/esp_pm/include -I/home/summivox/lib/esp-idf/components/vfs/include -I/home/summivox/lib/esp-idf/components/esp_wifi/include -I/home/summivox/lib/esp-idf/components/esp_wifi/esp32/include -I/home/summivox/lib/esp-idf/components/esp_event/include -I/home/summivox/lib/esp-idf/components/esp_netif/include -I/home/summivox/lib/esp-idf/components/esp_eth/include -I/home/summivox/lib/esp-idf/components/tcpip_adapter/include -I/home/summivox/lib/esp-idf/components/app_trace/include -I/home/summivox/lib/esp-idf/components/mbedtls/port/include -I/home/summivox/lib/esp-idf/components/mbedtls/mbedtls/include -I/home/summivox/lib/esp-idf/components/mbedtls/esp_crt_bundle/include -I/home/summivox/lib/esp-idf/components/bootloader_support/include -I/home/summivox/lib/esp-idf/components/app_update/include -I/home/summivox/lib/esp-idf/components/spi_flash/include -I/home/summivox/lib/esp-idf/components/nvs_flash/include -I/home/summivox/lib/esp-idf/components/pthread/include -I/home/summivox/lib/esp-idf/components/esp_gdbstub/include -I/home/summivox/lib/esp-idf/components/esp_gdbstub/xtensa -I/home/summivox/lib/esp-idf/components/esp_gdbstub/esp32 -I/home/summivox/lib/esp-idf/components/wpa_supplicant/include -I/home/summivox/lib/esp-idf/components/wpa_supplicant/port/include -I/home/summivox/lib/esp-idf/components/wpa_supplicant/include/esp_supplicant -I/home/summivox/lib/esp-idf/components/perfmon/include -I/home/summivox/lib/esp-idf/components/asio/asio/asio/include -I/home/summivox/lib/esp-idf/components/asio/port/include -I/home/summivox/lib/esp-idf/components/cbor/port/include -I/home/summivox/lib/esp-idf/components/unity/include -I/home/summivox/lib/esp-idf/components/unity/unity/src -I/home/summivox/lib/esp-idf/components/cmock/CMock/src -I/home/summivox/lib/esp-idf/components/coap/port/include -I/home/summivox/lib/esp-idf/components/coap/port/include/coap -I/home/summivox/lib/espummivox/lib/esp-idf/components/coap/libcoap/include/coap2 -I/home/summivox/lib/esp-idf/components/console -I/home/summivox/lib/esp-idf/components/nghttp/port/include -I/home/summivox/lib/esp-idf/components/nghttp/nghttp2/lib/includes -I/home/summivox/lib/esp-idf/components/esp-tls -I/home/summivox/lib/esp-idf/components/esp-tls/esp-tls-crypto -I/home/summivox/lib/esp-idf/components/esp_adc_cal/include -I/home/summivox/lib/esp-idf/components/esp_hid/include -I/home/summivox/lib/esp-idf/components/tcp_transport/include -I/home/summivox/lib/esp-idf/components/esp_http_client/include -I/home/summivox/lib/esp-idf/components/esp_http_server/include -I/home/summivox/lib/esp-idf/components/esp_https_ota/include -I/home/summivox/lib/esp-idf/components/esp_littlefs/src -I/home/summivox/lib/esp-idf/components/esp_littlefs/include -I/home/summivox/lib/esp-idf/components/protobuf-c/protobuf-c -I/home/summivox/lib/esp-idf/components/protocomm/include/common -I/home/summivox/lib/esp-idf/components/protocomm/include/security -I/home/summivox/lib/esp-idf/components/protocomm/include/transports -I/home/summivox/lib/esp-idf/components/mdns/include -I/home/summivox/lib/esp-idf/components/esp_local_ctrl/include -I/home/summivox/lib/esp-idf/components/sdmmc/include -I/home/summivox/lib/esp-idf/components/esp_serial_slave_link/include -I/home/summivox/lib/esp-idf/components/esp_websocket_client/include -I/home/summivox/lib/esp-idf/components/expat/expat/expat/lib -I/home/summivox/lib/esp-idf/components/expat/port/include -I/home/summivox/lib/esp-idf/components/wear_levelling/include -I/home/summivox/lib/esp-idf/components/fatfs/diskio -I/home/summivox/lib/esp-idf/components/fatfs/vfs -I/home/summivox/lib/esp-idf/components/fatfs/src -I/home/summivox/lib/esp-idf/components/freemodbus/common/include -I/home/summivox/lib/esp-idf/components/idf_test/include -I/home/summivox/lib/esp-idf/components/idf_test/include/esp32 -I/home/summivox/lib/esp-idf/components/jsmn/include -I/home/summivox/lib/esp-idf/components/json/cJSON -I/home/summivox/lib/esp-idf/components/libsodium/libsodium/src/libsodium/include -I/home/summivox/lib/esp-idf/components/libsodium/port_include -I/home/summivox/lib/esp-idf/components/mqtt/esp-mqtt/include -I/home/summivox/lib/esp-idf/components/openssl/include -I/home/summivox/lib/esp-idf/components/spiffs/include -I/home/summivox/lib/esp-idf/components/ulp/include -I/home/summivox/lib/esp-idf/components/wifi_provisioning/include -I../components/fmtlib/fmt/include -I../components/minmea/minmea -mlongcalls -Wno-frame-address   -ffunction-sections -fdata-sections -fstrict-volatile-bitfields -Wall -Werror=all -Wno-error=unused-function -Wno-error=unused-but-set-variable -Wno-error=unused-variable -Wno-error=deprecated-declarations -Wextra -Wno-unused-parameter -Wno-sign-compare -ggdb -O2 -std=gnu++11 -fno-exceptions -fno-rtti -D_GNU_SOURCE -DIDF_VER=\"v4.3-dev-2398-g2bfdd036b-dirty\" -DESP_PLATFORM -std=gnu++2a -MD -MT esp-idf/main/CMakeFiles/__idf_main.dir/app_main.cpp.obj -MF esp-idf/main/CMakeFiles/__idf_main.dir/app_main.cpp.obj.d -o esp-idf/main/CMakeFiles/__idf_main.dir/app_main.cpp.obj -c ../main/app_main.cpp
In file included from ../main/app_main.cpp:10:
../components/fmtlib/fmt/include/fmt/compile.h: In instantiation of 'constexpr auto fmt::v7::detail::compile_format_string(S) [with Args = fmt::v7::detail::type_list<int>; unsigned int POS = 0; int ID = 0; S = MainTask(void*)::<lambda()>::FMT_COMPILE_STRING]':
../components/fmtlib/fmt/include/fmt/compile.h:598:72:   required from 'constexpr auto fmt::v7::detail::compile(S) [with Args = {int}; S = MainTask(void*)::<lambda()>::FMT_COMPILE_STRING; typename std::enable_if<(fmt::v7::is_compile_string<S>::value || fmt::v7::detail::is_compiled_string<S>::value), int>::type <anonymous> = 0]'
../components/fmtlib/fmt/include/fmt/compile.h:677:53:   required from 'std::__cxx11::basic_string<typename S::char_type> fmt::v7::format(const S&, Args&& ...) [with S = MainTask(void*)::<lambda()>::FMT_COMPILE_STRING; Args = {int}; typename std::enable_if<fmt::v7::detail::is_compiled_string<S>::value, int>::type <anonymous> = 0; typename S::char_type = char; typename Context::char_type = char]'
../main/app_main.cpp:63:48:   required from here
../components/fmtlib/fmt/include/fmt/compile.h:558:58: error: exception handling disabled, use -fexceptions to enable
       throw format_error("unmatched '{' in format string");
                                                          ^
ninja: build stopped: subcommand failed.
The terminal process terminated with exit code: 1.

Workaround:

auto result = fmt::format(fmt::compile("{}"), 12345);

This does compile, but complains about fmt::compile being deprecated.

Investigation:
Here:

fmt/include/fmt/compile.h

Line 553 in 373262f

constexpr auto compile_format_string(S format_str) {

Even though I had no prior experience with debugging constexpr stuff in compile time, after inserting some "if (...) throw ...", I found out that format_str.size() == 1 which does not make sense.

[summivox]

Update: fmt::compile failed at runtime, with similar error.
I think the root cause might lie within how the string literal is massaged.

0x40086b3e: panic_abort at /home/summivox/lib/esp-idf/components/esp_system/panic.c:367

0x4008711d: esp_system_abort at /home/summivox/lib/esp-idf/components/esp_system/system_api.c:108

0x4008c8a6: abort at /home/summivox/lib/esp-idf/components/newlib/abort.c:46

0x400f8ab7: __cxxabiv1::__terminate(void (*)()) at /builds/idf/crosstool-NG/.build/xtensa-esp32-elf/src/gcc/libstdc++-v3/libsupc++/eh_terminate.cc:47

0x400f8afe: std::terminate() at /builds/idf/crosstool-NG/.build/xtensa-esp32-elf/src/gcc/libstdc++-v3/libsupc++/eh_terminate.cc:57

0x400e5bb3: fmt::v7::detail::assert_fail(char const*, int, char const*) at /home/summivox/.espressif/tools/xtensa-esp32-elf/esp-2020r3-8.4.0/xtensa-esp32-elf/xtensa-esp32-elf/include/c++/8.4.0/bits/basic_string.h:200

0x400e6974: fmt::v7::detail::error_handler::on_error(char const*) at /home/summivox/.espressif/tools/xtensa-esp32-elf/esp-2020r3-8.4.0/xtensa-esp32-elf/xtensa-esp32-elf/include/c++/8.4.0/bits/basic_string.h:200

0x400dbdf7: void fmt::v7::detail::compile_format_string<false, char, fmt::v7::detail::compiled_format_base<char const*, void>::compiled_format_base(fmt::v7::basic_string_view<char>)::{lambda(fmt::v7::detail::format_part<char> const&)#1}>(fmt::v7::basic_string_view<char>, fmt::v7::detail::compiled_format_base<char const*, void>::compiled_format_base(fmt::v7::basic_string_view<char>)::{lambda(fmt::v7::detail::format_part<char> const&)#1}) at /media/summivox/nautilus-data/proj/shift-watch-esp32/build/../components/fmtlib/fmt/include/fmt/compile.h:202
 (inlined by) ?? at /media/summivox/nautilus-data/proj/shift-watch-esp32/build/../components/fmtlib/fmt/include/fmt/format.h:3097
 (inlined by) ?? at /media/summivox/nautilus-data/proj/shift-watch-esp32/build/../components/fmtlib/fmt/include/fmt/format.h:3153
 (inlined by) void fmt::v7::detail::compile_format_string<false, char, fmt::v7::detail::compiled_format_base<char const*, void>::compiled_format_base(fmt::v7::basic_string_view<char>)::{lambda(fmt::v7::detail::format_part<char> const&)#1}>(fmt::v7::basic_string_view<char>, fmt::v7::detail::compiled_format_base<char const*, void>::compiled_format_base(fmt::v7::basic_string_view<char>)::{lambda(fmt::v7::detail::format_part<char> const&)#1}) at /media/summivox/nautilus-data/proj/shift-watch-esp32/build/../components/fmtlib/fmt/include/fmt/compile.h:217

[vitaut]

I'm not sure about this particular compiler but here's an example with gcc 8 it seems to be based on: https://godbolt.org/z/v1qvs8.

fmt::compile is deprecated and will be removed.

[vitaut]

From the error message it looks like you should compile with exceptions enabled.

[eos175]

Hello, how can i compile with esp-idf on esp32?

try adding fmtlib to components folder, thank!!

[vitaut]

Hello, how can i compile with esp-idf on esp32?

Unfortunately I am not familiar with these.