Including <iostream> gives misleading error

[mje-nz]

Basic Infos

• This issue complies with the issue POLICY doc.
• I have read the documentation at readthedocs and the issue is not addressed there.
• I have tested that the issue is present in current master branch (aka latest git).
• I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: N/A
• Core Version: c12c9e2
• Development Env: Arduino IDE
• Operating System: MacOS

Settings in IDE

• Module: Generic ESP8266 Module
• Flash Mode: qio
• Flash Size: 1MB
• lwip Variant: v2 Lower Memory
• Reset Method: ck
• Flash Frequency: 40Mhz
• CPU Frequency: 80Mhz
• Upload Using: serial
• Upload Speed: 115200

Problem Description

Compiling a sketch with #include <iostream> for ESP8266 gives a long, irrelevant error. Googling the error finds people who have their build system set up incorrectly, which doesn't help. I discovered this after accidentally leaving some debugging code in a hardware-agnostic utility class.

MCVE Sketch

#include <Arduino.h>
#include <iostream>

void setup() {}
void loop() {}

Compile error

Archiving built core (caching) in: /var/folders/9v/4bdlzlv544d3gn87rpg4kdd00000gn/T/arduino_cache_272822/core/core_esp8266_esp8266_generic_CpuFrequency_80,ResetMethod_ck,CrystalFreq_26,FlashFreq_40,FlashMode_qio,FlashSize_1M0,LwIPVariant_v2mss536,Debug_Disabled,DebugLevel_None____,UploadSpeed_115200_f268ef1bf7b434efe7be82ffaf83fd6d.a
arduino.ar(libc_replacements.c.o): In function `_putc_r':
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/cores/esp8266/libc_replacements.c:96: multiple definition of `_putc_r'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/libc/xtensa-lx106-elf/lib/libc.a(lib_a-putc.o):/Users/igrokhotkov/e/newlib-xtensa/xtensa-lx106-elf/newlib/libc/stdio/../../../.././newlib/libc/stdio/putc.c:97: first defined here
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(locale-inst.o):(.literal._ZSt9use_facetISt5ctypeIcEERKT_RKSt6locale[std::ctype<char> const& std::use_facet<std::ctype<char> >(std::locale const&)]+0x4): undefined reference to `std::__throw_bad_cast()'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(locale-inst.o): In function `std::ctype<char> const& std::use_facet<std::ctype<char> >(std::locale const&)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/locale_classes.tcc:114: undefined reference to `std::__throw_bad_cast()'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(locale-inst.o): In function `std::numpunct<char> const& std::use_facet<std::numpunct<char> >(std::locale const&)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/locale_classes.tcc:114: undefined reference to `std::__throw_bad_cast()'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(locale-inst.o): In function `std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > > const& std::use_facet<std::num_put<char, std::ostreambuf_iterator<char, std::char_traits<char> > > >(std::locale const&)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/locale_classes.tcc:114: undefined reference to `std::__throw_bad_cast()'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(locale-inst.o): In function `std::num_get<char, std::istreambuf_iterator<char, std::char_traits<char> > > const& std::use_facet<std::num_get<char, std::istreambuf_iterator<char, std::char_traits<char> > > >(std::locale const&)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/locale_classes.tcc:114: undefined reference to `std::__throw_bad_cast()'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(locale-inst.o):/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/locale_classes.tcc:114: more undefined references to `std::__throw_bad_cast()' follow
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(ios-inst.o):(.literal._ZNSt9basic_iosIcSt11char_traitsIcEE5clearESt12_Ios_Iostate[std::basic_ios<char, std::char_traits<char> >::clear(std::_Ios_Iostate)]+0x4): undefined reference to `std::__throw_ios_failure(char const*)'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(ios-inst.o): In function `std::basic_ios<char, std::char_traits<char> >::clear(std::_Ios_Iostate)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/basic_ios.tcc:122: undefined reference to `std::__throw_ios_failure(char const*)'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(ios-inst.o): In function `std::basic_ios<wchar_t, std::char_traits<wchar_t> >::clear(std::_Ios_Iostate)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/include/bits/basic_ios.tcc:122: undefined reference to `std::__throw_ios_failure(char const*)'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(c++locale.o):(.literal._ZNSt6locale5facet18_S_create_c_localeERPiPKcS1_+0x4): undefined reference to `std::__throw_runtime_error(char const*)'
/Users/Matthew/Library/Arduino15/packages/esp8266/hardware/esp8266/master/tools/sdk/lib/libstdc++.a(c++locale.o): In function `std::locale::facet::_S_create_c_locale(int*&, char const*, int*)':
/Users/igrokhotkov/e/ESPTools/crosstool-NG/.build/xtensa-lx106-elf/build/build-cc-gcc-final/xtensa-lx106-elf/libstdc++-v3/src/c++98/c++locale.cc:207: undefined reference to `std::__throw_runtime_error(char const*)'
collect2: error: ld returned 1 exit status
exit status 1
Error compiling for board Generic ESP8266 Module.

For comparison, here is the error when compiled for Arduino Uno:

/Users/Matthew/Documents/Arduino/sketch_apr21a/sketch_apr21a.ino:2:20: fatal error: iostream: No such file or directory
 #include <iostream>
                    ^
compilation terminated.
exit status 1
Error compiling for board Arduino/Genuino Uno.

[devyte]

The error you see is not irrelevant, it explains what happens: the linker can't find the implementation for exceptions (among other things), and that is because exceptions are currently not supported on the ESP. However, the iostream.h file is in fact present. On the Uno, it seems that the iostream.h header is not present.
AFAIK, stdlibc++ support is not complete here, and iostream is among the parts not supported. I could be wrong, of course.
@igrr is my previous statement correct?

[igrr]

Yes, you are right. I'll take a look re: missing symbols.

…

On Sun, Apr 22, 2018, 11:41 Develo ***@***.***> wrote: The error you see is not irrelevant, it explains what happens: the linker can't find the implementation for exceptions (among other things), and that is because exceptions are currently not supported on the ESP. However, the iostream.h file is in fact present. On the Uno, it seems that the iostream.h header is not present. AFAIK, stdlibc++ support is not complete here, and iostream is among the parts not supported. I could be wrong, of course. @igrr <https://github.com/igrr> is my previous statement correct? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#4663 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AEJceibwIa21kOdpd-FgFEBzojgA6F9Sks5tq_wCgaJpZM4TeSRe> .

[bestpika]

I got same error.

#include <iostream>
#include <string>
#include <regex>

void setup() {
  std::regex pattern("^GET ([^ ]+) HTTP.*$");
}

void loop() {

}

[shineangelic]

same here with version 2.4.1 on Arduino IDE 1.8.5

undefined reference to `std::__throw_bad_cast()'

with test sketch:

#include <sstream>
#include <Arduino.h>

std::stringstream s;

void setup()
{
    std::stringstream tester("");
    tester << "hello stream";
    Serial.begin(9600);
    Serial.println(tester.str().c_str());
}

void loop()
{

}

[shineangelic]

probably related/duplicate of #3358

[igrr]

As mentioned above, this is combination of #3358 and #4630. Should be fixed via #5047. Closing as duplicate, please follow these issue links and click "Subscribe" to receive further updates.