Undefined reference to functions of regex.h library (IDFGH-372)

[gost-serb]

Environment

• Development Kit: ESP32-DevKitC
• Kit version: v2
• Core (if using chip or module): ESP-WROOM32
• IDF version: master 31c14a5
• Development Env: Make
• Operating System: Ubuntu
• Power Supply: USB

Problem Description

When building a project with C regex (#include <regex.h>) linker reports about undefined reference of regcomp/regexec functions

Expected Behavior

Project builds successfully.

Actual Behavior

Failed on linkage phase

Code to reproduce this issue

#include <regex.h>

void app_main()
{
    regex_t regex;
   
    regcomp(&regex, "^a[[:alnum:]]", 0);
}

Debug Logs

/home/esp/foo/build/main/libmain.a(main.o):(.literal.app_main+0x14): undefined reference to `regcomp'
/home/esp/foo/build/main/libmain.a(main.o): In function `app_main':
/home/esp/foo/main/main.c:388: undefined reference to `regcomp'
collect2: error: ld returned 1 exit status

[negativekelvin]

I believe the supplied newlib does not provide regex support but you can use std::regex from libstdc++

[gost-serb]

But if I use only C language there are no standard regex library?

[HrMitrev]

Has anyone found any altrnative to POSIX's regex? I'm contemplating on using https://github.com/kokke/tiny-regex-c, but it lacks some features. Is there any way to add the source code to esp-idf in order to make /components/newlib/include/regex.h work?

[moefear85]

bump. unless c++ regex is supported, then unbump.