VS2017 - Un explained linker error LNK2019 with usage of std::regex

Question

VS2017 - Un explained linker error LNK2019 with usage of std::regex

Hadimani, Basavaraj 1

Hello, I have a project where in I use std::regex to perform a check whether the given string matches the expression that I have set upfront. No issues what so ever. It builds, runs perfectly fine on VS2017 , professional version without any hazzles. I use the same code on on another project (my unit tests' project) and it throws up the following linker errors.

LNK2019: unresolved external symbol "public: static class std::locale::_Locimp * __cdecl std::locale::_Init(bool)" (?_Init@locale@std@@SAPAV_Locimp@12@_N@Z) referenced in function "public: __thiscall std::locale::locale(void)" (??0locale@std@@QAE@XZ)

LNK2019: unresolved external symbol "public: static class std::locale::_Locimp * __cdecl std::locale::_Getgloballocale(void)" (?_Getgloballocale@locale@std@@SAPAV_Locimp@12@XZ) referenced in function "public: class std::locale::facet const * __thiscall std::locale::_Getfacet(unsigned int)const " (?_Getfacet@locale@std@@QBEPBVfacet@12@I@Z) I have spent more than a day to understand the difference between the two projects (specifically the Properties-.Linker->Input->Additional Dependencies.. I dont find anything that explains the issue mentioned. I am unable to resolve the linker error as the mentioned internal methods are not used by me at all. Please help in resolving the same. Thanks in advance.

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Viorel 127.3K Reputation points

2021-03-09T18:08:05.863+00:00

What kind (framework) of Unit Tests are you using?

If possible, you can share a sample solution that demonstrate the problem.
Hadimani, Basavaraj 1 Reputation point

2021-03-09T18:22:40.447+00:00

Its an inhouse developed .. very simple and very similar to the Visual Studio CppUnitTestFramework.
As I said.. I use the following statements to include and forward declare the name space.

include <regex>

using namespace std;

And then.. using the following code for the regular expression matching!!

// Regular expression definition
std::regex pattern("(\w+)(\.|_)?(\w*)@(\w+)(\.(\w+))+");

std::string stdEmail;
CWString::copy(stdEmail, email);

// Match the e-mail string with regular expression pattern.
return regex_match(stdEmail, pattern);

This code compiles and runs in one of the regular project whereas, throws-up the linker error in my unit test project. I can share the project settings if you want to take a look. Thank you.
Viorel 127.3K Reputation points

2021-03-10T09:05:29.343+00:00

If possible, you can publish (on OneDrive, etc.) a full simple project that reproduces the problem.

2 answers

Viorel 127.3K Reputation points

2021-03-09T18:08:05.863+00:00

What kind (framework) of Unit Tests are you using?

If possible, you can share a sample solution that demonstrate the problem.
Hadimani, Basavaraj 1 Reputation point

2021-03-09T18:22:40.447+00:00

Its an inhouse developed .. very simple and very similar to the Visual Studio CppUnitTestFramework.
As I said.. I use the following statements to include and forward declare the name space.

include <regex>

using namespace std;

And then.. using the following code for the regular expression matching!!

// Regular expression definition
std::regex pattern("(\w+)(\.|_)?(\w*)@(\w+)(\.(\w+))+");

std::string stdEmail;
CWString::copy(stdEmail, email);

// Match the e-mail string with regular expression pattern.
return regex_match(stdEmail, pattern);

This code compiles and runs in one of the regular project whereas, throws-up the linker error in my unit test project. I can share the project settings if you want to take a look. Thank you.
Viorel 127.3K Reputation points

2021-03-10T09:05:29.343+00:00

If possible, you can publish (on OneDrive, etc.) a full simple project that reproduces the problem.

Answer 1

I get this error in my unit test code because i override "private" and "protected" keywords:

#if defined(UNIT_TEST)
#define protected public
#define private public
#endif

Of course, all my code compile, but the problem raized in link time, because std is precompiled using private and protected keywords, but linker searchs for public implementations:

public: static class std::locale::_Locimp * __cdecl std::locale::_Getgloballocale(void)" (?_Getgloballocale@locale@std@@SAPAV_Locimp@12@XZ)

Correct name found in stdlib:

private: static class std::locale::_Locimp * __cdecl std::locale::_Getgloballocale(void)" (?_Getgloballocale@locale@std@@SAPAV_Locimp@12@XZ)

The only difference is private -> public

SOLUTION: just remove #define's before include iostream and fstream

iostream

#if defined(UNIT_TEST)
#	undef private
#	undef protected
#endif

#include <iostream>
#include <fstream>

Answer 2

Hi HadimaniBasavaraj,

Please check if the VC++ directories of your test project is same with your project.

Best Regards, Dylan

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VS2017 - Un explained linker error LNK2019 with usage of std::regex

include <regex>

2 answers

Best Regards, Dylan