[Win64] Prebuilt 7.0.1 linkage errors.

[Pandoa]

[REQUIRED] Please fill in the following fields:

• Pre-built SDK from the website
• Firebase C++ SDK version: 7.0.1
• Problematic Firebase Component: App, Remote Config
• Other Firebase Components in use: Auth, Firestore
• Platform you are using the C++ SDK on: Windows x64-Release /MD vs2019
• Platform you are targeting: desktop

[REQUIRED] Please describe the issue here:

Impossible to build an app linked against the SDK with a linkage error if the following libraries are linked:

1. firebase_app.lib
2. firebase_remote_config.lib
3. firebase_firestore.lib
4. firebase_auth.lib

Exact linkage error:

1>firebase_app.lib(0865aae1211b26b3ccf22fd1b579e000_protobuf_nanopb_static.dir_Release_pb_decode.obj) : error LNK2005: f_b_pb_decode already defined in firebase_remote_config.lib(c80cae8cb6fc354c32078cec2fc51bbc_firebase_remote_config.dir_Release_pb_decode.obj)
1>firebase_app.lib(0865aae1211b26b3ccf22fd1b579e000_protobuf_nanopb_static.dir_Release_pb_decode.obj) : error LNK2005: f_b_pb_decode_noinit already defined in firebase_remote_config.lib(c80cae8cb6fc354c32078cec2fc51bbc_firebase_remote_config.dir_Release_pb_decode.obj)
1>firebase_app.lib(0865aae1211b26b3ccf22fd1b579e000_protobuf_nanopb_static.dir_Release_pb_decode.obj) : error LNK2005: f_b_pb_decode_delimited already defined in firebase_remote_config.lib(c80cae8cb6fc354c32078cec2fc51bbc_firebase_remote_config.dir_Release_pb_decode.obj)
...
fatal error LNK1169: one or more multiply defined symbols found.

Steps to reproduce:

1. Download the Firebase C++ SDK version 7.0.1.
2. Create a new blank Visual Studio project.
3. Compile the Relevant Code provided below.

Have you been able to reproduce this issue with just the Firebase C++ quickstarts ? Yes
Issue repro rate: 100%

Project to reproduce:
firebase_project_reproduction.zip
(relevant SDK libs and headers included).

Output:

firebase_app.lib: XXX already defined in firebase_remote_config.lib
...
fatal error LNK1169: one or more multiply defined symbols found.

Relevant Code:

#pragma comment(lib, "firebase_app.lib")
#pragma comment(lib, "firebase_remote_config.lib")
#pragma comment(lib, "firebase_firestore.lib")
#pragma comment(lib, "firebase_auth.lib")

#include "firebase/remote_config.h"
#include "firebase/firestore/query.h"

int main()
{
	firebase::firestore::Query Query;
}

[jonsimantov]

Thanks for letting us know about this issue. A fix (#275) has been merged into our development branch and will be included in the next binary SDK release.