How to add .lib files in visual studio code with gcc compiler toolchain

[meghnaembd]

We are facing an undefined reference to 'xxxxx' , this function definition is in a pre-compiled library which is of the type .lib,
We wanted to know how to add this .lib file in Visual Studio code, to build the file successfully.
This is the code that I have written in the tasks.json file to link the .lib file.
"version": "2.0.0",
"tasks": [
{
"label": "Linker",
"type": "shell",
"command": "g++",
"args": [
"${workspaceFolder}\main.o",
"-o",
"-LC:\nRF5_SDK_17.1.0_ddde560\examples\peripheral\spi\APP\sensor\lib\986algo.lib",
"-lmingw32",
"-lSDL2main",
"-lSDL2"
]
I would be grateful if anyone could help me resolve this issue. Thanks in advance

[theReynald]

Hi @meghnaembd.

The error message "undefined reference" is a linker error indicating that the function implementation, though declared, wasn't found during the linking phase.

To resolve the issue, you should ensure that:

1. Your .lib file actually contains the missing definition. Not all .lib files will necessarily be compatible with the GCC toolchain, especially if they were built using a different tool like MSVC.
2. The library is properly linked during the build.

From the provided tasks.json, here are some points to consider:

1. Use Forward Slashes:

   Even on Windows, when specifying paths in GCC or G++, it's often better to use forward slashes (/) rather than backslashes (\).

2. Library Paths and Library Flags:

   The -L flag is used to specify a directory where the linker should look for libraries. The -l flag is used to specify the library name. However, in your command, you're giving the full path of the library after -L, which isn't correct.

   If your library is named 986algo.lib and it's located in the path C:/nRF5_SDK_17.1.0_ddde560/examples/peripheral/spi/APP/sensor/lib/, the correct way to link it would be:

   "-LC:/nRF5_SDK_17.1.0_ddde560/examples/peripheral/spi/APP/sensor/lib/",
   "-l986algo"

   However, the GCC linker expects libraries to follow the lib[name].a naming pattern for static libraries. If 986algo.lib is a valid static library for GCC, you might need to rename it to lib986algo.a for it to be correctly recognized by the -l flag. If renaming is not an option, you can try specifying the full path to the .lib file in the linking command.

3. Is the Library Compatible?:

   If the .lib file was created with a different compiler (like MSVC), it might not be compatible with GCC's g++. In such cases, you'd either need to obtain a version of the library compatible with GCC or use the same toolchain that was used to create the .lib file.

4. Check the Library's Contents:

   You can use the nm tool (if available in your setup) to inspect the contents of the .lib (or .a) file to ensure that the desired symbols are indeed present:

   nm path_to_lib_file.lib | grep symbol_name
   

5. Dependency Order:

   Sometimes the order of libraries and objects matters during linking. Ensure that all your object files and libraries are in the correct order.

6. Toolchain Mismatch:

   Are you sure that mingw32, SDL2main, and SDL2 are necessary and compatible with your .lib file and your main object file? Sometimes, mixing libraries from different toolchains or versions can lead to linkage problems.

Finally, consider checking the output logs carefully. They might contain additional details about what's causing the linkage error. If the above solutions don't resolve the issue, it might be beneficial to provide more detailed information about your project setup, how the .lib file was generated, and the complete error message(s) you're encountering.

[corpvs2]

First, generate the .o file by modifying the task json configuration "command " "args" as follows:
“-fdiagnostics-color=always”,
“-c”, “${file}”,
“-o”,
“${fileDirname}${fileBasenameNoExtension}.o”

The CMD is: gcc -c sqlite3.c

Next, generate the lib file by changing the command in the .task to
“C:\MinGW\bin\ar.exe”,

“-cr” ,
“${fileDirname}${fileBasenameNoExtension}.lib” ,
“${fileDirname}${fileBasenameNoExtension}.o”

The CMD is: ar.exe cr sqlite3.lib sqlite3.o

Finally, link using “C:\MinGW\bin\gcc.exe”
“-fdiagnostics-color=always”,
“-g”,
“${file}”,
“-I${fileDirname}”,
“-L${fileDirname}”,
“-lhello” ,
“-o”,
“${fileDirname}${fileBasenameNoExtension}.exe” ,
“-static”

The CMD is: gcc DBmanger.c -o DBmanger.exe -lsqlite3 -I. -L.

[Karliz24]

🙃

[Karliz24]

We are facing an undefined reference to 'xxxxx' , this function definition is in a pre-compiled library which is of the type .lib,

We wanted to know how to add this .lib file in Visual Studio code, to build the file successfully.

This is the code that I have written in the tasks.json file to link the .lib file.

"version": "2.0.0",

"tasks": [

    {

        "label": "Linker",

        "type": "shell",

        "command": "g++",

        "args": [

            "${workspaceFolder}\\main.o",

            "-o",

            "-LC:\\nRF5_SDK_17.1.0_ddde560\\examples\\peripheral\\spi\\APP\\sensor\\lib\\986algo.lib",

            "-lmingw32",

            "-lSDL2main",

            "-lSDL2"

        ]

I would be grateful if anyone could help me resolve this issue. Thanks in advance