rt_round redefinition problem

Hi everyone,

I'm using Matlab 2020a with Autosar platform. When I try to generate Autosar code for MPC series microcontroller, it always generates rt_roundd function and its extern. There is an error here, in the same C file, the function declaration is made with extern and the body of this function is in the same file. Then I try to compile the whole project, I get the redefinition error and I can't get past the linking phase. Below you can see the contents written in the C file.

extern real_T rt_roundd(real_T u);

// real_T rt_roundd(real_T u)
// {
  // real_T y;
  // if (fabs(u) < 4.503599627370496E+15) {
    // if (u >= 0.5) {
      // y = floor(u + 0.5);
    // } else if (u > -0.5) {
      // y = 0.0;
    // } else {
      // y = ceil(u - 0.5);
    // }
  // } else {
    // y = u;
  // }

  // return y;
// }

Answer 1

[Mrutyunjaya Hiremath]

It seems like you are encountering a conflict with the `rt_roundd` function in your MATLAB code generation for the Autosar platform. The issue you described occurs because the function is declared as `extern` in one place and defined in the same file. This can cause a redefinition error during the linking phase of compilation.

To resolve this issue, you can try the following steps:

1. Check MATLAB Code Generation Options: In MATLAB, go to the "Code Generation" settings and ensure that the "Code interface packaging" option is set to "Nonreusable function." This should prevent the generation of the `rt_roundd` function as an `extern` in the generated code.
2. Avoid Using Built-in Functions: If you have any custom code that uses the `rt_roundd` function, consider renaming that function to avoid conflicts with the built-in `rt_roundd` function in the generated code.
3. Rename Conflicting Function: If you don't have control over the MATLAB-generated code, you can rename the conflicting `rt_roundd` function in your C code manually. For example, you can rename it to something like `my_rt_roundd` in both the function declaration and the function definition.
4. Separate Declaration and Definition: If the function definition is provided separately from the declaration in the generated C code, you can modify the code to keep the declaration `extern` and place the function definition in a separate source file. This way, you won't have a redefinition conflict.
5. Check for Code Generation Issues: Ensure that your MATLAB code is written correctly and doesn't contain any issues that might lead to conflicts in the generated C code.