Fix -Wrestrict in vtkFSSurfaceAnnotationReader

[jcfr]

/tmp/SlicerFreeSurfer/FreeSurfer/vtkFSSurfaceAnnotationReader.cxx: In member function ‘int vtkFSSurfaceAnnotationReader::ReadFSAnnotation()’:
/tmp/SlicerFreeSurfer/FreeSurfer/vtkFSSurfaceAnnotationReader.cxx:353:26: warning: passing argument 1 to restrict-qualified parameter aliases with argument 3 [-Wrestrict]
  353 |           sprintf (this->NamesList, "%s%3d {%s} ", this->NamesList,
      |                    ~~~~~~^~~~~~~~~  

If copying takes place between objects that overlap as a result of a call to sprintf() or snprintf(), the results are undefined.

Source: https://stackoverflow.com/a/1973595/1539918

And answer from ChatGPT:

This warning suggests that there is a potential issue with the use of the restrict keyword in the function argument, and it is causing an aliasing problem.

The restrict keyword is a C99 feature that tells the compiler that a particular pointer argument is not aliased by any other pointer in the same scope. In other words, if you use the restrict keyword, you're telling the compiler that the pointer passed as an argument does not point to the same memory location as any other pointer passed to the same function.

In your case, passing this->NamesList as the first argument to sprintf with %s format specifier is causing the warning. The %s format specifier expects a null-terminated string, and since the sprintf function can write to the memory location pointed to by this->NamesList, it is possible that it can also write to memory locations pointed to by other pointers. This violates the restrict keyword, which is meant to prevent such aliasing.

To fix this warning, you should consider using a different approach to write to this->NamesList. You can either remove the restrict keyword from the function argument, or you can use a temporary buffer to store the formatted string and then copy it to this->NamesList using strcpy or strncpy. Here is an example of the second approach:

char tempBuffer[256]; // temporary buffer to store the formatted string
sprintf(tempBuffer, "%s%3d {%s} ", this->NamesList, someNumber, someString);
strncpy(this->NamesList, tempBuffer, sizeof(this->NamesList));
this->NamesList[sizeof(this->NamesList)-1] = '\0'; // make sure the string is null-terminated

In this example, we use sprintf to format the string into tempBuffer, and then we use strncpy to copy the formatted string to this->NamesList. We also make sure that the string is null-terminated by setting the last character to '\0'. This approach avoids the aliasing issue and should fix the warning.

[lassoan]

This freesurfer file reader is all very old, low quality code. We just moved it out of Slicer core but did not review or rework it. If we touch it then we should modernize it a bit to use STL strings and streams.