Simulink code generation: function stubs from Function Caller blocks and their return values/arguments

In my Simulink model I have several Function Caller blocks. The function prototypes are simply

y = someFunction()

The output arguments use custom enum types and are given as

someEnum(1)

The output signal is defined as one-dimensional throughout.

When generating code from the model, these Function Callers have always yielded a function stub in the expected form of

extern someEnum someFunction(void);

However, after a lot of changes recently, I've just noticed that code generation now yields function stubs in the form of

extern void someFunction(someEnum *rty_y);

for some (not all!) Function Caller blocks.

I have compared every parameter about the Function caller blocks and the related output signals that I could find but I can't find any difference between the affected ones and those working as expected in the current version or the same blocks in previous versions. All functions and signals have been renamed, but that's also true for those Function Caller blocks that are not affected.

The Code Generation options are also identical.

I have tried to understand from the help files what might cause the coder to use pointer arguments instead of direct return values for the function stubs but couldn't find anything.

Any hint at what might cause the code generator to use pointers would be greatly appreciated.

Answer 1

[Simon Ahrens]

Found the problem. Some of the affected blocks had their C/C++ return argument set to "void" in their "Configure C/C++ Function Interface" dialog.

Some of the affected blocks (unfortunately, both of those I had checked before as well) were still set to "y" here and I had to change the setting to "void" and back to "y" before it yielded the desired result.