c - Why is "typedef struct foo foo;" considered harmful?

Question

In typedef and struct namespaces in C vs C++, one of the comments seems to imply that exposing some struct foo is preferable to using typedef along the lines of...

typedef struct foo foo;

...and then using foo instead of struct foo throughout the API.

Are there any downsides to the latter variant?

Answer 1

The only downside(*) is that it hides the fact that foo is a struct, and not an alias for some builtin type.

Note(*): it's matter of taste whether this is a downside for you.

• It's good for total opaqueness (see the first comment below).
• To see why some people think this is a downside, check the linux kernel coding style (typedefs chapter).