[feature request] Blacklisting functions

[ExpHP]

In lammps-sys I have a feature to enable use of system include paths to locate mpi.h. When this feature is disabled, I want to forbid use of functions which depend on the MPI types.

if cfg!(not(feature = "system-mpi")) {
    gen = gen.blacklist_type("([oOpP])?[mM][pP][iI].*");
}

However, one of the functions I am exposing has such a type in its signature, leading to a compile error (cannot find type MPI_Comm in this scope). It is too difficult to write a whitelist pattern that does not match this function, so my workaround has been to instead define an empty enum replacement type when the feature is not enabled. (as a result, my feature flag is, strictly speaking, not purely additive in terms of build artefacts.)

What would be far better is the ability to simply blacklist the function lammps_open.

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>_>

<_<

Incidentally, this functionality is already actually possible through the use of the blacklist_type function:

if cfg!(not(feature = "system-mpi")) {
    gen = gen.blacklist_type("([oOpP])?[mM][pP][iI].*");
    gen = gen.blacklist_type("lammps_open");  // this actually blacklists the function!
}

so we pretty much already have the implementation. 😛

[fitzgen]

Sounds reasonable to me.

[maxfurman]

It sounds like this is just a request to alias blacklist_type to blacklist_function?

[ExpHP]

Heh, when I said "we pretty much already have the implementation", I was joking. Honestly, I'd consider the fact that blacklist_type blacklists functions to be a bug!

...but I guess the best step forward does in fact look more or less like exactly what you said:

• Add a blacklist_function method which calls blacklist_type
  • (This seems better to me than the alternative of renaming blacklist_type to blacklist, because the intended use-case of blacklist_type is well-documented in the book and I wouldn't want to sully it)
• Document its use case of allowing one to refine the results grabbed by whitelist_function
• Open an bug about the fact that blacklist_function and blacklist_type both actually do each other's jobs. 😛

[waywardmonkeys]

I'm working on this.

[jhod0]

It looks like this is implemented: https://docs.rs/bindgen/0.44.0/bindgen/struct.Builder.html#method.blacklist_function

Should this issue be closed?

[emilio]

Yup, thanks! Fixed by #1364.