new clang-sys packages break against older versions

[iximeow]

hi, sorry for the bad news! this applies both to the 0.29 and 0.28 packages, in slightly different ways:

in 0.28.1, CXCursorAndRangeVisitor's visit was extern "C" fn(_: *mut c_void, _: CXCursor, _: CXSourceRange) -> CXVisitorResult, but in 0.28.2 that field turned into Option<extern "C" fn(*mut c_void, CXCursor, CXSourceRange) -> i32>. since Cargo expects patch bumps of 0.y.z versions to be compatible, this makes for breaking crate selections when building f.ex clang.

in 0.29.3, CXCursorAndRangeVisitor's visit was Option<extern "C" fn(_: *mut c_void, _: CXCursor, _: CXSourceRange) -> CXVisitorResult> but became Option<extern "C" fn(*mut c_void, CXCursor, CXSourceRange) -> i32> in 0.29.4. The same breaking version selection issues apply here.

This showed up in at least two places - pgcentralfoundation/pgrx#8 (comment) this issue, and an entirely unrelated build issue I was just tracking down :)

edit: for good measure I checked 0.27 as well - 0.27.0 -> 0.27.1 has the same breaking change as in 0.28.1 -> 0.28.2

[iximeow]

ah, I see this relates to #96 - a quick read has me suspecting that this means clang-sys-linkage is not as API-compatible as was discussed there?

[jrandall]

We've been bitten by this as well - bindgen 0.52.0 fails to build as of this morning with a bunch of errors such as:

error[E0433]: failed to resolve: use of undeclared type or module `clang_Cursor_getMangling`                                                                                                                                                                                                                                                                                                                                            

It is building against v0.28.2 but it looks like bindgen requires an earlier version. It does look like this relates to #96, yes.

[lexxvir]

@jrandall Same here, see my issue in the bindgen repo rust-lang/rust-bindgen#1827

[KyleMayes]

The offending versions have been yanked, things should be back to the way they were.
Sorry for the trouble, I did not realize there were API incompatibilities between v0.27 and v0.28.
I guess that's what I get for trying to solve people's build problems, just cause a bunch more... 🤷‍♂️