bindgen 0.71 introduces regression referencing proc_macro2::Literal::c_string

[yrp604]

When updating a crate of mine to bindgen 0.71, I started receiving this error:

C:\Users\x\OneDrive\Documents\bad64\bad64-sys>cargo check
    Updating crates.io index
     Locking 2 packages to latest compatible versions
    Updating bindgen v0.70.1 -> v0.71.1
    Updating rustc-hash v1.1.0 -> v2.1.1
   Compiling proc-macro2 v1.0.69
   Compiling clang-sys v1.8.1
   Compiling bindgen v0.71.1
   Compiling rustc-hash v2.1.1
   Compiling quote v1.0.33
   Compiling syn v2.0.39
   Compiling prettyplease v0.2.15
error[E0599]: no function or associated item named `c_string` found for struct `proc_macro2::Literal` in the current scope
    --> C:\Users\x\.cargo\registry\src\index.crates.io-1949cf8c6b5b557f\bindgen-0.71.1\codegen\mod.rs:734:62
     |
734  | ...                   let cstr = proc_macro2::Literal::c_string(cstr);
     |                                                        ^^^^^^^^ function or associated item not found in `Literal`
     |
note: if you're trying to build a new `proc_macro2::Literal` consider using one of the following associated functions:
      proc_macro2::Literal::u8_suffixed
      proc_macro2::Literal::u16_suffixed
      proc_macro2::Literal::u32_suffixed
      proc_macro2::Literal::u64_suffixed
      and 28 others
    --> C:\Users\x\.cargo\registry\src\index.crates.io-1949cf8c6b5b557f\proc-macro2-1.0.69\src\lib.rs:1097:5
     |
1097 | /     suffixed_int_literals! {
1098 | |         u8_suffixed => u8,
1099 | |         u16_suffixed => u16,
1100 | |         u32_suffixed => u32,
...    |
1109 | |         isize_suffixed => isize,
1110 | |     }
     | |_____^
     = note: this error originates in the macro `suffixed_int_literals` (in Nightly builds, run with -Z macro-backtrace for more info)
help: there is an associated function `string` with a similar name
     |
734  -                             let cstr = proc_macro2::Literal::c_string(cstr);
734  +                             let cstr = proc_macro2::Literal::string(cstr);
     |

For more information about this error, try `rustc --explain E0599`.
error: could not compile `bindgen` (lib) due to 1 previous error

This does not occur with bindgen 0.70.

I've pushed the relevant repro branch here: https://github.com/yrp604/bad64-sys/tree/bindgen-repro, and it should repro with cargo check. This repros on both Windows and Linux, nightly and stable.

[yrp604]

This has stopped reproducing on my machine after reporting this.... I am very confused as to how or why, but apologies for the noise.

[schmitch]

actually I have exactly the same problem, after updaing a dependency which updates bindgen to 0.7 hm

[AzHicham]

Hello I have the same exact issue on Ubuntu 22.04 & Macos 14.
On a Renovate deps update bindgen 0.70 -> 0.71

https://github.com/AzHicham/openslide-sys/actions/runs/13652045388/job/38162635083?pr=96#step:6:71

[Fireronin]

I also have this issue, on ubuntu with rust nightly 1.87

[wentasah]

This was fixed by #3048, which was merged just after 0.71.1 release. In my project, the problem disappeared after running cargo update proc-macro2 --precise 1.0.80.

[MarijnS95]

Would it make sense to add a cargo +nightly -Zminimal-versions generate-lockfile step to the CI to prevent similar mistakes in the future? This fix still hasn't made it into a subsequent (patch) release, requiring downstream crates that do check their minimum version bounds to manually make an exception and bump the proc-macro2 crate.