#1150057 rust-test-fork-macros: FTBFS: error[E0308]: mismatched types

#1150057#5
Date:
2026-10-05 12:40:15 UTC
From:
To:
Dear maintainer:

During a rebuild of all packages in unstable, this package failed to build.

Below you will find the last part of the build log (probably the most
relevant part, but not necessarily). If required, the full build log
is available here:

https://people.debian.org/~sanvila/build-logs/202610/

About the archive rebuild: The build was made on virtual machines from AWS,
using sbuild and a reduced chroot with only build-essential packages.

If you cannot reproduce the bug please contact me privately, as I
am willing to provide ssh access to a virtual machine where the bug is
fully reproducible.

If this is really a bug in one of the build-depends, please use
reassign and add an affects on src:rust-test-fork-macros, so that this is still
visible in the BTS web page for this package.

Thanks.
--------------------------------------------------------------------------------
[...]
help: consider wrapping the function in a closure
   |
46 |         .unwrap_or_else(|arg0: syn::error::Error| syn::Error::into_compile_error(/* syn::Error */))
   |                         +++++++++++++++++++++++++                               ++++++++++++++++++

error[E0308]: mismatched types
   --> src/lib.rs:119:27
    |
119 |     try_fork(attr.into(), input_fn, supports_bench)
    |     --------              ^^^^^^^^ expected `syn::item::ItemFn`, found `ItemFn`
    |     |
    |     arguments to this function are incorrect
    |
note: there are multiple different versions of crate `syn` in the dependency graph
   --> /<<PKGBUILDDIR>>/debian/cargo_registry/syn-3.0.6/src/macros.rs:36:22
    |
 36 |           $(#[$attr])* $pub $struct $name $body
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^ this is the expected type
    |
   ::: /<<PKGBUILDDIR>>/debian/cargo_registry/syn-2.0.119/src/macros.rs:36:22
    |
 36 |           $(#[$attr])* $pub $struct $name $body
    |                        ------------------------ this is the found type
    |
   ::: /<<PKGBUILDDIR>>/debian/cargo_registry/syn-3.0.6/src/item.rs:173:1
    |
173 | / ast_struct! {
174 | |     /// A free-standing function: `fn process(n: usize) -> Result<()> { ... }`.
175 | |     #[cfg_attr(docsrs, doc(cfg(feature = "full")))]
176 | |     pub struct ItemFn {
...   |
184 | | }
    | |_- in this macro invocation
    = help: you can use `cargo tree` to explore your dependency tree
note: function defined here
   --> /<<PKGBUILDDIR>>/debian/cargo_registry/test-fork-core-0.1.5/src/procmac.rs:295:8
    |
295 | pub fn try_fork(attr: Tokens, input_fn: ItemFn, supports_bench: bool) -> Result<Tokens> {
    |        ^^^^^^^^
    = note: this error originates in the macro `ast_struct` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0631]: type mismatch in function arguments
   --> src/lib.rs:120:25
    |
120 |         .unwrap_or_else(syn::Error::into_compile_error)
    |          -------------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |          |              |
    |          |              expected due to this
    |          |              found signature defined here
    |          required by a bound introduced by this call
    |
    = note: expected function signature `fn(syn::error::Error) -> _`
               found function signature `fn(syn::Error) -> _`
note: required by a bound in `Result::<T, E>::unwrap_or_else`
   --> /usr/src/rustc-1.96.1/library/core/src/result.rs:1616:4
help: consider wrapping the function in a closure
    |
120 |         .unwrap_or_else(|arg0: syn::error::Error| syn::Error::into_compile_error(/* syn::Error */))
    |                         +++++++++++++++++++++++++                               ++++++++++++++++++

Some errors have detailed explanations: E0308, E0631.
For more information about an error, try `rustc --explain E0308`.
error: could not compile `test-fork-macros` (lib) due to 4 previous errors

Caused by:
  process didn't exit successfully: `CARGO=/usr/bin/cargo CARGO_CRATE_NAME=test_fork_macros CARGO_MANIFEST_DIR=/<<PKGBUILDDIR>> CARGO_MANIFEST_PATH=/<<PKGBUILDDIR>>/Cargo.toml CARGO_PKG_AUTHORS='Daniel Mueller <deso@posteo.net>' CARGO_PKG_DESCRIPTION='Supporting procedural macro crate for test-fork.
  ' CARGO_PKG_HOMEPAGE='https://github.com/d-e-s-o/test-fork [too-long-redacted] rn proc_macro` (exit status: 1)
warning: build failed, waiting for other jobs to finish...
error: could not compile `test-fork-macros` (lib test) due to 4 previous errors

Caused by:
  process didn't exit successfully: `CARGO=/usr/bin/cargo CARGO_CRATE_NAME=test_fork_macros CARGO_MANIFEST_DIR=/<<PKGBUILDDIR>> CARGO_MANIFEST_PATH=/<<PKGBUILDDIR>>/Cargo.toml CARGO_PKG_AUTHORS='Daniel Mueller <deso@posteo.net>' CARGO_PKG_DESCRIPTION='Supporting procedural macro crate for test-fork.
  ' CARGO_PKG_HOMEPAGE='https://github.com/d-e-s-o/test-fork [too-long-redacted] rn proc_macro` (exit status: 1)
dh_auto_test: error: /usr/share/cargo/bin/cargo test --all returned exit code 101
make[1]: *** [debian/rules:6: override_dh_auto_test] Error 25
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:3: binary] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2
--------------------------------------------------------------------------------

#1150057#10
Date:
2026-10-06 00:34:38 UTC
From:
To:
We believe that the bug you reported is fixed in the latest version of
rust-test-fork-macros, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1150057@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Peter Michael Green <plugwash@debian.org> (supplier of updated rust-test-fork-macros package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Tue, 06 Oct 2026 00:03:08 +0000
Source: rust-test-fork-macros
Architecture: source
Version: 0.1.6-1
Distribution: unstable
Urgency: medium
Maintainer: Debian Rust Maintainers <pkg-rust-maintainers@alioth-lists.debian.net>
Changed-By: Peter Michael Green <plugwash@debian.org>
Closes: 1150057
Changes:
 rust-test-fork-macros (0.1.6-1) unstable; urgency=medium
 .
   * Team upload.
   * Package test-fork-macros 0.1.6 from crates.io using debcargo 2.8.4
     + New upstream uses syn 3 (closes: #1150057)
Checksums-Sha1:
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Checksums-Sha256:
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Files:
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