ICE in derivable_impls: Patch span is beyond the end of buffer

[dtolnay]

Summary

This triggers an ICE as of nightly-2025-11-07:

// src/main.rs

#![warn(clippy::derivable_impls)]

#[macro_use]
mod macros;

my_enum!();

impl Default for Enum {
    fn default() -> Self {
        Enum::Variant
    }
}

fn main() {}

// src/macros.rs

macro_rules! my_enum {
    () => {
        pub enum Enum {
            Variant,
        }
    };
}

$ cargo clippy
thread 'rustc' (2243971) panicked at /rust/deps/annotate-snippets-0.12.8/src/renderer/source_map.rs:427:13:
Patch span `14..94` is beyond the end of buffer `14`
...

I was unsure whether to report this here or in rust-lang/rust but it bisects to rust-lang/rust#148188. In nightly-2025-11-06 and older there is no ICE.

warning: this `impl` can be derived
  --> src/main.rs:10:1
   |
10 | / impl Default for Enum {
11 | |     fn default() -> Self {
12 | |         Enum::Variant
13 | |     }
14 | | }
   | |_^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#derivable_impls
note: the lint level is defined here
  --> src/main.rs:3:9
   |
 3 | #![warn(clippy::derivable_impls)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^

Version

rustc 1.93.0-nightly (c90bcb957 2025-11-06)
binary: rustc
commit-hash: c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38
commit-date: 2025-11-06
host: x86_64-unknown-linux-gnu
release: 1.93.0-nightly
LLVM version: 21.1.3

Error output

Backtrace

thread 'rustc' (2243971) panicked at /rust/deps/annotate-snippets-0.12.8/src/renderer/source_map.rs:427:13:
Patch span `14..94` is beyond the end of buffer `14`
stack backtrace:
 0: __rustc::rust_begin_unwind
 1: core::panicking::panic_fmt
 2: annotate_snippets::renderer::render::render
 3: <rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitter>::emit_messages_default
 4: <rustc_errors::annotate_snippet_emitter_writer::AnnotateSnippetEmitter as rustc_errors::emitter::Emitter>::emit_diagnostic
 5: <rustc_errors::json::Diagnostic>::from_errors_diagnostic
 6: <rustc_errors::json::JsonEmitter as rustc_errors::emitter::Emitter>::emit_diagnostic
 7: <rustc_errors::DiagCtxtInner>::emit_diagnostic::{closure#3}
 8: rustc_interface::callbacks::track_diagnostic::<core::option::Option<rustc_span::ErrorGuaranteed>>
 9: <rustc_errors::DiagCtxtInner>::emit_diagnostic
10: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
11: <() as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
12: rustc_middle::lint::lint_level::lint_level_impl
13: clippy_lints::derivable_impls::check_enum
14: <clippy_lints::derivable_impls::DerivableImpls as rustc_lint::passes::LateLintPass>::check_item
15: <rustc_lint::late::LateContextAndPass<rustc_lint::late::RuntimeCombinedLateLintPass> as rustc_hir::intravisit::Visitor>::visit_nested_item
16: <rustc_lint::late::LateContextAndPass<rustc_lint::late::RuntimeCombinedLateLintPass>>::process_mod
17: rustc_lint::late::check_crate::{closure#0}
18: rustc_lint::late::check_crate
19: rustc_interface::passes::analysis
    [... omitted 1 frame ...]
20: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
21: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust-clippy/issues/new?template=ice.yml

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/git/repro/rustc-ice-2025-11-07T03_14_26-2243970.txt` to your bug report

note: compiler flags: --crate-type bin -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [analysis] running analysis passes on crate `repro`
end of query stack
note: Clippy version: clippy 0.1.93 (c90bcb9571 2025-11-06)

[Jarcho]

This looks like a rustc bug. This diagnostic in particular only uses spans from the HIR tree (shrink_to_lo is used for the suggestions, but that should always be a valid span).