ICE: Parser: Diagnostic "`box_syntax` has been removed" crashes if the source isn't available

[fmease]

Found by grepping through the compiler via rg 'span_to_snippet.+?(expect|unwrap)\(' compiler while reviewing an unrelated PR.

rust/compiler/rustc_parse/src/parser/expr.rs

Line 623 in 83734f2

let code = self.psess.source_map().span_to_snippet(inner_span).unwrap();

Reproducer

File a.rs:

#[macro_export]
macro_rules! make { () => { box 0 } }

File b.rs:

fn main() { let _ = a::make!(); }

1. Compile a: rustc a.rs --crate-type=lib.
2. Remove or move source file a.rs.
3. Compile b: rustc b.rs -L. --extern a --edition=2021.

Compiler Output

thread 'rustc' panicked at compiler/rustc_parse/src/parser/expr.rs:622:72:
called `Result::unwrap()` on an `Err` value: SourceNotAvailable { filename: Real(LocalPath("/home/fmease/programming/rust2/a.rs")) }

Full compiler output

thread 'rustc' panicked at compiler/rustc_parse/src/parser/expr.rs:622:72:
called `Result::unwrap()` on an `Err` value: SourceNotAvailable { filename: Real(LocalPath("/home/fmease/programming/rust2/a.rs")) }
stack backtrace:
   0:     0x7282e17fa055 - std::backtrace_rs::backtrace::libunwind::trace::h06bc9b86d9774048
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:116:5
   1:     0x7282e17fa055 - std::backtrace_rs::backtrace::trace_unsynchronized::hdda4e98324ad77bc
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7282e17fa055 - std::sys::backtrace::_print_fmt::h1f4c993ef7e831ac
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/sys/backtrace.rs:68:9
   3:     0x7282e17fa055 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h698f896ade9481b5
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/sys/backtrace.rs:41:26
   4:     0x7282e184af2b - core::fmt::rt::Argument::fmt::haa88e56ba5e1296a
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/core/src/fmt/rt.rs:173:76
   5:     0x7282e184af2b - core::fmt::write::h3d0682ae14ea41eb
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/core/src/fmt/mod.rs:1182:21
   6:     0x7282e17ee94f - std::io::Write::write_fmt::hc60fd9ed89ca5cb9
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/io/mod.rs:1827:15
   7:     0x7282e17fc8f1 - std::sys::backtrace::BacktraceLock::print::h5f66c3d07f69e011
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/sys/backtrace.rs:44:9
   8:     0x7282e17fc8f1 - std::panicking::default_hook::{{closure}}::h1a9e38caae8056a1
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/panicking.rs:269:22
   9:     0x7282e17fc5cc - std::panicking::default_hook::h7e7b66ab2d01b158
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/panicking.rs:296:9
  10:     0x7282ddc3c97a - std[aa7fdb062f64e277]::panicking::update_hook::<alloc[212cbeab23b2ab6c]::boxed::Box<rustc_driver_impl[248cc289afe8af4d]::install_ice_hook::{closure#0}>>::{closure#0}
  11:     0x7282e17fd2bf - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h29dbd1b8e444e7ae
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/alloc/src/boxed.rs:2165:9
  12:     0x7282e17fd2bf - std::panicking::rust_panic_with_hook::hd02d3e24e17903a0
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/panicking.rs:808:13
  13:     0x7282e17fcee7 - std::panicking::begin_panic_handler::{{closure}}::h7b7916e18a955842
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/panicking.rs:674:13
  14:     0x7282e17fa519 - std::sys::backtrace::__rust_end_short_backtrace::h95ffcaec96e3d90f
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/sys/backtrace.rs:172:18
  15:     0x7282e17fcb74 - rust_begin_unwind
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/panicking.rs:665:5
  16:     0x7282e18474f3 - core::panicking::panic_fmt::h167c2e689054226b
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/core/src/panicking.rs:74:14
  17:     0x7282e1847b46 - core::result::unwrap_failed::h1c25385300420846
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/core/src/result.rs:1679:5
  18:     0x7282de489606 - <rustc_parse[186c60b7585857b1]::parser::Parser>::collect_tokens_for_expr::<<rustc_parse[186c60b7585857b1]::parser::Parser>::parse_expr_prefix::{closure#8}>::{closure#0}
  19:     0x7282dfd39fcc - <rustc_parse[186c60b7585857b1]::parser::Parser>::parse_expr_prefix
  20:     0x7282db8ab6f1 - <rustc_parse[186c60b7585857b1]::parser::Parser>::parse_expr_assoc_with
  21:     0x7282df9673e0 - <rustc_expand[e0179ee32ba7c290]::mbe::macro_rules::ParserAnyMacro>::make
  22:     0x7282df96565d - <rustc_expand[e0179ee32ba7c290]::mbe::macro_rules::ParserAnyMacro as rustc_expand[e0179ee32ba7c290]::base::MacResult>::make_expr
  23:     0x7282db828e79 - <rustc_expand[e0179ee32ba7c290]::expand::MacroExpander>::fully_expand_fragment
  24:     0x7282dfc11ad8 - <rustc_expand[e0179ee32ba7c290]::expand::MacroExpander>::expand_crate
  25:     0x7282df561ff3 - rustc_interface[508d3ee0c578cb86]::passes::resolver_for_lowering_raw
  26:     0x7282df5615b1 - rustc_query_impl[769f4fcdd066b612]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[769f4fcdd066b612]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2}::{closure#0}, rustc_middle[8bb12d3a11dd28f7]::query::erase::Erased<[u8; 16usize]>>
  27:     0x7282df56159f - <rustc_query_impl[769f4fcdd066b612]::query_impl::resolver_for_lowering_raw::dynamic_query::{closure#2} as core[6449c673ca1a28dc]::ops::function::FnOnce<(rustc_middle[8bb12d3a11dd28f7]::ty::context::TyCtxt, ())>>::call_once
  28:     0x7282e003c79d - rustc_query_system[ca3d605384301f62]::query::plumbing::try_execute_query::<rustc_query_impl[769f4fcdd066b612]::DynamicConfig<rustc_query_system[ca3d605384301f62]::query::caches::SingleCache<rustc_middle[8bb12d3a11dd28f7]::query::erase::Erased<[u8; 16usize]>>, false, false, false>, rustc_query_impl[769f4fcdd066b612]::plumbing::QueryCtxt, false>
  29:     0x7282e003c437 - rustc_query_impl[769f4fcdd066b612]::query_impl::resolver_for_lowering_raw::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7282dff0bf63 - rustc_interface[508d3ee0c578cb86]::interface::run_compiler::<core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>, rustc_driver_impl[248cc289afe8af4d]::run_compiler::{closure#0}>::{closure#1}
  31:     0x7282dfee2849 - std[aa7fdb062f64e277]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[508d3ee0c578cb86]::util::run_in_thread_with_globals<rustc_interface[508d3ee0c578cb86]::util::run_in_thread_pool_with_globals<rustc_interface[508d3ee0c578cb86]::interface::run_compiler<core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>, rustc_driver_impl[248cc289afe8af4d]::run_compiler::{closure#0}>::{closure#1}, core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>>::{closure#0}, core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>>
  32:     0x7282dfee25fa - <<std[aa7fdb062f64e277]::thread::Builder>::spawn_unchecked_<rustc_interface[508d3ee0c578cb86]::util::run_in_thread_with_globals<rustc_interface[508d3ee0c578cb86]::util::run_in_thread_pool_with_globals<rustc_interface[508d3ee0c578cb86]::interface::run_compiler<core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>, rustc_driver_impl[248cc289afe8af4d]::run_compiler::{closure#0}>::{closure#1}, core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>>::{closure#0}, core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[6449c673ca1a28dc]::result::Result<(), rustc_span[e48981e571852391]::ErrorGuaranteed>>::{closure#1} as core[6449c673ca1a28dc]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  33:     0x7282e180720b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h009d53349cd0b13e
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/alloc/src/boxed.rs:2151:9
  34:     0x7282e180720b - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h497de5feb0301a41
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/alloc/src/boxed.rs:2151:9
  35:     0x7282e180720b - std::sys::pal::unix::thread::Thread::new::thread_start::hf327ce4ae0a5d31b
                               at /rustc/2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b/library/std/src/sys/pal/unix/thread.rs:108:17
  36:     0x7282e15a6ded - <unknown>
  37:     0x7282e162a0dc - <unknown>
  38:                0x0 - <unknown>

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

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

note: rustc 1.82.0-nightly (2cbbe8b8b 2024-07-28) running on x86_64-unknown-linux-gnu

query stack during panic:
#0 [resolver_for_lowering_raw] getting the resolver for lowering
end of query stack

Meta

rustc -Vv:

rustc 1.82.0-nightly (2cbbe8b8b 2024-07-28)
binary: rustc
commit-hash: 2cbbe8b8bb2be672b14cf741a2f0ec24a49f3f0b
commit-date: 2024-07-28
host: x86_64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 18.1.7

[fmease]

Solution: Get rid of span_to_snippet altogether and use a multi-part suggestion (Box::new(, )).