Panic when matching a Option<&str> and returning a String

[pedroldk]

Code

#![feature(proc_macro_hygiene, decl_macro)]

#[macro_use]
extern crate rocket;

#[get("/")]
fn index() -> String {
    format!("{:?}", routes![index])
}

#[get("/name")]
fn name() -> String {
    let x = &routes![name][0];
    match x.name {
        Some(y) => y.to_string(),
        None => "None".to_string(),
    }
}

fn main() {
    rocket::ignite().mount("/", routes![index, name]).launch();
}

Meta

rustc --version --verbose:

rustc 1.53.0-nightly (392ba2ba1 2021-04-17)
binary: rustc
commit-hash: 392ba2ba1a7d6c542d2459fb8133bebf62a4a423
commit-date: 2021-04-17
host: x86_64-pc-windows-msvc
release: 1.53.0-nightly
LLVM version: 12.0.0

Error output

Running `rustc --crate-name weatherrs --edition=2018 src\main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 -C metadata=20594bb75e20956b --out-dir C:\Users\pedro\Projects\weatherrs\target\debug\deps -C incremental=C:\Users\pedro\Projects\weatherrs\target\debug\incremental -L dependency=C:\Users\pedro\Projects\weatherrs\target\debug\deps --extern rocket=C:\Users\pedro\Projects\weatherrs\target\debug\deps\librocket-24c64ea9176bc371.rlib`
thread 'rustc' panicked at 'assertion failed: `(left == right)`
  left: `Some(Fingerprint(16035130432922222196, 6395012579070391062))`,
 right: `Some(Fingerprint(11764750703836629372, 13843522135975677865))`: found unstable fingerprints for predicates_of(core[d23b]::convert::From): GenericPredicates { parent: None, predicates: [(Binder(TraitPredicate(<Self as std::marker::Sized>), []), C:\Users\pedro\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\convert\mod.rs:365:20: 365:25 (#0)), (Binder(TraitPredicate(<T as std::marker::Sized>), []), C:\Users\pedro\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\convert\mod.rs:365:16: 365:17 (#0)), (Binder(TraitPredicate(<Self as std::convert::From<T>>), []), C:\Users\pedro\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib/rustlib/src/rust\library\core\src\convert\mod.rs:365:1: 365:25 (#0))] }', /rustc/392ba2ba1a7d6c542d2459fb8133bebf62a4a423\compiler\rustc_query_system\src\query\plumbing.rs:593:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

note: 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: rustc 1.53.0-nightly (392ba2ba1 2021-04-17) running on x86_64-pc-windows-msvc

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

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

query stack during panic:
#0 [predicates_of] computing predicates of `std::convert::From`
#1 [typeck] type-checking `index`
end of query stack
error: could not compile `weatherrs`

Caused by:
  process didn't exit successfully: `rustc --crate-name weatherrs --edition=2018 src\main.rs --error-format=json --json=diagnostic-rendered-ansi --crate-type bin --emit=dep-info,link -C embed-bitcode=no -C debuginfo=2 -C metadata=20594bb75e20956b --out-dir C:\Users\pedro\Projects\weatherrs\target\debug\deps -C incremental=C:\Users\pedro\Projects\weatherrs\target\debug\incremental -L dependency=C:\Users\pedro\Projects\weatherrs\target\debug\deps --extern rocket=C:\Users\pedro\Projects\weatherrs\target\debug\deps\librocket-24c64ea9176bc371.rlib` (exit code: 101)

Backtrace

query stack during panic:
#0 [predicates_of] computing predicates of `std::convert::From`
#1 [typeck] type-checking `index`
#2 [typeck_item_bodies] type-checking all item bodies
#3 [analysis] running analysis passes on this crate
end of query stack

[Aaron1011]

Duplicate of #84341. This is fixed in the latest nightly