[DO NOT MERGE] crater proposed changes in unused must use lint #148577

WaffleLapkin · 2025-11-06T13:20:13Z

Based on #148214, easiest to review commit-by-commit.

This adds two lints:

unmustuse_in_always_ok checks for expressions of type Result<T, I> or ControlFlow<I, T> where
- I is uninhabited
- T is not a generic param
- T is not unit
- T does not have #[must_use] annotation
mustuse_in_always_ok checks for expressions of type Result<T, I> or ControlFlow<I, T> where
- I is uninhabited
- T is not a generic param
- T does have #[must_use] annotation (or is otherwise decided that it must be used)

The idea is to run crater with -D... such that we can detect where these cases occur.

…use lint (or more accurately `Result<T, Uninhabited>`/`ControlFlow<Uninhabited, T>`). This generalizes a previous change where we only did this for `T = ()`.

god I actually hate nested functions now lol. just use modules >:(

…use use behavior

WaffleLapkin · 2025-11-06T13:26:20Z

@bors try

@jackh726 I thinkt the cratere command should be @/craterbot check +rustflags=-Dunmustuse_in_always_ok, unless I'm missing something...

[DO NOT MERGE] crater proposed changes in unused must use lint

rust-log-analyzer · 2025-11-06T13:45:43Z

The job pr-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] build_helper test:false 0.700
error: this type will no longer be must used: std::result::Result<std::path::PathBuf, std::convert::Infallible>
   --> src/bootstrap/src/core/config/config.rs:738:34
    |
738 |           let initial_sysroot = t!(PathBuf::from_str(
    |  __________________________________^
739 | |             command(&initial_rustc)
740 | |                 .args(["--print", "sysroot"])
741 | |                 .run_in_dry_run()
...   |
744 | |                 .trim()
745 | |         ));
    | |_________^
    |
    = note: `-D unmustuse-in-always-ok` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(unmustuse_in_always_ok)]`

[RUSTC-TIMING] bootstrap test:false 9.892
error: could not compile `bootstrap` (lib) due to 1 previous error
Bootstrap failed while executing `clippy ci --stage 2`
Build completed unsuccessfully in 0:04:43

WaffleLapkin · 2025-11-06T13:56:14Z

for context:

lints emitted for libraries

warning: this type will no longer be must used: result::Result<&T, !>
   --> library/core/src/cell/once.rs:164:15
    |
164 |         match self.get_or_try_init(|| Ok::<T, !>(f())) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: result::Result<&mut T, !>
   --> library/core/src/cell/once.rs:200:15
    |
200 |         match self.get_mut_or_try_init(|| Ok::<T, !>(f())) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: result::Result<usize, Infallible>
   --> library/core/src/iter/adapters/step_by.rs:444:28
    |
421 | / macro_rules! spec_int_ranges {
422 | |     ($($t:ty)*) => ($(
423 | |
424 | |         const _: () = assert!(usize::BITS >= <$t>::BITS);
...   |
444 | |                 let step = <$t>::try_from(self.original_step().get()).unwrap_or(<$t>::MAX);
    | |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...   |
506 | |     )*)
507 | | }
    | |_- in this expansion of `spec_int_ranges!`
...
568 |   spec_int_ranges!(u8 u16 u32 u64 usize);
    |   -------------------------------------- in this macro invocation

warning: this type will no longer be must used: result::Result<usize, Infallible>
   --> library/core/src/iter/adapters/step_by.rs:493:28
    |
421 | / macro_rules! spec_int_ranges {
422 | |     ($($t:ty)*) => ($(
423 | |
424 | |         const _: () = assert!(usize::BITS >= <$t>::BITS);
...   |
493 | |                 let step = <$t>::try_from(self.original_step().get()).unwrap_or(<$t>::MAX);
    | |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...   |
506 | |     )*)
507 | | }
    | |_- in this expansion of `spec_int_ranges!`
...
568 |   spec_int_ranges!(u8 u16 u32 u64 usize);
    |   -------------------------------------- in this macro invocation

warning: this type will no longer be must used: result::Result<usize, Infallible>
   --> library/core/src/iter/range.rs:275:27
    |
248 | / macro_rules! step_integer_impls {
249 | |     {
250 | |         narrower than or same width as usize:
251 | |             $( [ $u_narrower:ident $i_narrower:ident ] ),+;
...   |
275 | |                     match Self::try_from(n) {
    | |                           ^^^^^^^^^^^^^^^^^
...   |
423 | |     };
424 | | }
    | |_- in this expansion of `step_integer_impls!`
...
427 | / step_integer_impls! {
428 | |     narrower than or same width as usize: [u8 i8], [u16 i16], [u32 i32], [u64 i64], [usize isize];
429 | |     wider than usize: [u128 i128];
430 | | }
    | |_- in this macro invocation

warning: this type will no longer be must used: result::Result<usize, Infallible>
   --> library/core/src/iter/range.rs:283:27
    |
248 | / macro_rules! step_integer_impls {
249 | |     {
250 | |         narrower than or same width as usize:
251 | |             $( [ $u_narrower:ident $i_narrower:ident ] ),+;
...   |
283 | |                     match Self::try_from(n) {
    | |                           ^^^^^^^^^^^^^^^^^
...   |
423 | |     };
424 | | }
    | |_- in this expansion of `step_integer_impls!`
...
427 | / step_integer_impls! {
428 | |     narrower than or same width as usize: [u8 i8], [u16 i16], [u32 i32], [u64 i64], [usize isize];
429 | |     wider than usize: [u128 i128];
430 | | }
    | |_- in this macro invocation

warning: this type will no longer be must used: result::Result<usize, Infallible>
   --> library/core/src/iter/range.rs:313:27
    |
248 | / macro_rules! step_integer_impls {
249 | |     {
250 | |         narrower than or same width as usize:
251 | |             $( [ $u_narrower:ident $i_narrower:ident ] ),+;
...   |
313 | |                     match $u_narrower::try_from(n) {
    | |                           ^^^^^^^^^^^^^^^^^^^^^^^^
...   |
423 | |     };
424 | | }
    | |_- in this expansion of `step_integer_impls!`
...
427 | / step_integer_impls! {
428 | |     narrower than or same width as usize: [u8 i8], [u16 i16], [u32 i32], [u64 i64], [usize isize];
429 | |     wider than usize: [u128 i128];
430 | | }
    | |_- in this macro invocation

warning: this type will no longer be must used: result::Result<usize, Infallible>
   --> library/core/src/iter/range.rs:334:27
    |
248 | / macro_rules! step_integer_impls {
249 | |     {
250 | |         narrower than or same width as usize:
251 | |             $( [ $u_narrower:ident $i_narrower:ident ] ),+;
...   |
334 | |                     match $u_narrower::try_from(n) {
    | |                           ^^^^^^^^^^^^^^^^^^^^^^^^
...   |
423 | |     };
424 | | }
    | |_- in this expansion of `step_integer_impls!`
...
427 | / step_integer_impls! {
428 | |     narrower than or same width as usize: [u8 i8], [u16 i16], [u32 i32], [u64 i64], [usize isize];
429 | |     wider than usize: [u128 i128];
430 | | }
    | |_- in this macro invocation

warning: this type will no longer be must used: result::Result<u32, Infallible>
  --> library/core/src/net/parser.rs:22:38
   |
17 | / macro_rules! impl_helper {
18 | |     ($($t:ty)*) => ($(impl ReadNumberHelper for $t {
19 | |         const ZERO: Self = 0;
20 | |         #[inline]
21 | |         fn checked_mul(&self, other: u32) -> Option<Self> {
22 | |             Self::checked_mul(*self, other.try_into().ok()?)
   | |                                      ^^^^^^^^^^^^^^^^
...  |
28 | |     })*)
29 | | }
   | |_- in this expansion of `impl_helper!`
30 |
31 |   impl_helper! { u8 u16 u32 }
   |   --------------------------- in this macro invocation

warning: this type will no longer be must used: result::Result<u32, Infallible>
  --> library/core/src/net/parser.rs:26:38
   |
17 | / macro_rules! impl_helper {
18 | |     ($($t:ty)*) => ($(impl ReadNumberHelper for $t {
19 | |         const ZERO: Self = 0;
20 | |         #[inline]
...  |
26 | |             Self::checked_add(*self, other.try_into().ok()?)
   | |                                      ^^^^^^^^^^^^^^^^
27 | |         }
28 | |     })*)
29 | | }
   | |_- in this expansion of `impl_helper!`
30 |
31 |   impl_helper! { u8 u16 u32 }
   |   --------------------------- in this macro invocation

warning: `core` (lib) generated 10 warnings
warning: this type will no longer be must used: Result<ByteString, Infallible>
   --> library/alloc/src/bstr.rs:328:53
    |
328 |       fn from_str(s: &str) -> Result<Self, Self::Err> {
    |  _____________________________________________________^
329 | |         Ok(ByteString(s.as_bytes().to_vec()))
330 | |     }
    | |_____^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<ByteString, Infallible>
   --> library/alloc/src/bstr.rs:329:9
    |
329 |         Ok(ByteString(s.as_bytes().to_vec()))
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: Result<String, Infallible>
    --> library/alloc/src/string.rs:2826:55
     |
2826 |       fn from_str(s: &str) -> Result<String, Self::Err> {
     |  _______________________________________________________^
2827 | |         Ok(String::from(s))
2828 | |     }
     | |_____^

warning: this type will no longer be must used: Result<String, Infallible>
    --> library/alloc/src/string.rs:2827:9
     |
2827 |         Ok(String::from(s))
     |         ^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: Result<InPlaceDrop<T>, !>
   --> library/alloc/src/vec/in_place_collect.rs:339:27
    |
339 |       move |mut sink, item| {
    |  ___________________________^
340 | |         unsafe {
...   |
350 | |         Ok(sink)
351 | |     }
    | |_____^

warning: this type will no longer be must used: Result<InPlaceDrop<T>, !>
   --> library/alloc/src/vec/in_place_collect.rs:350:9
    |
350 |         Ok(sink)
    |         ^^^^^^^^

warning: this type will no longer be must used: Result<InPlaceDrop<T>, !>
   --> library/alloc/src/vec/in_place_collect.rs:378:13
    |
378 |             self.try_fold::<_, _, Result<_, !>>(sink, write_in_place_with_drop(end)).into_ok();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: `alloc` (lib) generated 7 warnings
warning: this type will no longer be must used: core::result::Result<OsString, Infallible>
    --> library/std/src/ffi/os_str.rs:1747:53
     |
1747 |       fn from_str(s: &str) -> Result<Self, Self::Err> {
     |  _____________________________________________________^
1748 | |         Ok(OsString::from(s))
1749 | |     }
     | |_____^
     |
     = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: core::result::Result<OsString, Infallible>
    --> library/std/src/ffi/os_str.rs:1748:9
     |
1748 |         Ok(OsString::from(s))
     |         ^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<PathBuf, Infallible>
    --> library/std/src/path.rs:1978:53
     |
1978 |       fn from_str(s: &str) -> Result<Self, Self::Err> {
     |  _____________________________________________________^
1979 | |         Ok(PathBuf::from(s))
1980 | |     }
     | |_____^

warning: this type will no longer be must used: core::result::Result<PathBuf, Infallible>
    --> library/std/src/path.rs:1979:9
     |
1979 |         Ok(PathBuf::from(s))
     |         ^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<&T, !>
   --> library/std/src/sync/once_lock.rs:315:15
    |
315 |         match self.get_or_try_init(|| Ok::<T, !>(f())) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<&mut T, !>
   --> library/std/src/sync/once_lock.rs:355:15
    |
355 |         match self.get_mut_or_try_init(|| Ok::<T, !>(f())) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<i64, Infallible>
   --> library/std/src/sys/pal/unix/time.rs:197:21
    |
197 |             tv_sec: self.tv_sec.try_into().ok()?,
    |                     ^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<i64, Infallible>
   --> library/std/src/sys/pal/unix/time.rs:198:22
    |
198 |             tv_nsec: self.tv_nsec.as_inner().try_into().ok()?,
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<u32, Infallible>
    --> library/std/src/sys/fs/unix.rs:2395:50
     |
2395 |         cvt(unsafe { libc::mkfifo(path.as_ptr(), mode.try_into().unwrap()) }).map(|_| ())
     |                                                  ^^^^^^^^^^^^^^^

warning: this type will no longer be must used: core::result::Result<usize, Infallible>
   --> library/std/src/sys/process/unix/unix.rs:300:37
    |
300 |                 cvt(libc::setgroups(_g.len().try_into().unwrap(), _g.as_ptr()))?;
    |                                     ^^^^^^^^^^^^^^^^^^^

lints emitted for the compiler

warning: this type will no longer be must used: Result<&mut [T], !>
   --> compiler/rustc_arena/src/lib.rs:205:9
    |
205 |         self.try_alloc_from_iter(iter.into_iter().map(Ok::<T, !>)).into_ok()
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<&mut [T], !>
   --> compiler/rustc_arena/src/lib.rs:584:39
    |
584 |             (_, _) => outline(move || self.try_alloc_from_iter(iter.map(Ok::<T, !>)).into_ok()),
    |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: `rustc_arena` (lib) generated 2 warnings
warning: this type will no longer be must used: Result<OwnedSlice, !>
  --> compiler/rustc_data_structures/src/owned_slice.rs:62:5
   |
62 |     try_slice_owned(owner, |x| Ok::<_, !>(slicer(x))).into_ok()
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<&[u8], !>
  --> compiler/rustc_data_structures/src/owned_slice.rs:62:32
   |
62 |     try_slice_owned(owner, |x| Ok::<_, !>(slicer(x))).into_ok()
   |                                ^^^^^^^^^^^^^^^^^^^^^

warning: `rustc_data_structures` (lib) generated 2 warnings
warning: this type will no longer be must used: ControlFlow<!>
  --> compiler/rustc_ast_ir/src/visit.rs:22:52
   |
22 |       fn branch(self) -> ControlFlow<Self::Residual> {
   |  ____________________________________________________^
23 | |         ControlFlow::Continue(())
24 | |     }
   | |_____^
   |
   = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
  --> compiler/rustc_ast_ir/src/visit.rs:23:9
   |
23 |         ControlFlow::Continue(())
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^

warning: `rustc_ast_ir` (lib) generated 2 warnings
warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 774 | |             try_visit!(kind.walk(*span, *id, vis, ctxt, visitor));
     | |             ----------------------------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)
     |
     = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 809 | |                         try_visit!(vis.visit_fn(kind, span, id));
     | |                         ---------------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 868 | |                         try_visit!(vis.visit_fn(kind, span, id))
     | |                         ---------------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 898 | |                         try_visit!(vis.visit_fn(kind, span, id))
     | |                         ---------------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 931 | |             try_visit!(vis.visit_generics(generics));
     | |             ---------------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 936 | |             try_visit!(vis.visit_ty(self_ty));
     | |             --------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
 944 | |             try_visit!(vis.visit_method_receiver_expr(receiver));
     | |             ---------------------------------------------------- in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 |   macro_rules! try_visit {
     |   ---------------------- in this expansion of `try_visit!` (#2)
  46 |       ($e:expr) => {
  47 |           match $crate::visit::VisitorResult::branch($e) {
     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_ast/src/mut_visit.rs:262:1
     |
 262 |   super::common_visitor_and_walkers!((mut) MutVisitor);
     |   ---------------------------------------------------- in this macro invocation (#1)
     |
    ::: compiler/rustc_ast/src/visit.rs:313:1
     |
 313 | / macro_rules! common_visitor_and_walkers {
 314 | |     ($(($mut: ident))? $Visitor:ident$(<$lt:lifetime>)?) => {
 315 | |         $(${ignore($lt)}
 316 | |             #[derive(Copy, Clone)]
...    |
1000 | |                     try_visit!(vis.visit_fn(kind, *span, *id));
     | |                     ------------------------------------------ in this macro invocation (#2)
...    |
1112 | |     };
1113 | | }
     | |_- in this expansion of `super::common_visitor_and_walkers!` (#1)

warning: `rustc_ast` (lib) generated 8 warnings
warning: this type will no longer be must used: Result<i32, Infallible>
  --> compiler/rustc_error_messages/src/diagnostic_impls.rs:60:36
   |
53 | / macro_rules! into_diag_arg_for_number {
54 | |     ($( $ty:ty ),+ $(,)?) => {
55 | |         $(
56 | |             impl $crate::IntoDiagArg for $ty {
...  |
60 | |                     if let Ok(n) = TryInto::<i32>::try_into(self) {
   | |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...  |
69 | | }
   | |_- in this expansion of `into_diag_arg_for_number!`
...
83 |   into_diag_arg_for_number!(i8, u8, i16, u16, i32, u32, i64, u64, i128, u128, isize, usize);
   |   ----------------------------------------------------------------------------------------- in this macro invocation
   |
   = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: `rustc_error_messages` (lib) generated 1 warning
warning: this type will no longer be must used: Result<Arc<T>, Infallible>
   --> compiler/rustc_type_ir/src/fold.rs:308:15
    |
308 |         match fold_arc::<T, Infallible>(self, |t| Ok(t.fold_with(folder))) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: `rustc_type_ir` (lib) generated 1 warning
warning: this type will no longer be must used: Result<u64, Infallible>
   --> compiler/rustc_query_system/src/dep_graph/serialized.rs:762:33
    |
762 |         IntEncodedWithFixedSize(node_max.try_into().unwrap()).encode(&mut encoder);
    |                                 ^^^^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: `rustc_query_system` (lib) generated 1 warning
warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_ast_passes/src/ast_validation.rs:903:9
    |
903 |         walk_list!(self, visit_attribute, attrs);
    |         ---------------------------------------- in this macro invocation (#1)
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_ast_passes/src/ast_validation.rs:909:9
    |
909 |         walk_list!(self, visit_attribute, attrs);
    |         ---------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1050:21
     |
1050 |                     walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl { of_trait: true });
     |                     ----------------------------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1065:21
     |
1065 |                     walk_list!(this, visit_assoc_item, items, AssocCtxt::Impl { of_trait: false });
     |                     ------------------------------------------------------------------------------ in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1189:21
     |
1189 |                     walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits)
     |                     ------------------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1192:21
     |
1192 |                     walk_list!(this, visit_assoc_item, items, AssocCtxt::Trait);
     |                     ----------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1213:29
     |
1213 | ...                   walk_list!(this, visit_field_def, fields);
     |                       ----------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1228:29
     |
1228 | ...                   walk_list!(this, visit_field_def, fields);
     |                       ----------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1348:17
     |
1348 |                 walk_list!(self, visit_ty, &data.inputs);
     |                 ---------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_ast_passes/src/ast_validation.rs:1385:9
     |
1385 |         walk_list!(self, visit_generic_param, &generics.params);
     |         ------------------------------------------------------- in this macro invocation (#1)

warning: `rustc_ast_passes` (lib) generated 10 warnings
warning: this type will no longer be must used: Result<bool, !>
  --> compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs:56:26
   |
56 |           let Ok(result) = self.apply_inner::<!>(
   |  __________________________^
57 | |             tcx,
58 | |             typing_env,
59 | |             &mut Default::default(),
60 | |             &|id| Ok(tcx.is_descendant_of(module_def_id, id)),
61 | |             reveal_opaque,
62 | |         );
   | |_________^
   |
   = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<bool, !>
  --> compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs:60:19
   |
60 |             &|id| Ok(tcx.is_descendant_of(module_def_id, id)),
   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: Result<bool, !>
  --> compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs:75:13
   |
75 | /             self.apply_inner::<!>(tcx, typing_env, &mut Default::default(), &|_| Ok(true), &|_| {
76 | |                 None
77 | |             });
   | |______________^

warning: this type will no longer be must used: Result<bool, !>
  --> compiler/rustc_middle/src/ty/inhabitedness/inhabited_predicate.rs:75:82
   |
75 |             self.apply_inner::<!>(tcx, typing_env, &mut Default::default(), &|_| Ok(true), &|_| {
   |                                                                                  ^^^^^^^^

warning: this type will no longer be must used: Result<rustc_abi::TyAndLayout<'_, ty::Ty<'_>>, !>
    --> compiler/rustc_middle/src/ty/layout.rs:1110:38
     |
1110 | ...                   result = field.to_result().ok().and_then(|field| {
     |                                ^^^^^^^^^^^^^^^^^

warning: this type continue be must used: Result<IeeeFloat<HalfS>, Infallible>
    --> compiler/rustc_middle/src/ty/print/pretty.rs:1789:31
     |
1789 |                     let val = Half::try_from(int).unwrap();
     |                               ^^^^^^^^^^^^^^^^^^^
     |
     = note: `#[warn(mustuse_in_always_ok)]` on by default

warning: this type continue be must used: Result<IeeeFloat<SingleS>, Infallible>
    --> compiler/rustc_middle/src/ty/print/pretty.rs:1793:31
     |
1793 |                     let val = Single::try_from(int).unwrap();
     |                               ^^^^^^^^^^^^^^^^^^^^^

warning: this type continue be must used: Result<IeeeFloat<DoubleS>, Infallible>
    --> compiler/rustc_middle/src/ty/print/pretty.rs:1797:31
     |
1797 |                     let val = Double::try_from(int).unwrap();
     |                               ^^^^^^^^^^^^^^^^^^^^^

warning: this type continue be must used: Result<IeeeFloat<QuadS>, Infallible>
    --> compiler/rustc_middle/src/ty/print/pretty.rs:1801:31
     |
1801 |                     let val = Quad::try_from(int).unwrap();
     |                               ^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: Result<u128, Infallible>
   --> compiler/rustc_middle/src/ty/consts/int.rs:459:21
    |
451 | /  macro_rules! from_scalar_int_for_x {
452 | |      ($($ty:ty),*) => {
453 | |          $(
454 | |              impl From<ScalarInt> for $ty {
...   |
459 | |/                     int.to_uint(Size::from_bytes(size_of::<$ty>()))
460 | ||                        .try_into().unwrap()
    | ||__________________________________^
...   |
465 | |  }
    | |__- in this expansion of `from_scalar_int_for_x!`
...
468 |    from_scalar_int_for_x!(u8, u16, u32, u64, u128);
    |    ----------------------------------------------- in this macro invocation

warning: this type will no longer be must used: Result<i128, Infallible>
   --> compiler/rustc_middle/src/ty/consts/int.rs:509:21
    |
501 | /  macro_rules! from_scalar_int_for_x_signed {
502 | |      ($($ty:ty),*) => {
503 | |          $(
504 | |              impl From<ScalarInt> for $ty {
...   |
509 | |/                     int.to_int(Size::from_bytes(size_of::<$ty>()))
510 | ||                        .try_into().unwrap()
    | ||__________________________________^
...   |
515 | |  }
    | |__- in this expansion of `from_scalar_int_for_x_signed!`
...
518 |    from_scalar_int_for_x_signed!(i8, i16, i32, i64, i128);
    |    ------------------------------------------------------ in this macro invocation

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 58 | macro_rules! visit_opt {
    | ---------------------- in this expansion of `rustc_ast::visit::visit_opt!` (#1)
...
 61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
    |             --------------------------------------------------------------- in this macro invocation (#2)
    |
   ::: compiler/rustc_builtin_macros/src/deriving/coerce_pointee.rs:438:17
    |
438 |                 rustc_ast::visit::visit_opt!(error_on_pointee, visit_ty, default);
    |                 ----------------------------------------------------------------- in this macro invocation (#1)
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 58 | macro_rules! visit_opt {
    | ---------------------- in this expansion of `visit_opt!` (#1)
...
 61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
    |             --------------------------------------------------------------- in this macro invocation (#2)
    |
   ::: compiler/rustc_builtin_macros/src/deriving/default.rs:298:9
    |
298 |         visit_opt!(self, visit_anon_const, &v.disr_expr);
    |         ------------------------------------------------ in this macro invocation (#1)

warning: `rustc_builtin_macros` (lib) generated 2 warnings
warning: this type will no longer be must used: Result<u64, Infallible>
   --> compiler/rustc_transmute/src/layout/tree.rs:307:37
    |
307 |                     Ok(Self::number(width.try_into().unwrap()))
    |                                     ^^^^^^^^^^^^^^^^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<u64, Infallible>
   --> compiler/rustc_transmute/src/layout/tree.rs:312:37
    |
312 |                     Ok(Self::number(width.try_into().unwrap()))
    |                                     ^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: Result<u64, Infallible>
   --> compiler/rustc_transmute/src/layout/tree.rs:317:37
    |
317 |                     Ok(Self::number(width.try_into().unwrap()))
    |                                     ^^^^^^^^^^^^^^^^

warning: `rustc_transmute` (lib) generated 3 warnings
warning: `rustc_middle` (lib) generated 11 warnings
warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `visit::walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/build_reduced_graph.rs:1361:25
     |
1361 |                         visit::walk_list!(self, visit_attribute, &item.attrs);
     |                         ----------------------------------------------------- in this macro invocation (#1)
     |
     = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `visit::walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/build_reduced_graph.rs:1584:13
     |
1584 |             visit::walk_list!(self, visit_item, &krate.items);
     |             ------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `visit::walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/build_reduced_graph.rs:1585:13
     |
1585 |             visit::walk_list!(self, visit_attribute, &krate.attrs);
     |             ------------------------------------------------------ in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:1265:17
     |
1265 |                 walk_list!(self, visit_param_bound, bounds, BoundKind::Bound);
     |                 ------------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:1389:9
     |
1389 |         walk_list!(self, visit_attribute, &v.attrs);
     |         ------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:1411:9
     |
1411 |         walk_list!(self, visit_attribute, attrs);
     |         ---------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `try_visit!`
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_resolve/src/late.rs:1412:9
     |
1412 |         try_visit!(self.visit_vis(vis));
     |         ------------------------------- in this macro invocation

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  58 | macro_rules! visit_opt {
     | ---------------------- in this expansion of `visit_opt!` (#1)
...
  61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
     |             --------------------------------------------------------------- in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:1413:9
     |
1413 |         visit_opt!(self, visit_ident, ident);
     |         ------------------------------------ in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `try_visit!`
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
    ::: compiler/rustc_resolve/src/late.rs:1414:9
     |
1414 |         try_visit!(self.visit_ty(ty));
     |         ----------------------------- in this macro invocation

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:2641:29
     |
2641 | ...                   walk_list!(this, visit_param_bound, bounds, BoundKind::SuperTraits);
     |                       ------------------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:2660:29
     |
2660 | ...                   walk_list!(this, visit_param_bound, bounds, BoundKind::Bound);
     |                       ------------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  58 | macro_rules! visit_opt {
     | ---------------------- in this expansion of `visit_opt!` (#1)
...
  61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
     |             --------------------------------------------------------------- in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:3564:9
     |
3564 |         visit_opt!(self, visit_ty, &local.ty);
     |         ------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  58 | macro_rules! visit_opt {
     | ---------------------- in this expansion of `visit_opt!` (#1)
...
  61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
     |             --------------------------------------------------------------- in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:3761:13
     |
3761 |             visit_opt!(this, visit_expr, &arm.guard);
     |             ---------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  58 | macro_rules! visit_opt {
     | ---------------------- in this expansion of `visit_opt!` (#1)
...
  61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
     |             --------------------------------------------------------------- in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:3762:13
     |
3762 |             visit_opt!(this, visit_expr, &arm.body);
     |             --------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:4741:9
     |
4741 |         walk_list!(self, visit_attribute, f.attrs.iter());
     |         ------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
    --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
     |
  45 | macro_rules! try_visit {
     | ---------------------- in this expansion of `$crate::try_visit!` (#2)
  46 |     ($e:expr) => {
  47 |         match $crate::visit::VisitorResult::branch($e) {
     |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
  67 | macro_rules! walk_list {
     | ---------------------- in this expansion of `walk_list!` (#1)
...
  70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
     |             ------------------------------------------------------------------ in this macro invocation (#2)
     |
    ::: compiler/rustc_resolve/src/late.rs:4766:17
     |
4766 |                 walk_list!(self, resolve_expr_field, &se.fields, expr);
     |                 ------------------------------------------------------ in this macro invocation (#1)

warning: this type will no longer be must used: Result<(), !>
   --> compiler/rustc_trait_selection/src/traits/fulfill.rs:236:13
    |
236 | /             {
237 | |                 self.removed_predicates.extend(cycle.map(|c| c.obligation.clone()));
238 | |                 Ok(())
239 | |             }
    | |_____________^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<(), !>
   --> compiler/rustc_trait_selection/src/traits/fulfill.rs:238:17
    |
238 |                 Ok(())
    |                 ^^^^^^

warning: this type continue be must used: Result<Result<(), rustc_next_trait_solver::coherence::Conflict>, !>
    --> compiler/rustc_trait_selection/src/traits/select/mod.rs:1483:9
     |
1483 |         coherence::trait_ref_is_knowable(self.infcx, trait_ref, |ty| Ok::<_, !>(ty)).into_ok()
     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: `#[warn(mustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<rustc_middle::ty::Ty<'_>, !>
    --> compiler/rustc_trait_selection/src/traits/select/mod.rs:1483:70
     |
1483 |         coherence::trait_ref_is_knowable(self.infcx, trait_ref, |ty| Ok::<_, !>(ty)).into_ok()
     |                                                                      ^^^^^^^^^^^^^^

warning: this type will no longer be must used: ControlFlow<!>
   --> compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs:209:21
    |
209 |               let _ = self.for_each_item_bound::<!>(
    |  _____________________^
210 | |                 placeholder_trait_predicate.self_ty(),
211 | |                 |selcx, bound, idx, alias_bound_kind| {
212 | |                     let Some(bound) = bound.as_trait_clause() else {
...   |
251 | |                 || candidates.ambiguous = true,
252 | |             );
    | |_____________^

warning: this type will no longer be must used: ControlFlow<!>
   --> compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs:211:55
    |
211 |                   |selcx, bound, idx, alias_bound_kind| {
    |  _______________________________________________________^
212 | |                     let Some(bound) = bound.as_trait_clause() else {
213 | |                         return ControlFlow::Continue(());
214 | |                     };
...   |
248 | |                     ControlFlow::Continue(())
249 | |                 },
    | |_________________^

warning: this type will no longer be must used: ControlFlow<!>
   --> compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs:213:32
    |
213 |                         return ControlFlow::Continue(());
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: ControlFlow<!>
   --> compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs:216:32
    |
216 |                         return ControlFlow::Continue(());
    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^

warning: this type will no longer be must used: ControlFlow<!>
   --> compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs:248:21
    |
248 |                     ControlFlow::Continue(())
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^

warning: `rustc_resolve` (lib) generated 16 warnings
warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_lint/src/dangling.rs:241:57
    |
241 |                 self.with_inside_call_args(true, |this| walk_list!(this, visit_expr, args))
    |                                                         ---------------------------------- in this macro invocation (#1)
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_lint/src/dangling.rs:244:58
    |
244 |                 self.with_inside_call_args(false, |this| walk_list!(this, visit_stmt, stmts));
    |                                                          ----------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 58 | macro_rules! visit_opt {
    | ---------------------- in this expansion of `visit_opt!` (#1)
...
 61 |             $crate::try_visit!($visitor.$method(x $(, $($extra_args,)* )?));
    |             --------------------------------------------------------------- in this macro invocation (#2)
    |
   ::: compiler/rustc_lint/src/dangling.rs:245:17
    |
245 |                 visit_opt!(self, visit_expr, expr)
    |                 ---------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_lint/src/early.rs:311:9
    |
311 |         walk_list!(cx, visit_attribute, self.1);
    |         --------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_lint/src/early.rs:312:9
    |
312 |         walk_list!(cx, visit_item, self.2);
    |         ---------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: Result<rustc_middle::ty::Ty<'_>, !>
   --> compiler/rustc_hir_analysis/src/coherence/orphan.rs:308:51
    |
308 |       let lazily_normalize_ty = |user_ty: Ty<'tcx>| {
    |  ___________________________________________________^
309 | |         let ty::Alias(..) = user_ty.kind() else { return Ok(user_ty) };
310 | |
311 | |         let ocx = traits::ObligationCtxt::new(&infcx);
...   |
330 | |         Ok::<_, !>(ty)
331 | |     };
    | |_____^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<rustc_middle::ty::Ty<'_>, !>
   --> compiler/rustc_hir_analysis/src/coherence/orphan.rs:309:58
    |
309 |         let ty::Alias(..) = user_ty.kind() else { return Ok(user_ty) };
    |                                                          ^^^^^^^^^^^

warning: this type will no longer be must used: Result<rustc_middle::ty::Ty<'_>, !>
   --> compiler/rustc_hir_analysis/src/coherence/orphan.rs:316:20
    |
316 |             return Ok(user_ty);
    |                    ^^^^^^^^^^^

warning: this type will no longer be must used: Result<rustc_middle::ty::Ty<'_>, !>
   --> compiler/rustc_hir_analysis/src/coherence/orphan.rs:330:9
    |
330 |         Ok::<_, !>(ty)
    |         ^^^^^^^^^^^^^^

warning: this type continue be must used: Result<Result<(), OrphanCheckErr<rustc_middle::ty::TyCtxt<'_>, rustc_middle::ty::Ty<'_>>>, !>
   --> compiler/rustc_hir_analysis/src/coherence/orphan.rs:333:18
    |
333 |       let result = traits::orphan_check_trait_ref(
    |  __________________^
334 | |         &infcx,
335 | |         trait_ref,
336 | |         traits::InCrate::Local { mode },
337 | |         lazily_normalize_ty,
338 | |     )
    | |_____^
    |
    = note: `#[warn(mustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs:406:13
    |
406 |             walk_list!(this, visit_generic_param, trait_ref.bound_generic_params);
    |             --------------------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs:927:13
    |
927 |             walk_list!(this, visit_generic_param, generics.params);
    |             ------------------------------------------------------ in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs:928:13
    |
928 |             walk_list!(this, visit_where_predicate, generics.predicates);
    |             ------------------------------------------------------------ in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs:971:21
    |
971 |                     walk_list!(this, visit_generic_param, bound_generic_params);
    |                     ----------------------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs:973:21
    |
973 |                     walk_list!(this, visit_param_bound, bounds);
    |                     ------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs:982:17
    |
982 |                 walk_list!(self, visit_param_bound, bounds);
    |                 ------------------------------------------- in this macro invocation (#1)

warning: this type will no longer be must used: ControlFlow<!>
   --> /home/wffl/prog/rust-r/compiler/rustc_ast_ir/src/visit.rs:47:15
    |
 45 | macro_rules! try_visit {
    | ---------------------- in this expansion of `$crate::try_visit!` (#2)
 46 |     ($e:expr) => {
 47 |         match $crate::visit::VisitorResult::branch($e) {
    |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
 67 | macro_rules! walk_list {
    | ---------------------- in this expansion of `ast_visit::walk_list!` (#1)
...
 70 |             $crate::try_visit!($visitor.$method(elem $(, $($extra_args,)* )?));
    |             ------------------------------------------------------------------ in this macro invocation (#2)
    |
   ::: compiler/rustc_passes/src/input_stats.rs:459:9
    |
459 |         ast_visit::walk_list!(self, visit_path_segment, segments);
    |         --------------------------------------------------------- in this macro invocation (#1)
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: `rustc_lint` (lib) generated 5 warnings
warning: `rustc_passes` (lib) generated 1 warning
warning: `rustc_hir_analysis` (lib) generated 11 warnings
warning: this type will no longer be must used: Result<(), !>
   --> compiler/rustc_hir_typeck/src/expr_use_visitor.rs:253:68
    |
253 |       fn error_reported_in_ty(&self, _ty: Ty<'tcx>) -> Result<(), !> {
    |  ____________________________________________________________________^
254 | |         Ok(())
255 | |     }
    | |_____^
    |
    = note: `#[warn(unmustuse_in_always_ok)]` on by default

warning: this type will no longer be must used: Result<(), !>
   --> compiler/rustc_hir_typeck/src/expr_use_visitor.rs:254:9
    |
254 |         Ok(())
    |         ^^^^^^

warning: this type will no longer be must used: Result<(), !>
   --> compiler/rustc_hir_typeck/src/expr_use_visitor.rs:257:50
    |
257 |       fn tainted_by_errors(&self) -> Result<(), !> {
    |  __________________________________________________^
258 | |         Ok(())
259 | |     }
    | |_____^

warning: this type will no longer be must used: Result<(), !>
   --> compiler/rustc_hir_typeck/src/expr_use_visitor.rs:258:9
    |
258 |         Ok(())
    |         ^^^^^^

rust-bors · 2025-11-06T15:38:01Z

☀️ Try build successful (CI)
Build commit: 4f260f0 (4f260f0f20b3133d20cfb50353c0221943af5796, parent: 642c19bfc3a5c1de985bf5d0cc8207ac9d22708a)

jackh726 · 2025-11-10T17:21:28Z

@craterbot check +rustflags=-Dunmustuse_in_always_ok

craterbot · 2025-11-10T17:21:33Z

🚨 Error: failed to parse the command

🆘 If you have any trouble with Crater please ask in t-infra on Zulip
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

jackh726 · 2025-11-10T18:43:04Z

Hmm, let's try

@craterbot run mode=check-only start=642c19bfc3a5c1de985bf5d0cc8207ac9d22708a end=4f260f0f20b3133d20cfb50353c0221943af5796+rustflags=-Dunmustuse_in_always_ok

craterbot · 2025-11-10T18:43:07Z

🚨 Error: failed to parse the command

🆘 If you have any trouble with Crater please ask in t-infra on Zulip
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

WaffleLapkin · 2025-11-12T11:49:56Z

@craterbot run mode=check-only start=master#642c19bfc3a5c1de985bf5d0cc8207ac9d22708a end=try#4f260f0f20b3133d20cfb50353c0221943af5796+rustflags=-Dunmustuse_in_always_ok

craterbot · 2025-11-12T11:50:02Z

👌 Experiment pr-148577 created and queued.
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

craterbot · 2025-11-12T11:50:31Z

🚧 Experiment pr-148577 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

WaffleLapkin added 4 commits October 28, 2025 16:17

drive-by-cleanup: merge an early return into a match

622197b

add must_use tests for Result<MustUse/Struct, !>

f6839c9

consider Result<T, !>/ControlFlow<!, T> the same as T for must_…

17a892b

…use lint (or more accurately `Result<T, Uninhabited>`/`ControlFlow<Uninhabited, T>`). This generalizes a previous change where we only did this for `T = ()`.

move things outside

3ab6b23

god I actually hate nested functions now lol. just use modules >:(

rustbot assigned jackh726 Nov 6, 2025

WaffleLapkin added 2 commits November 6, 2025 14:22

add temporary lints for crater run(s), detecting proposed change in m…

6bc667a

…use use behavior

#![expect([un]mustuse_in_always_ok)]

310b963

WaffleLapkin force-pushed the unmustuse_in_always_ok branch from 7260bf5 to 310b963 Compare November 6, 2025 13:22

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rust-bors bot added a commit that referenced this pull request Nov 6, 2025

Auto merge of #148577 - WaffleLapkin:unmustuse_in_always_ok, r=<try>

4f260f0

[DO NOT MERGE] crater proposed changes in unused must use lint

craterbot added S-waiting-on-crater Status: Waiting on a crater run to be completed. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Nov 12, 2025

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