Esteban Küber 49bb371ca7 When single impl can satisfy inference error, suggest type ...

When encountering an inference error where a return type must be known, like when calling `Iterator::sum::<T>()` without specifying `T`, look for all `T` that would satisfy `Sum<S>`. If only one, suggest it.

```
error[E0283]: type annotations needed
  --> $DIR/cannot-infer-iterator-sum-return-type.rs:4:9
   |
LL |     let sum = v
   |         ^^^
...
LL |         .sum(); // `sum::<T>` needs `T` to be specified
   |          --- type must be known at this point
   |
   = note: cannot satisfy `_: Sum<i32>`
help: the trait `Sum` is implemented for `i32`
  --> $SRC_DIR/core/src/iter/traits/accum.rs:LL:COL
  ::: $SRC_DIR/core/src/iter/traits/accum.rs:LL:COL
   |
   = note: in this macro invocation
note: required by a bound in `std::iter::Iterator::sum`
  --> $SRC_DIR/core/src/iter/traits/iterator.rs:LL:COL
   = note: this error originates in the macro `integer_sum_product` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider giving `sum` an explicit type, where the type for type parameter `S` is specified
   |
LL |     let sum: i32 = v
   |            +++++
```

2026-03-18 18:16:47 +00:00

..

auxiliary

Remove some unnecessary allow(incomplete_features)

2024-03-11 19:42:04 +00:00

cg-in-dyn-issue-128176.rs

Remove dyn_compatible_for_dispatch

2025-02-24 18:48:40 +00:00

cg-in-dyn-issue-128176.stderr

mGCA: Make traits with type assoc consts dyn compatible...

2026-01-21 12:53:44 +01:00

index_array_bad_type.rs

Properly check that array length is valid type during built-in unsizing in index

2025-01-28 17:52:28 +00:00

index_array_bad_type.stderr

Properly check that array length is valid type during built-in unsizing in index

2025-01-28 17:52:28 +00:00

issue-56445-1.full.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-56445-1.min.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-56445-1.rs

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-56445-2.rs

Use more principled check for generics in const ops

2026-01-01 18:12:34 -08:00

issue-56445-2.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-56445-3.rs

Use more principled check for generics in const ops

2026-01-01 18:12:34 -08:00

issue-56445-3.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-60818-struct-constructors.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-61336-1.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-61336-2.rs

…

issue-61336-2.stderr

Use trait name instead of full constraint in suggestion message

2024-12-07 21:29:58 +00:00

issue-61336.rs

…

issue-61336.stderr

Use trait name instead of full constraint in suggestion message

2024-12-07 21:29:58 +00:00

issue-61422.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-61432.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-62187-encountered-polymorphic-const.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-62878.full.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-62878.min.stderr

stabilize gai

2025-06-11 15:30:15 +01:00

issue-62878.rs

stabilize gai

2025-06-11 15:30:15 +01:00

issue-63322-forbid-dyn.full.stderr

Fix the testcases to not use UnsizedConstParamTy

2025-09-15 09:01:22 +00:00

issue-63322-forbid-dyn.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-63322-forbid-dyn.rs

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-64519.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-66596-impl-trait-for-str-const-arg.rs

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-66906.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-67185-1.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-67185-2.rs

…

issue-67185-2.stderr

Remove unhelpful hint from trivial bound errors

2026-02-24 00:04:45 -05:00

issue-67375.full.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-67375.min.stderr

Improve the diagnostics for unused generic parameters

2024-02-01 16:18:03 +01:00

issue-67375.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-67739.full.stderr

Provide structured suggestion for unconstrained generic constant

2024-03-21 00:03:59 +00:00

issue-67739.min.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-67739.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-67945-1.full.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-67945-1.min.stderr

Improve the diagnostics for unused generic parameters

2024-02-01 16:18:03 +01:00

issue-67945-1.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-67945-2.full.stderr

Tweak multispan rendering

2024-12-12 23:36:27 +00:00

issue-67945-2.min.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-67945-2.rs

Use more principled check for generics in const ops

2026-01-01 18:12:34 -08:00

issue-67945-3.full.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-67945-3.min.stderr

Improve the diagnostics for unused generic parameters

2024-02-01 16:18:03 +01:00

issue-67945-3.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-67945-4.full.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-67945-4.min.stderr

Improve the diagnostics for unused generic parameters

2024-02-01 16:18:03 +01:00

issue-67945-4.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-68104-print-stack-overflow.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-68366.full.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-68366.min.stderr

rustc_resolve: Improve resolve_const_param_in_non_trivial_anon_const wording

2025-06-07 13:01:16 +02:00

issue-68366.rs

UI tests: add missing diagnostic kinds where possible

2025-04-08 23:06:31 +03:00

issue-68596.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-68615-adt.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-68615-adt.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-68615-array.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-68615-array.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-69654-run-pass.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-69654-run-pass.stderr

bless tests with new lint messages

2025-08-19 21:27:10 +02:00

issue-70125-1.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-70125-2.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-70167.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-70180-1-stalled_on.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-70180-2-stalled_on.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-70225.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-70273-assoc-fn.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-71169.full.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-71169.min.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-71169.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-71202.rs

Fix tests

2025-05-21 20:20:19 +01:00

issue-71202.stderr

Avoid looking at HIR for trait and impl items

2025-06-30 08:45:43 +00:00

issue-71381.full.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-71381.min.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-71381.rs

Avoid follow-up errors and ICEs after missing lifetime errors on data structures

2024-07-11 11:00:15 +00:00

issue-71382.full.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-71382.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-71382.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-71547.rs

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-71611.full.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-71611.min.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-71611.rs

Allow type_of to return partially non-error types if the type was already tainted

2024-05-28 11:55:20 +00:00

issue-71986.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-72352.full.stderr

Use the correct char type on all platforms

2024-02-14 11:12:19 +00:00

issue-72352.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-72352.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-72845.rs

…

issue-72845.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-73120.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-73260.rs

…

issue-73260.stderr

…

issue-73491.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-73491.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-73727-static-reference-array-const-param.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-73727-static-reference-array-const-param.rs

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-74101.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-74101.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-74255.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-74255.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-74906.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-74950.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-74950.rs

UI tests: add missing diagnostic kinds where possible

2025-04-08 23:06:31 +03:00

issue-75047.min.stderr

fix(hir_analysis/wfcheck): don't leak {type error}

2024-09-29 23:40:43 -05:00

issue-75047.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-75299.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-76701-ty-param-in-const.rs

…

issue-76701-ty-param-in-const.stderr

rustc_resolve: Improve resolve_const_param_in_non_trivial_anon_const wording

2025-06-07 13:01:16 +02:00

issue-79674.rs

…

issue-79674.stderr

Deduplicate more sized errors on call exprs

2024-01-24 02:53:15 +00:00

issue-80062.rs

…

issue-80062.stderr

generic_const_exprs: suggest to add the feature, not use it

2023-11-30 20:59:51 +01:00

issue-80375.rs

…

issue-80375.stderr

rustc_resolve: Improve resolve_const_param_in_non_trivial_anon_const wording

2025-06-07 13:01:16 +02:00

issue-82956.rs

Unify wording of resolve error

2026-02-17 16:51:44 +00:00

issue-82956.stderr

Unify wording of resolve error

2026-02-17 16:51:44 +00:00

issue-83249.rs

…

issue-83249.stderr

When single impl can satisfy inference error, suggest type

2026-03-18 18:16:47 +00:00

issue-83288.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-83466.rs

…

issue-83466.stderr

bless tests with new lint messages

2025-08-19 21:27:10 +02:00

issue-83765.rs

Fix tests

2025-05-21 20:20:19 +01:00

issue-83765.stderr

Fix tests

2025-05-21 20:20:19 +01:00

issue-84659.fixed

Provide structured suggestion for unconstrained generic constant

2024-03-21 00:03:59 +00:00

issue-84659.rs

Provide structured suggestion for unconstrained generic constant

2024-03-21 00:03:59 +00:00

issue-84659.stderr

Provide structured suggestion for unconstrained generic constant

2024-03-21 00:03:59 +00:00

issue-85031-2.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-85031-2.stderr

…

issue-86033.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-86530.rs

…

issue-86530.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-86535-2.rs

Marks ADT live if it appears in pattern

2025-06-14 13:44:43 +08:00

issue-86535-2.stderr

bless tests with new lint messages

2025-08-19 21:27:10 +02:00

issue-86535.rs

Marks ADT live if it appears in pattern

2025-06-14 13:44:43 +08:00

issue-86535.stderr

bless tests with new lint messages

2025-08-19 21:27:10 +02:00

issue-86820.rs

…

issue-86820.stderr

Show number in error message even for one error

2023-11-24 19:15:52 +01:00

issue-87076.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-87470.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-87493.rs

…

issue-87493.stderr

Show diff suggestion format on verbose replacement

2025-02-10 20:21:39 +00:00

issue-87964.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-88119.rs

Cleanup some ui tests for const-traits

2026-01-06 17:23:16 +00:00

issue-88468.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-88997.rs

…

issue-88997.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-89146.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-89304.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-89320.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-89334.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-90318.rs

Stabilize const TypeId::of

2025-07-21 09:11:21 +00:00

issue-90318.stderr

Stabilize const TypeId::of

2025-07-21 09:11:21 +00:00

issue-90364.rs

…

issue-90364.stderr

Introduce feature(generic_const_parameter_types)

2025-02-28 20:43:15 +00:00

issue-90455.fixed

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-90455.rs

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-90455.stderr

Provide structured suggestion for unconstrained generic constant

2024-03-21 00:03:59 +00:00

issue-92186.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-96654.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-97278.rs

…

issue-97278.stderr

Improve derive suggestion of const param

2025-09-24 13:29:23 +00:00

issue-97634.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-98629.rs

Remove #[const_trait]

2025-11-08 07:37:15 +01:00

issue-98629.stderr

Remove #[const_trait]

2025-11-08 07:37:15 +01:00

issue-99641.rs

…

issue-99641.stderr

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00

issue-100313.rs

Ignore tests for the parallel frontend

2026-03-17 17:39:59 +08:00

issue-100313.stderr

const-eval error: always say in which item the error occurred

2025-06-07 13:42:30 +02:00

issue-105037.rs

[AUTO-GENERATED] Migrate ui tests from // to //@ directives

2024-02-16 20:02:50 +00:00

issue-105821.rs

Split part of adt_const_params into unsized_const_params

2024-07-17 11:01:29 +01:00