Rollup merge of rust-lang#66186 - GuillaumeGomez:long-err-explanation…

…-E0623, r=Dylan-DPC

Add long error explanation for E0623

Part of rust-lang#61137.

r? @Dylan-DPC

src/librustc/error_codes.rs

@@ -1896,6 +1896,51 @@ fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32 {
 ```
 "##,
 
+E0623: r##"
+A lifetime didn't match what was expected.
+
+Erroneous code example:
+
+```compile_fail,E0623
+struct Foo<'a> {
+    x: &'a isize,
+}
+
+fn bar<'short, 'long>(c: Foo<'short>, l: &'long isize) {
+    let _: Foo<'long> = c; // error!
+}
+```
+
+In this example, we tried to set a value with an incompatible lifetime to
+another one (`'long` is unrelated to `'short`). We can solve this issue in
+two different ways:
+
+Either we make `'short` live at least as long as `'long`:
+
+```
+struct Foo<'a> {
+    x: &'a isize,
+}
+
+// we set 'short to live at least as long as 'long
+fn bar<'short: 'long, 'long>(c: Foo<'short>, l: &'long isize) {
+    let _: Foo<'long> = c; // ok!
+}
+```
+
+Or we use only one lifetime:
+
+```
+struct Foo<'a> {
+    x: &'a isize,
+}
+
+fn bar<'short>(c: Foo<'short>, l: &'short isize) {
+    let _: Foo<'short> = c; // ok!
+}
+```
+"##,
+
 E0635: r##"
 The `#![feature]` attribute specified an unknown feature.
 
@@ -2329,7 +2374,6 @@ the future, [RFC 2091] prohibits their implementation without a follow-up RFC.
     E0488, // lifetime of variable does not enclose its declaration
     E0489, // type/lifetime parameter not in scope here
     E0490, // a value of type `..` is borrowed for too long
-    E0623, // lifetime mismatch where both parameters are anonymous regions
     E0628, // generators cannot have explicit parameters
     E0631, // type mismatch in closure arguments
     E0637, // "'_" is not a valid lifetime bound

src/test/ui/associated-type-bounds/implied-region-constraints.stderr

@@ -18,3 +18,4 @@ LL |             let _failure_proves_not_implied_outlives_region_b: &'b T = &x;
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/associated-types/associated-types-project-from-hrtb-in-fn-body.stderr

@@ -11,3 +11,4 @@ LL |     let z: I::A = if cond { x } else { y };
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/associated-types/associated-types-subtyping-1.stderr

@@ -18,3 +18,4 @@ LL |     let _c: <T as Trait<'a>>::Type = b;
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/associated-types/cache/project-fn-ret-contravariant.krisskross.stderr

@@ -22,3 +22,4 @@ LL |    (a, b)
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/associated-types/cache/project-fn-ret-invariant.krisskross.stderr

@@ -21,3 +21,4 @@ LL |    let b = bar(foo, x);
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/associated-types/cache/project-fn-ret-invariant.oneuse.stderr

@@ -11,3 +11,4 @@ LL |    let b = bar(f, y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/async-await/issues/issue-63388-1.stderr

@@ -11,3 +11,4 @@ LL |         foo
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/async-await/multiple-lifetimes/ret-impl-trait-one.stderr

@@ -9,3 +9,4 @@ LL | async fn async_ret_impl_trait1<'a, 'b>(a: &'a u8, b: &'b u8) -> impl Trait<
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/borrowck/borrowck-reborrow-from-shorter-lived-andmut.stderr

@@ -10,3 +10,4 @@ LL |     S { pointer: &mut *p.pointer }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/continue-after-missing-main.stderr

@@ -21,4 +21,5 @@ LL |     let _: AdaptedMatrixProvider<'original_data, MP> = tableau.provider().c
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0601`.
+Some errors have detailed explanations: E0601, E0623.
+For more information about an error, try `rustc --explain E0601`.

src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr

@@ -77,4 +77,5 @@ LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
 
 error: aborting due to 5 previous errors
 
-For more information about this error, try `rustc --explain E0310`.
+Some errors have detailed explanations: E0310, E0623.
+For more information about an error, try `rustc --explain E0310`.

src/test/ui/in-band-lifetimes/mismatched.stderr

@@ -16,4 +16,5 @@ LL | fn foo2(x: &'a u32, y: &'b u32) -> &'a u32 { y }
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0621`.
+Some errors have detailed explanations: E0621, E0623.
+For more information about an error, try `rustc --explain E0621`.

src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr

@@ -22,3 +22,4 @@ LL |         x
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/issues/issue-17728.stderr

@@ -29,4 +29,5 @@ LL | |     }
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0623.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/lifetimes/lifetime-errors/ex1-return-one-existing-name-if-else-using-impl.stderr

@@ -11,3 +11,4 @@ LL |         if x > y { x } else { y }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex1-return-one-existing-name-return-type-is-anon.stderr

@@ -11,3 +11,4 @@ LL |     x
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex1-return-one-existing-name-self-is-anon.stderr

@@ -11,3 +11,4 @@ LL |         if true { x } else { self }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex2b-push-no-existing-names.stderr

@@ -8,3 +8,4 @@ LL |     x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex2c-push-inference-variable.stderr

@@ -9,3 +9,4 @@ LL |     x.push(z);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex2d-push-inference-variable-2.stderr

@@ -8,3 +8,4 @@ LL |     let a: &mut Vec<Ref<i32>> = x;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex2e-push-inference-variable-3.stderr

@@ -8,3 +8,4 @@ LL |     let a: &mut Vec<Ref<i32>> = x;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-2.stderr

@@ -8,3 +8,4 @@ LL |     *v = x;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-3.stderr

@@ -16,3 +16,4 @@ LL |     z.push((x,y));
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-both-are-structs-2.stderr

@@ -8,3 +8,4 @@ LL |     x.b = y.b;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-both-are-structs-3.stderr

@@ -8,3 +8,4 @@ LL |     x.a = x.b;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-both-are-structs-earlybound-regions.stderr

@@ -9,3 +9,4 @@ LL |     x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-both-are-structs-latebound-regions.stderr

@@ -8,3 +8,4 @@ LL |     x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-both-are-structs.stderr

@@ -8,3 +8,4 @@ LL |     x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-latebound-regions.stderr

@@ -8,3 +8,4 @@ LL |     x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-one-is-struct-2.stderr

@@ -10,3 +10,4 @@ LL |     y = x.b;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-one-is-struct-3.stderr

@@ -8,3 +8,4 @@ LL |     y.b = x;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-one-is-struct-4.stderr

@@ -8,3 +8,4 @@ LL |     y.b = x;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-one-is-struct.stderr

@@ -8,3 +8,4 @@ LL |     x.b = y;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-return-type-is-anon.stderr

@@ -10,3 +10,4 @@ LL |     x
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-self-is-anon.stderr

@@ -10,3 +10,4 @@ LL |         if true { x } else { self }
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-fn-items.stderr

@@ -8,3 +8,4 @@ LL |   y.push(z);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-impl-items.stderr

@@ -8,3 +8,4 @@ LL |         x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions-using-trait-objects.stderr

@@ -8,3 +8,4 @@ LL |   y.push(z);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/lifetimes/lifetime-errors/ex3-both-anon-regions.stderr

@@ -8,3 +8,4 @@ LL |     x.push(y);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/object-lifetime/object-lifetime-default-mybox.stderr

@@ -27,4 +27,5 @@ LL | fn load2<'a>(ss: &MyBox<dyn SomeTrait + 'a>) -> MyBox<dyn SomeTrait + 'a> {
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0623.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/regions/region-lifetime-bounds-on-fns-where-clause.stderr

@@ -27,4 +27,5 @@ LL |     let _: fn(&mut &isize, &mut &isize) = a;
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0623.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/regions/region-multiple-lifetime-bounds-on-fns-where-clause.stderr

@@ -38,4 +38,5 @@ LL |     let _: fn(&mut &isize, &mut &isize, &mut &isize) = a;
 
 error: aborting due to 4 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0623.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/regions/regions-bounded-method-type-parameters-cross-crate.stderr

@@ -9,3 +9,4 @@ LL |     a.bigger_region(b)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-bounded-method-type-parameters-trait-bound.stderr

@@ -9,3 +9,4 @@ LL |     f.method(b);
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-creating-enums3.stderr

@@ -10,3 +10,4 @@ LL |     Ast::Add(x, y)
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-free-region-ordering-callee.stderr

@@ -22,3 +22,4 @@ LL |     let z: &'b usize = &*x;
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-free-region-ordering-caller.migrate.stderr

@@ -29,3 +29,4 @@ LL |     let z: Option<&'a &'b usize> = None;
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-infer-contravariance-due-to-decl.stderr

@@ -12,3 +12,4 @@ LL |     let _: Contravariant<'long> = c;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-infer-covariance-due-to-decl.stderr

@@ -11,3 +11,4 @@ LL |     let _: Covariant<'short> = c;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-lifetime-bounds-on-fns.stderr

@@ -27,4 +27,5 @@ LL |     let _: fn(&mut &isize, &mut &isize) = a;
 
 error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0623.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/regions/regions-reborrow-from-shorter-mut-ref-mut-ref.stderr

@@ -10,3 +10,4 @@ LL |     &mut ***p
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-reborrow-from-shorter-mut-ref.stderr

@@ -10,3 +10,4 @@ LL |     &mut **p
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-variance-contravariant-use-covariant-in-second-position.stderr

@@ -9,3 +9,4 @@ LL |     let _: S<'long, 'long> = c;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-variance-contravariant-use-covariant.stderr

@@ -12,3 +12,4 @@ LL |     let _: Contravariant<'long> = c;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-variance-covariant-use-contravariant.stderr

@@ -11,3 +11,4 @@ LL |     let _: Covariant<'short> = c;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/regions/regions-variance-invariant-use-contravariant.stderr

@@ -11,3 +11,4 @@ LL |     let _: Invariant<'short> = c;
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/arbitrary_self_types_pin_lifetime_mismatch-async.stderr

@@ -24,3 +24,4 @@ LL |     async fn bar<'a>(self: Alias<&Self>, arg: &'a ()) -> &() { arg }
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/arbitrary_self_types_pin_lifetime_mismatch.stderr

@@ -24,3 +24,4 @@ LL |     fn bar<'a>(self: Alias<&Self>, arg: &'a ()) -> &() { arg }
 
 error: aborting due to 3 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/elision/lt-ref-self-async.stderr

@@ -60,3 +60,4 @@ LL |         f
 
 error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/elision/lt-ref-self.stderr

@@ -60,3 +60,4 @@ LL |         f
 
 error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/elision/ref-mut-self-async.stderr

@@ -60,3 +60,4 @@ LL |         f
 
 error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/elision/ref-mut-self.stderr

@@ -60,3 +60,4 @@ LL |         f
 
 error: aborting due to 6 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/elision/ref-mut-struct-async.stderr

@@ -50,3 +50,4 @@ LL |         f
 
 error: aborting due to 5 previous errors
 
+For more information about this error, try `rustc --explain E0623`.

src/test/ui/self/elision/ref-mut-struct.stderr

@@ -50,3 +50,4 @@ LL |         f
 
 error: aborting due to 5 previous errors
 
+For more information about this error, try `rustc --explain E0623`.