When encountering an expected named lifetime and none are present, suggest adding one

18 files changed, 157 insertions, 29 deletions

diff --git a/src/test/ui/error-codes/E0106.rs b/src/test/ui/error-codes/E0106.rs
index d6537d12363..cc3438727a8 100644
--- a/src/test/ui/error-codes/E0106.rs
+++ b/src/test/ui/error-codes/E0106.rs
@@ -16,7 +16,7 @@ struct Buzz<'a, 'b>(&'a str, &'b str);
 struct Quux {
     baz: Baz,
     //~^ ERROR E0106
-    //~| expected lifetime parameter
+    //~| expected named lifetime parameter
     buzz: Buzz,
     //~^ ERROR E0106
     //~| expected 2 lifetime parameters
diff --git a/src/test/ui/error-codes/E0106.stderr b/src/test/ui/error-codes/E0106.stderr
index cea9581e701..bb7efa90c80 100644
--- a/src/test/ui/error-codes/E0106.stderr
+++ b/src/test/ui/error-codes/E0106.stderr
@@ -2,25 +2,49 @@ error[E0106]: missing lifetime specifier
   --> $DIR/E0106.rs:2:8
    |
 LL |     x: &bool,
-   |        ^ expected lifetime parameter
+   |        ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct Foo<'lifetime> {
+LL |     x: &'lifetime bool,
+   |
 
 error[E0106]: missing lifetime specifier
   --> $DIR/E0106.rs:7:7
    |
 LL |     B(&bool),
-   |       ^ expected lifetime parameter
+   |       ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | enum Bar<'lifetime> {
+LL |     A(u8),
+LL |     B(&'lifetime bool),
+   |
 
 error[E0106]: missing lifetime specifier
   --> $DIR/E0106.rs:10:14
    |
 LL | type MyStr = &str;
-   |              ^ expected lifetime parameter
+   |              ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | type MyStr<'lifetime> = &'lifetime str;
+   |           ^^^^^^^^^^^   ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/E0106.rs:17:10
    |
 LL |     baz: Baz,
-   |          ^^^ expected lifetime parameter
+   |          ^^^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct Quux<'lifetime> {
+LL |     baz: Baz<'lifetime>,
+   |
 
 error[E0106]: missing lifetime specifiers
   --> $DIR/E0106.rs:20:11
diff --git a/src/test/ui/impl-header-lifetime-elision/assoc-type.stderr b/src/test/ui/impl-header-lifetime-elision/assoc-type.stderr
index 492ca872187..0835970df40 100644
--- a/src/test/ui/impl-header-lifetime-elision/assoc-type.stderr
+++ b/src/test/ui/impl-header-lifetime-elision/assoc-type.stderr
@@ -2,13 +2,23 @@ error[E0106]: missing lifetime specifier
   --> $DIR/assoc-type.rs:11:19
    |
 LL |     type Output = &i32;
-   |                   ^ expected lifetime parameter
+   |                   ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL |     type Output<'lifetime> = &'lifetime i32;
+   |                ^^^^^^^^^^^   ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/assoc-type.rs:16:20
    |
 LL |     type Output = &'_ i32;
-   |                    ^^ expected lifetime parameter
+   |                    ^^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL |     type Output<'lifetime> = &'lifetime i32;
+   |                ^^^^^^^^^^^    ^^^^^^^^^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/in-band-lifetimes/issue-61124-anon-lifetime-in-struct-declaration.stderr b/src/test/ui/in-band-lifetimes/issue-61124-anon-lifetime-in-struct-declaration.stderr
index 9579abb76b3..32507e21d27 100644
--- a/src/test/ui/in-band-lifetimes/issue-61124-anon-lifetime-in-struct-declaration.stderr
+++ b/src/test/ui/in-band-lifetimes/issue-61124-anon-lifetime-in-struct-declaration.stderr
@@ -2,7 +2,12 @@ error[E0106]: missing lifetime specifier
   --> $DIR/issue-61124-anon-lifetime-in-struct-declaration.rs:8:19
    |
 LL | struct Heartbreak(Betrayal);
-   |                   ^^^^^^^^ expected lifetime parameter
+   |                   ^^^^^^^^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct Heartbreak<'lifetime>(Betrayal<'lifetime>);
+   |                  ^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-19707.stderr b/src/test/ui/issues/issue-19707.stderr
index c85ce0eb3a7..51a8aabb483 100644
--- a/src/test/ui/issues/issue-19707.stderr
+++ b/src/test/ui/issues/issue-19707.stderr
@@ -2,17 +2,25 @@ error[E0106]: missing lifetime specifier
   --> $DIR/issue-19707.rs:3:28
    |
 LL | type Foo = fn(&u8, &u8) -> &u8;
-   |                            ^ expected lifetime parameter
+   |                            ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
+help: consider introducing a named lifetime
+   |
+LL | type Foo<'lifetime> = fn(&u8, &u8) -> &'lifetime u8;
+   |         ^^^^^^^^^^^                   ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/issue-19707.rs:5:27
    |
 LL | fn bar<F: Fn(&u8, &u8) -> &u8>(f: &F) {}
-   |                           ^ expected lifetime parameter
+   |                           ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
+help: consider introducing a named lifetime
+   |
+LL | fn bar<'lifetime, F: Fn(&u8, &u8) -> &'lifetime u8>(f: &F) {}
+   |        ^^^^^^^^^^                    ^^^^^^^^^^
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-26638.stderr b/src/test/ui/issues/issue-26638.stderr
index 6d7c1b0c43f..8396c932c5b 100644
--- a/src/test/ui/issues/issue-26638.stderr
+++ b/src/test/ui/issues/issue-26638.stderr
@@ -2,9 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/issue-26638.rs:1:62
    |
 LL | fn parse_type(iter: Box<dyn Iterator<Item=&str>+'static>) -> &str { iter.next() }
-   |                                                              ^ expected lifetime parameter
+   |                                                              ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say which one of `iter`'s 2 lifetimes it is borrowed from
+help: consider introducing a named lifetime
+   |
+LL | fn parse_type<'lifetime>(iter: Box<dyn Iterator<Item=&str>+'static>) -> &'lifetime str { iter.next() }
+   |              ^^^^^^^^^^^                                                ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/issue-26638.rs:4:40
diff --git a/src/test/ui/issues/issue-30255.stderr b/src/test/ui/issues/issue-30255.stderr
index c53129b7f29..64f89496caa 100644
--- a/src/test/ui/issues/issue-30255.stderr
+++ b/src/test/ui/issues/issue-30255.stderr
@@ -2,25 +2,37 @@ error[E0106]: missing lifetime specifier
   --> $DIR/issue-30255.rs:9:24
    |
 LL | fn f(a: &S, b: i32) -> &i32 {
-   |                        ^ expected lifetime parameter
+   |                        ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say which one of `a`'s 2 lifetimes it is borrowed from
+help: consider introducing a named lifetime
+   |
+LL | fn f<'lifetime>(a: &S, b: i32) -> &'lifetime i32 {
+   |     ^^^^^^^^^^^                   ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/issue-30255.rs:14:34
    |
 LL | fn g(a: &S, b: bool, c: &i32) -> &i32 {
-   |                                  ^ expected lifetime parameter
+   |                                  ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from one of `a`'s 2 lifetimes or `c`
+help: consider introducing a named lifetime
+   |
+LL | fn g<'lifetime>(a: &S, b: bool, c: &i32) -> &'lifetime i32 {
+   |     ^^^^^^^^^^^                             ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/issue-30255.rs:19:44
    |
 LL | fn h(a: &bool, b: bool, c: &S, d: &i32) -> &i32 {
-   |                                            ^ expected lifetime parameter
+   |                                            ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from `a`, one of `c`'s 2 lifetimes, or `d`
+help: consider introducing a named lifetime
+   |
+LL | fn h<'lifetime>(a: &bool, b: bool, c: &S, d: &i32) -> &'lifetime i32 {
+   |     ^^^^^^^^^^^                                       ^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 
diff --git a/src/test/ui/lifetimes/lifetime-elision-return-type-requires-explicit-lifetime.stderr b/src/test/ui/lifetimes/lifetime-elision-return-type-requires-explicit-lifetime.stderr
index 3f7c3934a0b..075ea3c691f 100644
--- a/src/test/ui/lifetimes/lifetime-elision-return-type-requires-explicit-lifetime.stderr
+++ b/src/test/ui/lifetimes/lifetime-elision-return-type-requires-explicit-lifetime.stderr
@@ -10,17 +10,25 @@ error[E0106]: missing lifetime specifier
   --> $DIR/lifetime-elision-return-type-requires-explicit-lifetime.rs:7:33
    |
 LL | fn g(_x: &isize, _y: &isize) -> &isize {
-   |                                 ^ expected lifetime parameter
+   |                                 ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from `_x` or `_y`
+help: consider introducing a named lifetime
+   |
+LL | fn g<'lifetime>(_x: &isize, _y: &isize) -> &'lifetime isize {
+   |     ^^^^^^^^^^^                            ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/lifetime-elision-return-type-requires-explicit-lifetime.rs:17:19
    |
 LL | fn h(_x: &Foo) -> &isize {
-   |                   ^ expected lifetime parameter
+   |                   ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say which one of `_x`'s 2 lifetimes it is borrowed from
+help: consider introducing a named lifetime
+   |
+LL | fn h<'lifetime>(_x: &Foo) -> &'lifetime isize {
+   |     ^^^^^^^^^^^              ^^^^^^^^^^
 
 error[E0106]: missing lifetime specifier
   --> $DIR/lifetime-elision-return-type-requires-explicit-lifetime.rs:21:20
diff --git a/src/test/ui/lifetimes/lifetime-errors/ex1b-return-no-names-if-else.stderr b/src/test/ui/lifetimes/lifetime-errors/ex1b-return-no-names-if-else.stderr
index a4e0d71a3fa..f95b4cb16be 100644
--- a/src/test/ui/lifetimes/lifetime-errors/ex1b-return-no-names-if-else.stderr
+++ b/src/test/ui/lifetimes/lifetime-errors/ex1b-return-no-names-if-else.stderr
@@ -2,9 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/ex1b-return-no-names-if-else.rs:1:29
    |
 LL | fn foo(x: &i32, y: &i32) -> &i32 {
-   |                             ^ expected lifetime parameter
+   |                             ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from `x` or `y`
+help: consider introducing a named lifetime
+   |
+LL | fn foo<'lifetime>(x: &i32, y: &i32) -> &'lifetime i32 {
+   |       ^^^^^^^^^^^                      ^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/proc-macro/item-error.stderr b/src/test/ui/proc-macro/item-error.stderr
index e801c26c43b..19bbadbcd41 100644
--- a/src/test/ui/proc-macro/item-error.stderr
+++ b/src/test/ui/proc-macro/item-error.stderr
@@ -2,7 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/item-error.rs:10:8
    |
 LL |     a: &u64
-   |        ^ expected lifetime parameter
+   |        ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct A<'lifetime> {
+LL |     a: &'lifetime u64
+   |
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-in-enums-anon.stderr b/src/test/ui/regions/regions-in-enums-anon.stderr
index ae06e7653db..6e653452f55 100644
--- a/src/test/ui/regions/regions-in-enums-anon.stderr
+++ b/src/test/ui/regions/regions-in-enums-anon.stderr
@@ -2,7 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/regions-in-enums-anon.rs:4:9
    |
 LL |     Bar(&isize)
-   |         ^ expected lifetime parameter
+   |         ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | enum Foo<'lifetime> {
+LL |     Bar(&'lifetime isize)
+   |
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/regions/regions-in-structs-anon.stderr b/src/test/ui/regions/regions-in-structs-anon.stderr
index a1d4ebb597b..b40990e3edb 100644
--- a/src/test/ui/regions/regions-in-structs-anon.stderr
+++ b/src/test/ui/regions/regions-in-structs-anon.stderr
@@ -2,7 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/regions-in-structs-anon.rs:4:8
    |
 LL |     x: &isize
-   |        ^ expected lifetime parameter
+   |        ^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct Foo<'lifetime> {
+LL |     x: &'lifetime isize
+   |
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/rfc1623.stderr b/src/test/ui/rfc1623.stderr
index 171c00ba7b8..5b665e18141 100644
--- a/src/test/ui/rfc1623.stderr
+++ b/src/test/ui/rfc1623.stderr
@@ -2,7 +2,7 @@ error[E0106]: missing lifetime specifier
   --> $DIR/rfc1623.rs:8:42
    |
 LL | static NON_ELIDABLE_FN: &fn(&u8, &u8) -> &u8 =
-   |                                          ^ expected lifetime parameter
+   |                                          ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
 
@@ -10,7 +10,7 @@ error[E0106]: missing lifetime specifier
   --> $DIR/rfc1623.rs:10:39
    |
 LL |     &(non_elidable as fn(&u8, &u8) -> &u8);
-   |                                       ^ expected lifetime parameter
+   |                                       ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
 
diff --git a/src/test/ui/unboxed-closures/unboxed-closure-sugar-lifetime-elision.stderr b/src/test/ui/unboxed-closures/unboxed-closure-sugar-lifetime-elision.stderr
index 9fb9a07166f..3b101bf304a 100644
--- a/src/test/ui/unboxed-closures/unboxed-closure-sugar-lifetime-elision.stderr
+++ b/src/test/ui/unboxed-closures/unboxed-closure-sugar-lifetime-elision.stderr
@@ -2,9 +2,18 @@ error[E0106]: missing lifetime specifier
   --> $DIR/unboxed-closure-sugar-lifetime-elision.rs:26:39
    |
 LL |     let _: dyn Foo(&isize, &usize) -> &usize;
-   |                                       ^ expected lifetime parameter
+   |                                       ^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or argument 2
+help: consider introducing a named lifetime
+   |
+LL | fn main<'lifetime>() {
+LL |     eq::< dyn for<'a> Foo<(&'a isize,), Output=&'a isize>,
+LL |           dyn Foo(&isize) -> &isize                                   >();
+LL |     eq::< dyn for<'a> Foo<(&'a isize,), Output=(&'a isize, &'a isize)>,
+LL |           dyn Foo(&isize) -> (&isize, &isize)                           >();
+LL | 
+ ...
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr b/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr
index b20c23ade2b..c06891d2308 100644
--- a/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr
+++ b/src/test/ui/underscore-lifetime/dyn-trait-underscore-in-struct.stderr
@@ -2,7 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/dyn-trait-underscore-in-struct.rs:9:24
    |
 LL |     x: Box<dyn Debug + '_>,
-   |                        ^^ expected lifetime parameter
+   |                        ^^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct Foo<'lifetime> {
+LL |     x: Box<dyn Debug + 'lifetime>,
+   |
 
 error[E0228]: the lifetime bound for this object type cannot be deduced from context; please supply an explicit bound
   --> $DIR/dyn-trait-underscore-in-struct.rs:9:12
diff --git a/src/test/ui/underscore-lifetime/in-fn-return-illegal.stderr b/src/test/ui/underscore-lifetime/in-fn-return-illegal.stderr
index ed61bdfddda..bdfb8ce4d83 100644
--- a/src/test/ui/underscore-lifetime/in-fn-return-illegal.stderr
+++ b/src/test/ui/underscore-lifetime/in-fn-return-illegal.stderr
@@ -2,9 +2,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/in-fn-return-illegal.rs:5:30
    |
 LL | fn foo(x: &u32, y: &u32) -> &'_ u32 { loop { } }
-   |                              ^^ expected lifetime parameter
+   |                              ^^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from `x` or `y`
+help: consider introducing a named lifetime
+   |
+LL | fn foo<'lifetime>(x: &u32, y: &u32) -> &'lifetime u32 { loop { } }
+   |       ^^^^^^^^^^^                       ^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/underscore-lifetime/in-struct.stderr b/src/test/ui/underscore-lifetime/in-struct.stderr
index 6bbdc71195a..46dc3f899a1 100644
--- a/src/test/ui/underscore-lifetime/in-struct.stderr
+++ b/src/test/ui/underscore-lifetime/in-struct.stderr
@@ -2,13 +2,25 @@ error[E0106]: missing lifetime specifier
   --> $DIR/in-struct.rs:6:9
    |
 LL |     x: &'_ u32,
-   |         ^^ expected lifetime parameter
+   |         ^^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | struct Foo<'lifetime> {
+LL |     x: &'lifetime u32,
+   |
 
 error[E0106]: missing lifetime specifier
   --> $DIR/in-struct.rs:10:14
    |
 LL |     Variant(&'_ u32),
-   |              ^^ expected lifetime parameter
+   |              ^^ expected named lifetime parameter
+   |
+help: consider introducing a named lifetime
+   |
+LL | enum Bar<'lifetime> {
+LL |     Variant(&'lifetime u32),
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/underscore-lifetime/underscore-lifetime-binders.stderr b/src/test/ui/underscore-lifetime/underscore-lifetime-binders.stderr
index ef9e7e39df0..6c2159bc661 100644
--- a/src/test/ui/underscore-lifetime/underscore-lifetime-binders.stderr
+++ b/src/test/ui/underscore-lifetime/underscore-lifetime-binders.stderr
@@ -14,7 +14,7 @@ error[E0106]: missing lifetime specifier
   --> $DIR/underscore-lifetime-binders.rs:2:17
    |
 LL | struct Baz<'a>(&'_ &'a u8);
-   |                 ^^ expected lifetime parameter
+   |                 ^^ help: consider using the named lifetime: `'a`
 
 error[E0106]: missing lifetime specifier
   --> $DIR/underscore-lifetime-binders.rs:10:33
@@ -28,9 +28,13 @@ error[E0106]: missing lifetime specifier
   --> $DIR/underscore-lifetime-binders.rs:16:35
    |
 LL | fn foo2(_: &'_ u8, y: &'_ u8) -> &'_ u8 { y }
-   |                                   ^^ expected lifetime parameter
+   |                                   ^^ expected named lifetime parameter
    |
    = help: this function's return type contains a borrowed value, but the signature does not say whether it is borrowed from argument 1 or `y`
+help: consider introducing a named lifetime
+   |
+LL | fn foo2<'lifetime>(_: &'_ u8, y: &'_ u8) -> &'lifetime u8 { y }
+   |        ^^^^^^^^^^^                           ^^^^^^^^^
 
 error: aborting due to 5 previous errors