Auto merge of #91517 - matthiaskrgr:rollup-3fmp4go, r=matthiaskrgr

Rollup of 3 pull requests

Successful merges:

 - #87054 (Add a `try_reduce` method to the Iterator trait)
 - #89701 (Updated error message for accidental uses of derive attribute as a crate attribute)
 - #90519 (Keep spans for generics in `#[derive(_)]` desugaring)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

17 files changed, 470 insertions, 23 deletions

diff --git a/src/test/ui/derives/issue-36617.rs b/src/test/ui/derives/issue-36617.rs
index 08fc82e91f6..08f293d2ebb 100644
--- a/src/test/ui/derives/issue-36617.rs
+++ b/src/test/ui/derives/issue-36617.rs
@@ -1,3 +1,16 @@
 #![derive(Copy)] //~ ERROR cannot determine resolution for the attribute macro `derive`
+//~^ ERROR `derive` attribute cannot be used at crate level
+
+#![test]//~ ERROR cannot determine resolution for the attribute macro `test`
+//~^ ERROR `test` attribute cannot be used at crate level
+
+#![test_case]//~ ERROR cannot determine resolution for the attribute macro `test_case`
+//~^ ERROR `test_case` attribute cannot be used at crate level
+
+#![bench]//~ ERROR cannot determine resolution for the attribute macro `bench`
+//~^ ERROR `bench` attribute cannot be used at crate level
+
+#![global_allocator]//~ ERROR cannot determine resolution for the attribute macro `global_allocator`
+//~^ ERROR `global_allocator` attribute cannot be used at crate level
 
 fn main() {}
diff --git a/src/test/ui/derives/issue-36617.stderr b/src/test/ui/derives/issue-36617.stderr
index 0716764b427..9cc0a29b065 100644
--- a/src/test/ui/derives/issue-36617.stderr
+++ b/src/test/ui/derives/issue-36617.stderr
@@ -6,5 +6,92 @@ LL | #![derive(Copy)]
    |
    = note: import resolution is stuck, try simplifying macro imports
 
-error: aborting due to previous error
+error: cannot determine resolution for the attribute macro `test`
+  --> $DIR/issue-36617.rs:4:4
+   |
+LL | #![test]
+   |    ^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: cannot determine resolution for the attribute macro `test_case`
+  --> $DIR/issue-36617.rs:7:4
+   |
+LL | #![test_case]
+   |    ^^^^^^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: cannot determine resolution for the attribute macro `bench`
+  --> $DIR/issue-36617.rs:10:4
+   |
+LL | #![bench]
+   |    ^^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: cannot determine resolution for the attribute macro `global_allocator`
+  --> $DIR/issue-36617.rs:13:4
+   |
+LL | #![global_allocator]
+   |    ^^^^^^^^^^^^^^^^
+   |
+   = note: import resolution is stuck, try simplifying macro imports
+
+error: `derive` attribute cannot be used at crate level
+  --> $DIR/issue-36617.rs:1:1
+   |
+LL | #![derive(Copy)]
+   | ^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[derive(Copy)]
+   | ~~~~~~~~~~~~~~~
+
+error: `test` attribute cannot be used at crate level
+  --> $DIR/issue-36617.rs:4:1
+   |
+LL | #![test]
+   | ^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[test]
+   | ~~~~~~~
+
+error: `test_case` attribute cannot be used at crate level
+  --> $DIR/issue-36617.rs:7:1
+   |
+LL | #![test_case]
+   | ^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[test_case]
+   | ~~~~~~~~~~~~
+
+error: `bench` attribute cannot be used at crate level
+  --> $DIR/issue-36617.rs:10:1
+   |
+LL | #![bench]
+   | ^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[bench]
+   | ~~~~~~~~
+
+error: `global_allocator` attribute cannot be used at crate level
+  --> $DIR/issue-36617.rs:13:1
+   |
+LL | #![global_allocator]
+   | ^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[global_allocator]
+   | ~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 10 previous errors
 
diff --git a/src/test/ui/feature-gates/issue-43106-gating-of-bench.rs b/src/test/ui/feature-gates/issue-43106-gating-of-bench.rs
index 31eee88d1fa..796325b79af 100644
--- a/src/test/ui/feature-gates/issue-43106-gating-of-bench.rs
+++ b/src/test/ui/feature-gates/issue-43106-gating-of-bench.rs
@@ -6,5 +6,5 @@
 
 #![bench                   = "4100"]
 //~^ ERROR cannot determine resolution for the attribute macro `bench`
-
+//~^^ ERROR `bench` attribute cannot be used at crate level
 fn main() {}
diff --git a/src/test/ui/feature-gates/issue-43106-gating-of-bench.stderr b/src/test/ui/feature-gates/issue-43106-gating-of-bench.stderr
index d0305c5160f..6b332211942 100644
--- a/src/test/ui/feature-gates/issue-43106-gating-of-bench.stderr
+++ b/src/test/ui/feature-gates/issue-43106-gating-of-bench.stderr
@@ -6,5 +6,16 @@ LL | #![bench                   = "4100"]
    |
    = note: import resolution is stuck, try simplifying macro imports
 
-error: aborting due to previous error
+error: `bench` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-bench.rs:7:1
+   |
+LL | #![bench                   = "4100"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[bench                   = "4100"]
+   |
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr b/src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
index 9e2e2d4137d..f94ec7d4704 100644
--- a/src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
+++ b/src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs-error.stderr
@@ -129,36 +129,66 @@ error: `macro_export` attribute cannot be used at crate level
    |
 LL | #![macro_export]
    | ^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[macro_export]
+   |
 
 error: `rustc_main` attribute cannot be used at crate level
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:14:1
    |
 LL | #![rustc_main]
    | ^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[rustc_main]
+   | ~~~~~~~~~~~~~
 
 error: `start` attribute cannot be used at crate level
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:16:1
    |
 LL | #![start]
    | ^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[start]
+   |
 
 error: `repr` attribute cannot be used at crate level
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:18:1
    |
 LL | #![repr()]
    | ^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[repr()]
+   |
 
 error: `path` attribute cannot be used at crate level
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:20:1
    |
 LL | #![path = "3800"]
    | ^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[path = "3800"]
+   |
 
 error: `automatically_derived` attribute cannot be used at crate level
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:22:1
    |
 LL | #![automatically_derived]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[automatically_derived]
+   |
 
 error[E0518]: attribute should be applied to function or closure
   --> $DIR/issue-43106-gating-of-builtin-attrs-error.rs:36:17
diff --git a/src/test/ui/feature-gates/issue-43106-gating-of-test.rs b/src/test/ui/feature-gates/issue-43106-gating-of-test.rs
index ee3fe712e36..39835c9268e 100644
--- a/src/test/ui/feature-gates/issue-43106-gating-of-test.rs
+++ b/src/test/ui/feature-gates/issue-43106-gating-of-test.rs
@@ -3,5 +3,5 @@
 #![allow(soft_unstable)]
 #![test                    = "4200"]
 //~^ ERROR cannot determine resolution for the attribute macro `test`
-
+//~^^ ERROR `test` attribute cannot be used at crate level
 fn main() {}
diff --git a/src/test/ui/feature-gates/issue-43106-gating-of-test.stderr b/src/test/ui/feature-gates/issue-43106-gating-of-test.stderr
index 335af5e7905..300a9966dd8 100644
--- a/src/test/ui/feature-gates/issue-43106-gating-of-test.stderr
+++ b/src/test/ui/feature-gates/issue-43106-gating-of-test.stderr
@@ -6,5 +6,16 @@ LL | #![test                    = "4200"]
    |
    = note: import resolution is stuck, try simplifying macro imports
 
-error: aborting due to previous error
+error: `test` attribute cannot be used at crate level
+  --> $DIR/issue-43106-gating-of-test.rs:4:1
+   |
+LL | #![test                    = "4200"]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[test                    = "4200"]
+   |
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/imports/issue-28134.rs b/src/test/ui/imports/issue-28134.rs
index 1ed2d330b51..ef2a5d634a6 100644
--- a/src/test/ui/imports/issue-28134.rs
+++ b/src/test/ui/imports/issue-28134.rs
@@ -2,3 +2,4 @@
 
 #![allow(soft_unstable)]
 #![test] //~ ERROR cannot determine resolution for the attribute macro `test`
+//~^ ERROR 4:1: 4:9: `test` attribute cannot be used at crate level
diff --git a/src/test/ui/imports/issue-28134.stderr b/src/test/ui/imports/issue-28134.stderr
index 8ed4d015f32..33cb53f202a 100644
--- a/src/test/ui/imports/issue-28134.stderr
+++ b/src/test/ui/imports/issue-28134.stderr
@@ -6,5 +6,16 @@ LL | #![test]
    |
    = note: import resolution is stuck, try simplifying macro imports
 
-error: aborting due to previous error
+error: `test` attribute cannot be used at crate level
+  --> $DIR/issue-28134.rs:4:1
+   |
+LL | #![test]
+   | ^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[test]
+   | ~~~~~~~
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/issues/issue-38821.stderr b/src/test/ui/issues/issue-38821.stderr
index e53a543f3a0..cdf1f0dfc53 100644
--- a/src/test/ui/issues/issue-38821.stderr
+++ b/src/test/ui/issues/issue-38821.stderr
@@ -10,6 +10,10 @@ note: required because of the requirements on the impl of `IntoNullable` for `<C
 LL | impl<T: NotNull> IntoNullable for T {
    |                  ^^^^^^^^^^^^     ^
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider further restricting the associated type
+   |
+LL |     Expr: Expression<SqlType=<Col::SqlType as IntoNullable>::Nullable>, <Col as Expression>::SqlType: NotNull,
+   |                                                                       +++++++++++++++++++++++++++++++++++++++
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/issues/issue-50480.rs b/src/test/ui/issues/issue-50480.rs
index deb63872f69..10597caf5b2 100644
--- a/src/test/ui/issues/issue-50480.rs
+++ b/src/test/ui/issues/issue-50480.rs
@@ -1,8 +1,17 @@
 #[derive(Clone, Copy)]
 //~^ ERROR the trait `Copy` may not be implemented for this type
-struct Foo(NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 //~^ ERROR cannot find type `NotDefined` in this scope
 //~| ERROR cannot find type `NotDefined` in this scope
+//~| ERROR cannot find type `N` in this scope
+//~| ERROR cannot find type `N` in this scope
+//~| ERROR `i32` is not an iterator
+
+#[derive(Clone, Copy)]
+//~^ ERROR the trait `Copy` may not be implemented for this type
+struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+//~^ ERROR cannot find type `NotDefined` in this scope
+//~| ERROR cannot find type `N` in this scope
 //~| ERROR `i32` is not an iterator
 
 fn main() {}
diff --git a/src/test/ui/issues/issue-50480.stderr b/src/test/ui/issues/issue-50480.stderr
index 15f38c89267..0bb1f9ae035 100644
--- a/src/test/ui/issues/issue-50480.stderr
+++ b/src/test/ui/issues/issue-50480.stderr
@@ -1,20 +1,61 @@
-error[E0412]: cannot find type `NotDefined` in this scope
+error[E0412]: cannot find type `N` in this scope
   --> $DIR/issue-50480.rs:3:12
    |
-LL | struct Foo(NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
-   |            ^^^^^^^^^^ not found in this scope
+LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |           -^ not found in this scope
+   |           |
+   |           help: you might be missing a type parameter: `<N>`
 
 error[E0412]: cannot find type `NotDefined` in this scope
+  --> $DIR/issue-50480.rs:3:15
+   |
+LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |               ^^^^^^^^^^ not found in this scope
+
+error[E0412]: cannot find type `N` in this scope
   --> $DIR/issue-50480.rs:3:12
    |
-LL | struct Foo(NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
-   |            ^^^^^^^^^^ not found in this scope
+LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |           -^ not found in this scope
+   |           |
+   |           help: you might be missing a type parameter: `<N>`
+
+error[E0412]: cannot find type `NotDefined` in this scope
+  --> $DIR/issue-50480.rs:3:15
+   |
+LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |           -   ^^^^^^^^^^ not found in this scope
+   |           |
+   |           help: you might be missing a type parameter: `<NotDefined>`
+
+error[E0412]: cannot find type `N` in this scope
+  --> $DIR/issue-50480.rs:12:18
+   |
+LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |            -     ^
+   |            |
+   |            similarly named type parameter `T` defined here
+   |
+help: a type parameter with a similar name exists
+   |
+LL | struct Bar<T>(T, T, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |                  ~
+help: you might be missing a type parameter
+   |
+LL | struct Bar<T, N>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |             +++
+
+error[E0412]: cannot find type `NotDefined` in this scope
+  --> $DIR/issue-50480.rs:12:21
+   |
+LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |                     ^^^^^^^^^^ not found in this scope
 
 error[E0277]: `i32` is not an iterator
-  --> $DIR/issue-50480.rs:3:24
+  --> $DIR/issue-50480.rs:3:27
    |
-LL | struct Foo(NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
-   |                        ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
+LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
    |
    = help: the trait `Iterator` is not implemented for `i32`
    = note: if you want to iterate between `start` until a value `end`, use the exclusive range syntax `start..end` or the inclusive range syntax `start..=end`
@@ -25,14 +66,36 @@ error[E0204]: the trait `Copy` may not be implemented for this type
 LL | #[derive(Clone, Copy)]
    |                 ^^^^
 LL |
-LL | struct Foo(NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
-   |                                                 --------  ------ this field does not implement `Copy`
-   |                                                 |
-   |                                                 this field does not implement `Copy`
+LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |                                                    --------  ------ this field does not implement `Copy`
+   |                                                    |
+   |                                                    this field does not implement `Copy`
+   |
+   = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: `i32` is not an iterator
+  --> $DIR/issue-50480.rs:12:33
+   |
+LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |                                 ^^^^^^^^^^^^^^^^^^^^^^^ `i32` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `i32`
+   = note: if you want to iterate between `start` until a value `end`, use the exclusive range syntax `start..end` or the inclusive range syntax `start..=end`
+
+error[E0204]: the trait `Copy` may not be implemented for this type
+  --> $DIR/issue-50480.rs:10:17
+   |
+LL | #[derive(Clone, Copy)]
+   |                 ^^^^
+LL |
+LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
+   |                                                          --------  ------ this field does not implement `Copy`
+   |                                                          |
+   |                                                          this field does not implement `Copy`
    |
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 4 previous errors
+error: aborting due to 10 previous errors
 
 Some errors have detailed explanations: E0204, E0277, E0412.
 For more information about an error, try `rustc --explain E0204`.
diff --git a/src/test/ui/lifetimes/undeclared-lifetime-used-in-debug-macro-issue-70152.stderr b/src/test/ui/lifetimes/undeclared-lifetime-used-in-debug-macro-issue-70152.stderr
index e18d725faef..a2086895234 100644
--- a/src/test/ui/lifetimes/undeclared-lifetime-used-in-debug-macro-issue-70152.stderr
+++ b/src/test/ui/lifetimes/undeclared-lifetime-used-in-debug-macro-issue-70152.stderr
@@ -11,9 +11,8 @@ LL |     a: &'b str,
 error[E0261]: use of undeclared lifetime name `'b`
   --> $DIR/undeclared-lifetime-used-in-debug-macro-issue-70152.rs:3:9
    |
-LL | #[derive(Eq, PartialEq)]
-   |          -- lifetime `'b` is missing in item created through this procedural macro
 LL | struct Test {
+   |            - help: consider introducing lifetime `'b` here: `<'b>`
 LL |     a: &'b str,
    |         ^^ undeclared lifetime
    |
diff --git a/src/test/ui/span/issue-43927-non-ADT-derive.rs b/src/test/ui/span/issue-43927-non-ADT-derive.rs
index 840c12e16e1..935bfa001bf 100644
--- a/src/test/ui/span/issue-43927-non-ADT-derive.rs
+++ b/src/test/ui/span/issue-43927-non-ADT-derive.rs
@@ -1,5 +1,6 @@
 #![derive(Debug, PartialEq, Eq)] // should be an outer attribute!
 //~^ ERROR cannot determine resolution for the attribute macro `derive`
+//~^^ ERROR `derive` attribute cannot be used at crate level
 struct DerivedOn;
 
 fn main() {}
diff --git a/src/test/ui/span/issue-43927-non-ADT-derive.stderr b/src/test/ui/span/issue-43927-non-ADT-derive.stderr
index 9ef81c5150a..e3ae37e3689 100644
--- a/src/test/ui/span/issue-43927-non-ADT-derive.stderr
+++ b/src/test/ui/span/issue-43927-non-ADT-derive.stderr
@@ -6,5 +6,16 @@ LL | #![derive(Debug, PartialEq, Eq)] // should be an outer attribute!
    |
    = note: import resolution is stuck, try simplifying macro imports
 
-error: aborting due to previous error
+error: `derive` attribute cannot be used at crate level
+  --> $DIR/issue-43927-non-ADT-derive.rs:1:1
+   |
+LL | #![derive(Debug, PartialEq, Eq)] // should be an outer attribute!
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: perhaps you meant to use an outer attribute
+   |
+LL | #[derive(Debug, PartialEq, Eq)] // should be an outer attribute!
+   | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+error: aborting due to 2 previous errors
 
diff --git a/src/test/ui/suggestions/derive-macro-missing-bounds.rs b/src/test/ui/suggestions/derive-macro-missing-bounds.rs
new file mode 100644
index 00000000000..56c218f97eb
--- /dev/null
+++ b/src/test/ui/suggestions/derive-macro-missing-bounds.rs
@@ -0,0 +1,89 @@
+mod a {
+    use std::fmt::{Debug, Formatter, Result};
+    struct Inner<T>(T);
+
+    impl Debug for Inner<()> {
+        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+            todo!()
+        }
+    }
+
+    #[derive(Debug)]
+    struct Outer<T>(Inner<T>); //~ ERROR `a::Inner<T>` doesn't implement `Debug`
+}
+
+mod b {
+    use std::fmt::{Debug, Formatter, Result};
+    struct Inner<T>(T);
+
+    impl<T: Debug> Debug for Inner<T> {
+        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+            todo!()
+        }
+    }
+
+    #[derive(Debug)]
+    struct Outer<T>(Inner<T>);
+}
+
+mod c {
+    use std::fmt::{Debug, Formatter, Result};
+    struct Inner<T>(T);
+    trait Trait {}
+
+    impl<T: Debug + Trait> Debug for Inner<T> {
+        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+            todo!()
+        }
+    }
+
+    #[derive(Debug)]
+    struct Outer<T>(Inner<T>); //~ ERROR the trait bound `T: c::Trait` is not satisfied
+}
+
+mod d {
+    use std::fmt::{Debug, Formatter, Result};
+    struct Inner<T>(T);
+    trait Trait {}
+
+    impl<T> Debug for Inner<T> where T: Debug, T: Trait {
+        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+            todo!()
+        }
+    }
+
+    #[derive(Debug)]
+    struct Outer<T>(Inner<T>); //~ ERROR the trait bound `T: d::Trait` is not satisfied
+}
+
+mod e {
+    use std::fmt::{Debug, Formatter, Result};
+    struct Inner<T>(T);
+    trait Trait {}
+
+    impl<T> Debug for Inner<T> where T: Debug + Trait {
+        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+            todo!()
+        }
+    }
+
+    #[derive(Debug)]
+    struct Outer<T>(Inner<T>); //~ ERROR the trait bound `T: e::Trait` is not satisfied
+}
+
+mod f {
+    use std::fmt::{Debug, Formatter, Result};
+    struct Inner<T>(T);
+    trait Trait {}
+
+    impl<T: Debug> Debug for Inner<T> where T: Trait {
+        fn fmt(&self, f: &mut Formatter<'_>) -> Result {
+            todo!()
+        }
+    }
+
+    #[derive(Debug)]
+    struct Outer<T>(Inner<T>); //~ ERROR the trait bound `T: f::Trait` is not satisfied
+}
+
+fn main() {}
diff --git a/src/test/ui/suggestions/derive-macro-missing-bounds.stderr b/src/test/ui/suggestions/derive-macro-missing-bounds.stderr
new file mode 100644
index 00000000000..7a4f7e209c1
--- /dev/null
+++ b/src/test/ui/suggestions/derive-macro-missing-bounds.stderr
@@ -0,0 +1,107 @@
+error[E0277]: `a::Inner<T>` doesn't implement `Debug`
+  --> $DIR/derive-macro-missing-bounds.rs:12:21
+   |
+LL |     #[derive(Debug)]
+   |              ----- in this derive macro expansion
+LL |     struct Outer<T>(Inner<T>);
+   |                     ^^^^^^^^ `a::Inner<T>` cannot be formatted using `{:?}`
+   |
+   = help: the trait `Debug` is not implemented for `a::Inner<T>`
+   = note: add `#[derive(Debug)]` to `a::Inner<T>` or manually `impl Debug for a::Inner<T>`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider introducing a `where` bound, but there might be an alternative better way to express this requirement
+   |
+LL |     struct Outer<T>(Inner<T>) where a::Inner<T>: Debug;
+   |                               ++++++++++++++++++++++++
+
+error[E0277]: the trait bound `T: c::Trait` is not satisfied
+  --> $DIR/derive-macro-missing-bounds.rs:41:21
+   |
+LL |     #[derive(Debug)]
+   |              ----- in this derive macro expansion
+LL |     struct Outer<T>(Inner<T>);
+   |                     ^^^^^^^^ the trait `c::Trait` is not implemented for `T`
+   |
+note: required because of the requirements on the impl of `Debug` for `c::Inner<T>`
+  --> $DIR/derive-macro-missing-bounds.rs:34:28
+   |
+LL |     impl<T: Debug + Trait> Debug for Inner<T> {
+   |                            ^^^^^     ^^^^^^^^
+   = note: 1 redundant requirement hidden
+   = note: required because of the requirements on the impl of `Debug` for `&c::Inner<T>`
+   = note: required for the cast to the object type `dyn Debug`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider restricting type parameter `T`
+   |
+LL |     struct Outer<T: c::Trait>(Inner<T>);
+   |                   ++++++++++
+
+error[E0277]: the trait bound `T: d::Trait` is not satisfied
+  --> $DIR/derive-macro-missing-bounds.rs:56:21
+   |
+LL |     #[derive(Debug)]
+   |              ----- in this derive macro expansion
+LL |     struct Outer<T>(Inner<T>);
+   |                     ^^^^^^^^ the trait `d::Trait` is not implemented for `T`
+   |
+note: required because of the requirements on the impl of `Debug` for `d::Inner<T>`
+  --> $DIR/derive-macro-missing-bounds.rs:49:13
+   |
+LL |     impl<T> Debug for Inner<T> where T: Debug, T: Trait {
+   |             ^^^^^     ^^^^^^^^
+   = note: 1 redundant requirement hidden
+   = note: required because of the requirements on the impl of `Debug` for `&d::Inner<T>`
+   = note: required for the cast to the object type `dyn Debug`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider restricting type parameter `T`
+   |
+LL |     struct Outer<T: d::Trait>(Inner<T>);
+   |                   ++++++++++
+
+error[E0277]: the trait bound `T: e::Trait` is not satisfied
+  --> $DIR/derive-macro-missing-bounds.rs:71:21
+   |
+LL |     #[derive(Debug)]
+   |              ----- in this derive macro expansion
+LL |     struct Outer<T>(Inner<T>);
+   |                     ^^^^^^^^ the trait `e::Trait` is not implemented for `T`
+   |
+note: required because of the requirements on the impl of `Debug` for `e::Inner<T>`
+  --> $DIR/derive-macro-missing-bounds.rs:64:13
+   |
+LL |     impl<T> Debug for Inner<T> where T: Debug + Trait {
+   |             ^^^^^     ^^^^^^^^
+   = note: 1 redundant requirement hidden
+   = note: required because of the requirements on the impl of `Debug` for `&e::Inner<T>`
+   = note: required for the cast to the object type `dyn Debug`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider restricting type parameter `T`
+   |
+LL |     struct Outer<T: e::Trait>(Inner<T>);
+   |                   ++++++++++
+
+error[E0277]: the trait bound `T: f::Trait` is not satisfied
+  --> $DIR/derive-macro-missing-bounds.rs:86:21
+   |
+LL |     #[derive(Debug)]
+   |              ----- in this derive macro expansion
+LL |     struct Outer<T>(Inner<T>);
+   |                     ^^^^^^^^ the trait `f::Trait` is not implemented for `T`
+   |
+note: required because of the requirements on the impl of `Debug` for `f::Inner<T>`
+  --> $DIR/derive-macro-missing-bounds.rs:79:20
+   |
+LL |     impl<T: Debug> Debug for Inner<T> where T: Trait {
+   |                    ^^^^^     ^^^^^^^^
+   = note: 1 redundant requirement hidden
+   = note: required because of the requirements on the impl of `Debug` for `&f::Inner<T>`
+   = note: required for the cast to the object type `dyn Debug`
+   = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info)
+help: consider restricting type parameter `T`
+   |
+LL |     struct Outer<T: f::Trait>(Inner<T>);
+   |                   ++++++++++
+
+error: aborting due to 5 previous errors
+
+For more information about this error, try `rustc --explain E0277`.