Rollup merge of #115924 - compiler-errors:non-exhaustive-1-zst, r=RalfJung

Don't complain on a single non-exhaustive 1-ZST

r? RalfJung, though you mentioned being busy, so feel free to reassign.

This doesn't actually attempt to make the diagnostic better, so when we have two non-exhaustive 1-ZSTs in a struct, we still just point to one. 🤷

Fixes #115922

2 files changed, 81 insertions, 1 deletions

diff --git a/tests/ui/repr/repr-transparent-non-exhaustive.rs b/tests/ui/repr/repr-transparent-non-exhaustive.rs
index 506f1dcf3fc..84dd3f49239 100644
--- a/tests/ui/repr/repr-transparent-non-exhaustive.rs
+++ b/tests/ui/repr/repr-transparent-non-exhaustive.rs
@@ -93,4 +93,44 @@ pub struct T16(Sized, ExternalIndirection<NonExhaustiveVariant>);
 //~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
 //~| WARN this was previously accepted by the compiler
 
+#[repr(transparent)]
+pub struct T17(NonExhaustive, Sized);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T18(NonExhaustive, NonExhaustive);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T19(NonExhaustive, Private);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T19Flipped(Private, NonExhaustive);
+//~^ ERROR zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+//~| WARN this was previously accepted by the compiler
+
+#[repr(transparent)]
+pub struct T20(NonExhaustive);
+// Okay, since it's the only field.
+
+#[repr(transparent)]
+pub struct T21(NonExhaustive, InternalNonExhaustive);
+// Okay, since there's only 1 foreign non-exhaustive type.
+
+#[repr(transparent)]
+pub struct T21Flipped(InternalNonExhaustive, NonExhaustive);
+// Okay, since there's only 1 foreign non-exhaustive type.
+
+#[repr(transparent)]
+pub struct T22(NonExhaustive, InternalPrivate);
+// Okay, since there's only 1 foreign non-exhaustive type.
+
+#[repr(transparent)]
+pub struct T22Flipped(InternalPrivate, NonExhaustive);
+// Okay, since there's only 1 foreign non-exhaustive type.
+
 fn main() {}
diff --git a/tests/ui/repr/repr-transparent-non-exhaustive.stderr b/tests/ui/repr/repr-transparent-non-exhaustive.stderr
index 16edf59c7cc..808b9bc986d 100644
--- a/tests/ui/repr/repr-transparent-non-exhaustive.stderr
+++ b/tests/ui/repr/repr-transparent-non-exhaustive.stderr
@@ -123,5 +123,45 @@ LL | pub struct T16(Sized, ExternalIndirection<NonExhaustiveVariant>);
    = note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
    = note: this enum contains `NonExhaustiveVariant`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
 
-error: aborting due to 12 previous errors
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:97:16
+   |
+LL | pub struct T17(NonExhaustive, Sized);
+   |                ^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `NonExhaustive`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:102:31
+   |
+LL | pub struct T18(NonExhaustive, NonExhaustive);
+   |                               ^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `NonExhaustive`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:107:31
+   |
+LL | pub struct T19(NonExhaustive, Private);
+   |                               ^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `Private`, which contains private fields, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: zero-sized fields in `repr(transparent)` cannot contain external non-exhaustive types
+  --> $DIR/repr-transparent-non-exhaustive.rs:112:32
+   |
+LL | pub struct T19Flipped(Private, NonExhaustive);
+   |                                ^^^^^^^^^^^^^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
+   = note: this struct contains `NonExhaustive`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
+
+error: aborting due to 16 previous errors