Rollup merge of #110791 - compiler-errors:negative-bounds, r=oli-obk

Implement negative bounds for internal testing purposes

Implements partial support the `!` negative polarity on trait bounds. This is incomplete, but should allow us to at least be able to play with the feature.

Not even gonna consider them as a public-facing feature, but I'm implementing them because would've been nice to have in UI tests, for example in #110671.

13 files changed, 241 insertions, 50 deletions

diff --git a/tests/ui/feature-gates/feature-gate-negative_bounds.rs b/tests/ui/feature-gates/feature-gate-negative_bounds.rs
new file mode 100644
index 00000000000..533cb0ce5bc
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-negative_bounds.rs
@@ -0,0 +1,4 @@
+fn test<T: !Copy>() {}
+//~^ ERROR negative bounds are not supported
+
+fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-negative_bounds.stderr b/tests/ui/feature-gates/feature-gate-negative_bounds.stderr
new file mode 100644
index 00000000000..ae010fdf3f8
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-negative_bounds.stderr
@@ -0,0 +1,8 @@
+error: negative bounds are not supported
+  --> $DIR/feature-gate-negative_bounds.rs:1:12
+   |
+LL | fn test<T: !Copy>() {}
+   |            ^
+
+error: aborting due to previous error
+
diff --git a/tests/ui/issues/issue-58857.stderr b/tests/ui/issues/issue-58857.stderr
index e2acec47e5a..6aef35f0bb9 100644
--- a/tests/ui/issues/issue-58857.stderr
+++ b/tests/ui/issues/issue-58857.stderr
@@ -1,8 +1,8 @@
 error: negative bounds are not supported
-  --> $DIR/issue-58857.rs:4:7
+  --> $DIR/issue-58857.rs:4:9
    |
 LL | impl<A: !Valid> Conj<A>{}
-   |       ^^^^^^^^ negative bounds are not supported
+   |         ^
 
 error: aborting due to previous error
 
diff --git a/tests/ui/parser/issues/issue-33418.fixed b/tests/ui/parser/issues/issue-33418.fixed
deleted file mode 100644
index ed885ae1435..00000000000
--- a/tests/ui/parser/issues/issue-33418.fixed
+++ /dev/null
@@ -1,19 +0,0 @@
-// run-rustfix
-
-trait Tr {}
-//~^ ERROR negative bounds are not supported
-trait Tr2: SuperA {}
-//~^ ERROR negative bounds are not supported
-trait Tr3: SuperB {}
-//~^ ERROR negative bounds are not supported
-trait Tr4: SuperB + SuperD {}
-//~^ ERROR negative bounds are not supported
-trait Tr5 {}
-//~^ ERROR negative bounds are not supported
-
-trait SuperA {}
-trait SuperB {}
-trait SuperC {}
-trait SuperD {}
-
-fn main() {}
diff --git a/tests/ui/parser/issues/issue-33418.rs b/tests/ui/parser/issues/issue-33418.rs
index 9934284abfb..4ebd5871e53 100644
--- a/tests/ui/parser/issues/issue-33418.rs
+++ b/tests/ui/parser/issues/issue-33418.rs
@@ -1,5 +1,3 @@
-// run-rustfix
-
 trait Tr: !SuperA {}
 //~^ ERROR negative bounds are not supported
 trait Tr2: SuperA + !SuperB {}
@@ -7,10 +5,12 @@ trait Tr2: SuperA + !SuperB {}
 trait Tr3: !SuperA + SuperB {}
 //~^ ERROR negative bounds are not supported
 trait Tr4: !SuperA + SuperB
-    + !SuperC + SuperD {}
+//~^ ERROR negative bounds are not supported
++ !SuperC + SuperD {}
 //~^ ERROR negative bounds are not supported
 trait Tr5: !SuperA
-    + !SuperB {}
+//~^ ERROR negative bounds are not supported
++ !SuperB {}
 //~^ ERROR negative bounds are not supported
 
 trait SuperA {}
diff --git a/tests/ui/parser/issues/issue-33418.stderr b/tests/ui/parser/issues/issue-33418.stderr
index 9a8733e8929..b111bcfd240 100644
--- a/tests/ui/parser/issues/issue-33418.stderr
+++ b/tests/ui/parser/issues/issue-33418.stderr
@@ -1,36 +1,44 @@
 error: negative bounds are not supported
-  --> $DIR/issue-33418.rs:3:9
+  --> $DIR/issue-33418.rs:1:11
    |
 LL | trait Tr: !SuperA {}
-   |         ^^^^^^^^^ negative bounds are not supported
+   |           ^
 
 error: negative bounds are not supported
-  --> $DIR/issue-33418.rs:5:19
+  --> $DIR/issue-33418.rs:3:21
    |
 LL | trait Tr2: SuperA + !SuperB {}
-   |                   ^^^^^^^^^ negative bounds are not supported
+   |                     ^
 
 error: negative bounds are not supported
-  --> $DIR/issue-33418.rs:7:10
+  --> $DIR/issue-33418.rs:5:12
    |
 LL | trait Tr3: !SuperA + SuperB {}
-   |          ^^^^^^^^^ negative bounds are not supported
+   |            ^
 
 error: negative bounds are not supported
-  --> $DIR/issue-33418.rs:9:10
+  --> $DIR/issue-33418.rs:7:12
    |
 LL | trait Tr4: !SuperA + SuperB
-   |          ^^^^^^^^^
-LL |     + !SuperC + SuperD {}
-   |     ^^^^^^^^^ negative bounds are not supported
+   |            ^
 
 error: negative bounds are not supported
-  --> $DIR/issue-33418.rs:12:10
+  --> $DIR/issue-33418.rs:9:3
+   |
+LL | + !SuperC + SuperD {}
+   |   ^
+
+error: negative bounds are not supported
+  --> $DIR/issue-33418.rs:11:12
    |
 LL | trait Tr5: !SuperA
-   |          ^^^^^^^^^
-LL |     + !SuperB {}
-   |     ^^^^^^^^^ negative bounds are not supported
+   |            ^
+
+error: negative bounds are not supported
+  --> $DIR/issue-33418.rs:13:3
+   |
+LL | + !SuperB {}
+   |   ^
 
-error: aborting due to 5 previous errors
+error: aborting due to 7 previous errors
 
diff --git a/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.fixed b/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.fixed
index 95019b27869..2c42f973174 100644
--- a/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.fixed
+++ b/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.fixed
@@ -6,9 +6,12 @@
 
 fn main() {}
 
-pub fn f1<T>() {}
+pub fn f1<T: 'static>() {}
 //~^ ERROR negative bounds are not supported
-pub fn f2<'a, T: Ord>() {}
+//~| ERROR `!` may only modify trait bounds, not lifetime bound
+pub fn f2<'a, T: Ord + 'a>() {}
 //~^ ERROR negative bounds are not supported
-pub fn f3<'a, T: Ord>() {}
+//~| ERROR `!` may only modify trait bounds, not lifetime bound
+pub fn f3<'a, T: 'a + Ord>() {}
 //~^ ERROR negative bounds are not supported
+//~| ERROR `!` may only modify trait bounds, not lifetime bound
diff --git a/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.rs b/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.rs
index 82f54f8faa9..e510efaae5b 100644
--- a/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.rs
+++ b/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.rs
@@ -8,7 +8,10 @@ fn main() {}
 
 pub fn f1<T: !'static>() {}
 //~^ ERROR negative bounds are not supported
+//~| ERROR `!` may only modify trait bounds, not lifetime bound
 pub fn f2<'a, T: Ord + !'a>() {}
 //~^ ERROR negative bounds are not supported
+//~| ERROR `!` may only modify trait bounds, not lifetime bound
 pub fn f3<'a, T: !'a + Ord>() {}
 //~^ ERROR negative bounds are not supported
+//~| ERROR `!` may only modify trait bounds, not lifetime bound
diff --git a/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.stderr b/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.stderr
index a4a422948ac..91fe02db3a6 100644
--- a/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.stderr
+++ b/tests/ui/parser/issues/issue-67146-negative-outlives-bound-syntactic-fail.stderr
@@ -1,20 +1,38 @@
+error: `!` may only modify trait bounds, not lifetime bounds
+  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:9:14
+   |
+LL | pub fn f1<T: !'static>() {}
+   |              ^
+
+error: `!` may only modify trait bounds, not lifetime bounds
+  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:12:24
+   |
+LL | pub fn f2<'a, T: Ord + !'a>() {}
+   |                        ^
+
+error: `!` may only modify trait bounds, not lifetime bounds
+  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:15:18
+   |
+LL | pub fn f3<'a, T: !'a + Ord>() {}
+   |                  ^
+
 error: negative bounds are not supported
-  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:9:12
+  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:9:14
    |
 LL | pub fn f1<T: !'static>() {}
-   |            ^^^^^^^^^^ negative bounds are not supported
+   |              ^
 
 error: negative bounds are not supported
-  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:11:22
+  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:12:24
    |
 LL | pub fn f2<'a, T: Ord + !'a>() {}
-   |                      ^^^^^ negative bounds are not supported
+   |                        ^
 
 error: negative bounds are not supported
-  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:13:16
+  --> $DIR/issue-67146-negative-outlives-bound-syntactic-fail.rs:15:18
    |
 LL | pub fn f3<'a, T: !'a + Ord>() {}
-   |                ^^^^^ negative bounds are not supported
+   |                  ^
 
-error: aborting due to 3 previous errors
+error: aborting due to 6 previous errors
 
diff --git a/tests/ui/traits/negative-bounds/associated-constraints.rs b/tests/ui/traits/negative-bounds/associated-constraints.rs
new file mode 100644
index 00000000000..bc1a0ef1708
--- /dev/null
+++ b/tests/ui/traits/negative-bounds/associated-constraints.rs
@@ -0,0 +1,20 @@
+#![feature(negative_bounds, associated_type_bounds)]
+//~^ WARN the feature `negative_bounds` is incomplete and may not be safe to use and/or cause compiler crashes
+
+trait Trait {
+    type Assoc;
+}
+
+fn test<T: !Trait<Assoc = i32>>() {}
+//~^ ERROR associated type constraints not allowed on negative bounds
+
+fn test2<T>() where T: !Trait<Assoc = i32> {}
+//~^ ERROR associated type constraints not allowed on negative bounds
+
+fn test3<T: !Trait<Assoc: Send>>() {}
+//~^ ERROR associated type constraints not allowed on negative bounds
+
+fn test4<T>() where T: !Trait<Assoc: Send> {}
+//~^ ERROR associated type constraints not allowed on negative bounds
+
+fn main() {}
diff --git a/tests/ui/traits/negative-bounds/associated-constraints.stderr b/tests/ui/traits/negative-bounds/associated-constraints.stderr
new file mode 100644
index 00000000000..335ac7e5ad9
--- /dev/null
+++ b/tests/ui/traits/negative-bounds/associated-constraints.stderr
@@ -0,0 +1,34 @@
+error: associated type constraints not allowed on negative bounds
+  --> $DIR/associated-constraints.rs:8:19
+   |
+LL | fn test<T: !Trait<Assoc = i32>>() {}
+   |                   ^^^^^^^^^^^
+
+error: associated type constraints not allowed on negative bounds
+  --> $DIR/associated-constraints.rs:11:31
+   |
+LL | fn test2<T>() where T: !Trait<Assoc = i32> {}
+   |                               ^^^^^^^^^^^
+
+error: associated type constraints not allowed on negative bounds
+  --> $DIR/associated-constraints.rs:14:20
+   |
+LL | fn test3<T: !Trait<Assoc: Send>>() {}
+   |                    ^^^^^^^^^^^
+
+error: associated type constraints not allowed on negative bounds
+  --> $DIR/associated-constraints.rs:17:31
+   |
+LL | fn test4<T>() where T: !Trait<Assoc: Send> {}
+   |                               ^^^^^^^^^^^
+
+warning: the feature `negative_bounds` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/associated-constraints.rs:1:12
+   |
+LL | #![feature(negative_bounds, associated_type_bounds)]
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+
+error: aborting due to 4 previous errors; 1 warning emitted
+
diff --git a/tests/ui/traits/negative-bounds/simple.rs b/tests/ui/traits/negative-bounds/simple.rs
new file mode 100644
index 00000000000..f6d1d5169c4
--- /dev/null
+++ b/tests/ui/traits/negative-bounds/simple.rs
@@ -0,0 +1,42 @@
+#![feature(negative_bounds, negative_impls)]
+//~^ WARN the feature `negative_bounds` is incomplete and may not be safe to use and/or cause compiler crashes
+
+fn not_copy<T: !Copy>() {}
+
+fn neg_param_env<T: !Copy>() {
+    not_copy::<T>();
+}
+
+fn pos_param_env<T: Copy>() {
+    not_copy::<T>();
+    //~^ ERROR the trait bound `T: !Copy` is not satisfied
+}
+
+fn unknown<T>() {
+    not_copy::<T>();
+    //~^ ERROR the trait bound `T: !Copy` is not satisfied
+}
+
+struct NotCopyable;
+impl !Copy for NotCopyable {}
+
+fn neg_impl() {
+    not_copy::<NotCopyable>();
+}
+
+#[derive(Copy, Clone)]
+struct Copyable;
+
+fn pos_impl() {
+    not_copy::<Copyable>();
+    //~^ ERROR the trait bound `Copyable: !Copy` is not satisfied
+}
+
+struct NotNecessarilyCopyable;
+
+fn unknown_impl() {
+    not_copy::<NotNecessarilyCopyable>();
+    //~^ ERROR the trait bound `NotNecessarilyCopyable: !Copy` is not satisfied
+}
+
+fn main() {}
diff --git a/tests/ui/traits/negative-bounds/simple.stderr b/tests/ui/traits/negative-bounds/simple.stderr
new file mode 100644
index 00000000000..a3cab41a2ce
--- /dev/null
+++ b/tests/ui/traits/negative-bounds/simple.stderr
@@ -0,0 +1,70 @@
+warning: the feature `negative_bounds` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/simple.rs:1:12
+   |
+LL | #![feature(negative_bounds, negative_impls)]
+   |            ^^^^^^^^^^^^^^^
+   |
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0277]: the trait bound `T: !Copy` is not satisfied
+  --> $DIR/simple.rs:11:16
+   |
+LL |     not_copy::<T>();
+   |                ^ the trait `!Copy` is not implemented for `T`
+   |
+note: required by a bound in `not_copy`
+  --> $DIR/simple.rs:4:16
+   |
+LL | fn not_copy<T: !Copy>() {}
+   |                ^^^^^ required by this bound in `not_copy`
+
+error[E0277]: the trait bound `T: !Copy` is not satisfied
+  --> $DIR/simple.rs:16:16
+   |
+LL |     not_copy::<T>();
+   |                ^ the trait `!Copy` is not implemented for `T`
+   |
+note: required by a bound in `not_copy`
+  --> $DIR/simple.rs:4:16
+   |
+LL | fn not_copy<T: !Copy>() {}
+   |                ^^^^^ required by this bound in `not_copy`
+
+error[E0277]: the trait bound `Copyable: !Copy` is not satisfied
+  --> $DIR/simple.rs:31:16
+   |
+LL |     not_copy::<Copyable>();
+   |                ^^^^^^^^ the trait `!Copy` is not implemented for `Copyable`
+   |
+   = help: the trait `Copy` is implemented for `Copyable`
+note: required by a bound in `not_copy`
+  --> $DIR/simple.rs:4:16
+   |
+LL | fn not_copy<T: !Copy>() {}
+   |                ^^^^^ required by this bound in `not_copy`
+help: consider annotating `Copyable` with `#[derive(Copy)]`
+   |
+LL + #[derive(Copy)]
+LL | struct Copyable;
+   |
+
+error[E0277]: the trait bound `NotNecessarilyCopyable: !Copy` is not satisfied
+  --> $DIR/simple.rs:38:16
+   |
+LL |     not_copy::<NotNecessarilyCopyable>();
+   |                ^^^^^^^^^^^^^^^^^^^^^^ the trait `!Copy` is not implemented for `NotNecessarilyCopyable`
+   |
+note: required by a bound in `not_copy`
+  --> $DIR/simple.rs:4:16
+   |
+LL | fn not_copy<T: !Copy>() {}
+   |                ^^^^^ required by this bound in `not_copy`
+help: consider annotating `NotNecessarilyCopyable` with `#[derive(Copy)]`
+   |
+LL + #[derive(Copy)]
+LL | struct NotNecessarilyCopyable;
+   |
+
+error: aborting due to 4 previous errors; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0277`.