Auto merge of #83308 - Dylan-DPC:rollup-p2j6sy8, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - #79986 (Only build help popup when it's really needed)
 - #82570 (Add `as_str` method for split whitespace str iterators)
 - #83244 (Fix overflowing length in Vec<ZST> to VecDeque)
 - #83254 (Include output stream in `panic!()` documentation)
 - #83269 (Revert the second deprecation of collections::Bound)
 - #83277 (Mark early otherwise optimization unsound)
 - #83285 (Update LLVM to bring in SIMD updates for WebAssembly)
 - #83297 (Do not ICE on ty::Error as an error must already have been reported)

Failed merges:

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

6 files changed, 69 insertions, 2 deletions

diff --git a/src/test/mir-opt/early_otherwise_branch.rs b/src/test/mir-opt/early_otherwise_branch.rs
index 548213ab83c..b2caf7d7b8f 100644
--- a/src/test/mir-opt/early_otherwise_branch.rs
+++ b/src/test/mir-opt/early_otherwise_branch.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4
+// compile-flags: -Z mir-opt-level=4 -Z unsound-mir-opts
 // EMIT_MIR early_otherwise_branch.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>) -> u32 {
     match (x, y) {
diff --git a/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs b/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs
index aa304f747f7..8527c01d756 100644
--- a/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs
+++ b/src/test/mir-opt/early_otherwise_branch_3_element_tuple.rs
@@ -1,4 +1,4 @@
-// compile-flags: -Z mir-opt-level=4
+// compile-flags: -Z mir-opt-level=4 -Z unsound-mir-opts
 
 // EMIT_MIR early_otherwise_branch_3_element_tuple.opt1.EarlyOtherwiseBranch.diff
 fn opt1(x: Option<u32>, y: Option<u32>, z: Option<u32>) -> u32 {
diff --git a/src/test/ui/const-generics/type_mismatch.rs b/src/test/ui/const-generics/type_mismatch.rs
new file mode 100644
index 00000000000..4a7534e3713
--- /dev/null
+++ b/src/test/ui/const-generics/type_mismatch.rs
@@ -0,0 +1,9 @@
+fn foo<const N: usize>() -> [u8; N] {
+    bar::<N>() //~ ERROR mismatched types
+}
+
+fn bar<const N: u8>() -> [u8; N] {}
+//~^ ERROR mismatched types
+//~| ERROR mismatched types
+
+fn main() {}
diff --git a/src/test/ui/const-generics/type_mismatch.stderr b/src/test/ui/const-generics/type_mismatch.stderr
new file mode 100644
index 00000000000..f5053e4c8c8
--- /dev/null
+++ b/src/test/ui/const-generics/type_mismatch.stderr
@@ -0,0 +1,23 @@
+error[E0308]: mismatched types
+  --> $DIR/type_mismatch.rs:2:11
+   |
+LL |     bar::<N>()
+   |           ^ expected `u8`, found `usize`
+
+error[E0308]: mismatched types
+  --> $DIR/type_mismatch.rs:5:31
+   |
+LL | fn bar<const N: u8>() -> [u8; N] {}
+   |                               ^ expected `usize`, found `u8`
+
+error[E0308]: mismatched types
+  --> $DIR/type_mismatch.rs:5:26
+   |
+LL | fn bar<const N: u8>() -> [u8; N] {}
+   |    ---                   ^^^^^^^ expected array `[u8; N]`, found `()`
+   |    |
+   |    implicitly returns `()` as its body has no tail or `return` expression
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/src/test/ui/const-generics/type_not_in_scope.rs b/src/test/ui/const-generics/type_not_in_scope.rs
new file mode 100644
index 00000000000..5933701808b
--- /dev/null
+++ b/src/test/ui/const-generics/type_not_in_scope.rs
@@ -0,0 +1,11 @@
+impl X {
+    //~^ ERROR cannot find type
+    fn getn<const N: usize>() -> [u8; N] {
+        getn::<N>()
+    }
+}
+fn getn<const N: cfg_attr>() -> [u8; N] {}
+//~^ ERROR expected type, found built-in attribute `cfg_attr`
+//~| ERROR mismatched types
+
+fn main() {}
diff --git a/src/test/ui/const-generics/type_not_in_scope.stderr b/src/test/ui/const-generics/type_not_in_scope.stderr
new file mode 100644
index 00000000000..16796acb3d2
--- /dev/null
+++ b/src/test/ui/const-generics/type_not_in_scope.stderr
@@ -0,0 +1,24 @@
+error[E0412]: cannot find type `X` in this scope
+  --> $DIR/type_not_in_scope.rs:1:6
+   |
+LL | impl X {
+   |      ^ not found in this scope
+
+error[E0573]: expected type, found built-in attribute `cfg_attr`
+  --> $DIR/type_not_in_scope.rs:7:18
+   |
+LL | fn getn<const N: cfg_attr>() -> [u8; N] {}
+   |                  ^^^^^^^^ not a type
+
+error[E0308]: mismatched types
+  --> $DIR/type_not_in_scope.rs:7:33
+   |
+LL | fn getn<const N: cfg_attr>() -> [u8; N] {}
+   |    ----                         ^^^^^^^ expected array `[u8; N]`, found `()`
+   |    |
+   |    implicitly returns `()` as its body has no tail or `return` expression
+
+error: aborting due to 3 previous errors
+
+Some errors have detailed explanations: E0308, E0412, E0573.
+For more information about an error, try `rustc --explain E0308`.