convert assertion on rvalue::threadlocalref to delay bug

compiler/rustc_mir/src/transform/check_consts/validation.rs

@@ -356,10 +356,9 @@ impl Validator<'mir, 'tcx> {
     }
 
     fn check_static(&mut self, def_id: DefId, span: Span) {
-        assert!(
-            !self.tcx.is_thread_local_static(def_id),
-            "tls access is checked in `Rvalue::ThreadLocalRef"
-        );
+        if self.tcx.is_thread_local_static(def_id) {
+            self.tcx.sess.delay_span_bug(span, "tls access is checked in `Rvalue::ThreadLocalRef");
+        }
         self.check_op_spanned(ops::StaticAccess, span)
     }
 

src/test/ui/thread-local-static.rs

@@ -0,0 +1,16 @@
+// edition:2018
+
+#![feature(thread_local)]
+#![feature(const_swap)]
+#[thread_local]
+static mut STATIC_VAR_2: [u32; 8] = [4; 8];
+const fn g(x: &mut [u32; 8]) {
+    //~^ ERROR mutable references are not allowed
+    std::mem::swap(x, &mut STATIC_VAR_2)
+    //~^ ERROR thread-local statics cannot be accessed
+    //~| ERROR mutable references are not allowed
+    //~| ERROR use of mutable static is unsafe
+    //~| constant functions cannot refer to statics
+}
+
+fn main() {}

src/test/ui/thread-local-static.stderr

@@ -0,0 +1,44 @@
+error[E0658]: mutable references are not allowed in constant functions
+  --> $DIR/thread-local-static.rs:7:12
+   |
+LL | const fn g(x: &mut [u32; 8]) {
+   |            ^
+   |
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0625]: thread-local statics cannot be accessed at compile-time
+  --> $DIR/thread-local-static.rs:9:28
+   |
+LL |     std::mem::swap(x, &mut STATIC_VAR_2)
+   |                            ^^^^^^^^^^^^
+
+error[E0013]: constant functions cannot refer to statics
+  --> $DIR/thread-local-static.rs:9:28
+   |
+LL |     std::mem::swap(x, &mut STATIC_VAR_2)
+   |                            ^^^^^^^^^^^^
+   |
+   = help: consider extracting the value of the `static` to a `const`, and referring to that
+
+error[E0658]: mutable references are not allowed in constant functions
+  --> $DIR/thread-local-static.rs:9:23
+   |
+LL |     std::mem::swap(x, &mut STATIC_VAR_2)
+   |                       ^^^^^^^^^^^^^^^^^
+   |
+   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
+   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+
+error[E0133]: use of mutable static is unsafe and requires unsafe function or block
+  --> $DIR/thread-local-static.rs:9:23
+   |
+LL |     std::mem::swap(x, &mut STATIC_VAR_2)
+   |                       ^^^^^^^^^^^^^^^^^ use of mutable static
+   |
+   = note: mutable statics can be mutated by multiple threads: aliasing violations or data races will cause undefined behavior
+
+error: aborting due to 5 previous errors
+
+Some errors have detailed explanations: E0013, E0133, E0658.
+For more information about an error, try `rustc --explain E0013`.