Update rust toolchain to nightly-2023-09-19 (rust-lang#2778)

Co-authored-by: Remi Delmas <[email protected]>

Author: remi-delmas-3000

kani-compiler/src/kani_middle/reachability.rs

@@ -457,11 +457,9 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MonoItemsFnCollector<'a, 'tcx> {
                 match self.tcx.const_eval_resolve(ParamEnv::reveal_all(), un_eval, None) {
                     // The `monomorphize` call should have evaluated that constant already.
                     Ok(const_val) => const_val,
-                    Err(ErrorHandled::TooGeneric) => span_bug!(
-                        self.body.source_info(location).span,
-                        "Unexpected polymorphic constant: {:?}",
-                        literal
-                    ),
+                    Err(ErrorHandled::TooGeneric(span)) => {
+                        span_bug!(span, "Unexpected polymorphic constant: {:?}", literal)
+                    }
                     Err(error) => {
                         warn!(?error, "Error already reported");
                         return;

rust-toolchain.toml

@@ -2,5 +2,5 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 
 [toolchain]
-channel = "nightly-2023-09-18"
+channel = "nightly-2023-09-19"
 components = ["llvm-tools-preview", "rustc-dev", "rust-src", "rustfmt"]