Warn for Rust 2024 compatibility

This adds warnings for Rust 2024 compatibility so that backtrace can be
used in std (which will be migrating to 2024) without actually changing
the edition here (due to MSRV). This should help prevent any regressions
until backtrace can move to Rust 2024 (1.85).

This bumps the MSRV to support `unsafe extern`.

This allows some lints that are relatively noisy and do not usually
prevent use in 2024.

These can all be removed when migrating to 2024 in the future.

Author: ehuss

.github/workflows/main.yml

@@ -256,7 +256,7 @@ jobs:
         with:
           submodules: true
       - name: Install Rust
-        run: rustup update 1.79.0 --no-self-update && rustup default 1.79.0
+        run: rustup update 1.82.0 --no-self-update && rustup default 1.82.0
       - run: cargo build
 
   miri:

Cargo.toml

@@ -14,7 +14,7 @@ autoexamples = true
 autotests = true
 edition = "2021"
 exclude = ["/ci/"]
-rust-version = "1.79.0"
+rust-version = "1.82.0"
 
 [workspace]
 members = ['crates/cpp_smoke_test', 'crates/as-if-std']

src/lib.rs

@@ -91,6 +91,11 @@
     feature(sgx_platform)
 )]
 #![warn(rust_2018_idioms)]
+#![warn(rust_2024_compatibility)]
+#![allow(
+    edition_2024_expr_fragment_specifier,
+    tail_expr_drop_order
+)]
 // When we're building as part of libstd, silence all warnings since they're
 // irrelevant as this crate is developed out-of-tree.
 #![cfg_attr(backtrace_in_libstd, allow(warnings))]