Update MSRV to 1.90.0 (#12167)

* Update MSRV to 1.90.0

Coupled with last week's release of 1.92.0.

prtest:full

* Fix some warnings

* Fix another warning

Author: alexcrichton

.github/actions/install-rust/action.yml

@@ -32,7 +32,7 @@ runs:
         elif [ "${{ inputs.toolchain }}" = "msrv" ]; then
           echo "version=1.$msrv.0" >> "$GITHUB_OUTPUT"
         elif [ "${{ inputs.toolchain }}" = "wasmtime-ci-pinned-nightly" ]; then
-          echo "version=nightly-2025-11-25" >> "$GITHUB_OUTPUT"
+          echo "version=nightly-2025-12-15" >> "$GITHUB_OUTPUT"
         else
           echo "version=${{ inputs.toolchain }}" >> "$GITHUB_OUTPUT"
         fi

Cargo.toml

@@ -189,7 +189,7 @@ authors = ["The Wasmtime Project Developers"]
 edition = "2024"
 # Wasmtime's current policy is that this number can be no larger than the
 # current stable release of Rust minus 2.
-rust-version = "1.89.0"
+rust-version = "1.90.0"
 
 [workspace.lints.rust]
 # Turn on some lints which are otherwise allow-by-default in rustc.

crates/wasmtime/src/runtime/vm/libcalls.rs

@@ -115,6 +115,7 @@ pub mod raw {
                 // with conversion of the return value in the face of traps.
                 #[allow(improper_ctypes_definitions, reason = "__m128i known not FFI-safe")]
                 #[allow(unused_variables, reason = "macro-generated")]
+                #[allow(unreachable_code, reason = "some types uninhabited on some platforms")]
                 pub unsafe extern "C" fn $name(
                     vmctx: NonNull<VMContext>,
                     $( $pname : libcall!(@ty $param), )*

crates/wasmtime/src/runtime/vm/traphandlers.rs

@@ -181,6 +181,7 @@ macro_rules! host_result_no_catch {
         $(
             impl HostResult for $t {
                 type Abi = $t;
+                #[allow(unreachable_code, reason = "some types uninhabited on some platforms")]
                 fn maybe_catch_unwind(
                     store: &mut dyn VMStore,
                     f: impl FnOnce(&mut dyn VMStore) -> $t,

src/bin/wasmtime.rs

@@ -167,6 +167,7 @@ impl CompletionCommand {
     }
 }
 
+#[allow(unreachable_code, reason = "empty enum with all features disabled")]
 fn main() -> Result<()> {
     return Wasmtime::parse().execute();
 }