diff --git a/Cargo.toml b/Cargo.toml
index 8766245a2a..35ed0120d9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,7 +9,7 @@ categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 default-run = "wasmtime"
 
 [lib]
diff --git a/cranelift/Cargo.toml b/cranelift/Cargo.toml
index a63e619b6f..b1efe774ec 100644
--- a/cranelift/Cargo.toml
+++ b/cranelift/Cargo.toml
@@ -7,7 +7,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 documentation = "https://github.com/bytecodealliance/wasmtime/blob/main/cranelift/docs/index.md"
 repository = "https://github.com/bytecodealliance/wasmtime"
 publish = false
-edition = "2018"
+edition = "2021"
 
 [[bin]]
 name = "clif-util"
diff --git a/cranelift/bforest/Cargo.toml b/cranelift/bforest/Cargo.toml
index cbbee192f5..e5685d98f6 100644
--- a/cranelift/bforest/Cargo.toml
+++ b/cranelift/bforest/Cargo.toml
@@ -9,7 +9,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 categories = ["no-std"]
 readme = "README.md"
 keywords = ["btree", "forest", "set", "map"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-entity = { path = "../entity", version = "0.83.0", default-features = false }
diff --git a/cranelift/codegen/Cargo.toml b/cranelift/codegen/Cargo.toml
index cb6f352d5b..6956654064 100644
--- a/cranelift/codegen/Cargo.toml
+++ b/cranelift/codegen/Cargo.toml
@@ -10,7 +10,7 @@ categories = ["no-std"]
 readme = "README.md"
 keywords = ["compile", "compiler", "jit"]
 build = "build.rs"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen-shared = { path = "./shared", version = "0.83.0" }
diff --git a/cranelift/codegen/meta/Cargo.toml b/cranelift/codegen/meta/Cargo.toml
index a50b3ea7a5..8cc5138929 100644
--- a/cranelift/codegen/meta/Cargo.toml
+++ b/cranelift/codegen/meta/Cargo.toml
@@ -6,7 +6,7 @@ description = "Metaprogram for cranelift-codegen code generator library"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 # FIXME(rust-lang/cargo#9300): uncomment once that lands
 # [package.metadata.docs.rs]
diff --git a/cranelift/codegen/shared/Cargo.toml b/cranelift/codegen/shared/Cargo.toml
index d11c470b4a..1f10bccfaa 100644
--- a/cranelift/codegen/shared/Cargo.toml
+++ b/cranelift/codegen/shared/Cargo.toml
@@ -6,7 +6,7 @@ description = "For code shared between cranelift-codegen-meta and cranelift-code
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 # Since this is a shared dependency of several packages, please strive to keep this dependency-free
diff --git a/cranelift/entity/Cargo.toml b/cranelift/entity/Cargo.toml
index a9ee8e3ebf..8c3df0db10 100644
--- a/cranelift/entity/Cargo.toml
+++ b/cranelift/entity/Cargo.toml
@@ -9,7 +9,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 categories = ["no-std"]
 readme = "README.md"
 keywords = ["entity", "set", "map"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 serde = { version = "1.0.94", features = ["derive"], optional = true }
diff --git a/cranelift/filetests/Cargo.toml b/cranelift/filetests/Cargo.toml
index 2f843f6b7f..016b6377cd 100644
--- a/cranelift/filetests/Cargo.toml
+++ b/cranelift/filetests/Cargo.toml
@@ -7,7 +7,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 documentation = "https://docs.rs/cranelift-filetests"
 repository = "https://github.com/bytecodealliance/wasmtime"
 publish = false
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0", features = ["testing_hooks"] }
diff --git a/cranelift/frontend/Cargo.toml b/cranelift/frontend/Cargo.toml
index 04a329eb3f..e1c1fb7a06 100644
--- a/cranelift/frontend/Cargo.toml
+++ b/cranelift/frontend/Cargo.toml
@@ -8,7 +8,7 @@ documentation = "https://docs.rs/cranelift-frontend"
 categories = ["no-std"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0", default-features = false }
diff --git a/cranelift/fuzzgen/Cargo.toml b/cranelift/fuzzgen/Cargo.toml
index 4b1661c9d4..7eda017323 100644
--- a/cranelift/fuzzgen/Cargo.toml
+++ b/cranelift/fuzzgen/Cargo.toml
@@ -6,7 +6,7 @@ description = "Cranelift module generator"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 publish = false
 
 
diff --git a/cranelift/interpreter/Cargo.toml b/cranelift/interpreter/Cargo.toml
index fb73c8a59b..5c3e50d8e4 100644
--- a/cranelift/interpreter/Cargo.toml
+++ b/cranelift/interpreter/Cargo.toml
@@ -8,7 +8,7 @@ documentation = "https://docs.rs/cranelift-interpreter"
 categories = ["no-std"]
 license = "Apache-2.0 WITH LLVM-exception"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0" }
diff --git a/cranelift/isle/fuzz/Cargo.toml b/cranelift/isle/fuzz/Cargo.toml
index 52460851f8..656da46466 100644
--- a/cranelift/isle/fuzz/Cargo.toml
+++ b/cranelift/isle/fuzz/Cargo.toml
@@ -3,7 +3,7 @@ name = "isle-fuzz"
 version = "0.0.0"
 authors = ["Automatically generated"]
 publish = false
-edition = "2018"
+edition = "2021"
 
 [package.metadata]
 cargo-fuzz = true
diff --git a/cranelift/isle/isle/Cargo.toml b/cranelift/isle/isle/Cargo.toml
index c884180d1c..a1c45a9d4d 100644
--- a/cranelift/isle/isle/Cargo.toml
+++ b/cranelift/isle/isle/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 authors = ["The Cranelift Project Developers"]
 description = "ISLE: Instruction Selection and Lowering Expressions. A domain-specific language for instruction selection in Cranelift."
-edition = "2018"
+edition = "2021"
 license = "Apache-2.0 WITH LLVM-exception"
 name = "cranelift-isle"
 readme = "../README.md"
diff --git a/cranelift/isle/islec/Cargo.toml b/cranelift/isle/islec/Cargo.toml
index b29edacba3..cf834627ad 100644
--- a/cranelift/isle/islec/Cargo.toml
+++ b/cranelift/isle/islec/Cargo.toml
@@ -2,7 +2,7 @@
 name = "islec"
 version = "0.1.0"
 authors = ["The Cranelift Project Developers"]
-edition = "2018"
+edition = "2021"
 license = "Apache-2.0 WITH LLVM-exception"
 publish = false
 
diff --git a/cranelift/jit/Cargo.toml b/cranelift/jit/Cargo.toml
index 67ef9e2a60..aeb9443128 100644
--- a/cranelift/jit/Cargo.toml
+++ b/cranelift/jit/Cargo.toml
@@ -7,7 +7,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 documentation = "https://docs.rs/cranelift-jit"
 license = "Apache-2.0 WITH LLVM-exception"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-module = { path = "../module", version = "0.83.0" }
diff --git a/cranelift/module/Cargo.toml b/cranelift/module/Cargo.toml
index 2605f48044..97e0e95827 100644
--- a/cranelift/module/Cargo.toml
+++ b/cranelift/module/Cargo.toml
@@ -8,7 +8,7 @@ documentation = "https://docs.rs/cranelift-module"
 categories = ["no-std"]
 license = "Apache-2.0 WITH LLVM-exception"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0", default-features = false }
diff --git a/cranelift/native/Cargo.toml b/cranelift/native/Cargo.toml
index 99db7940b8..040146b62e 100644
--- a/cranelift/native/Cargo.toml
+++ b/cranelift/native/Cargo.toml
@@ -8,7 +8,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 categories = ["no-std"]
 license = "Apache-2.0 WITH LLVM-exception"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0", default-features = false }
diff --git a/cranelift/object/Cargo.toml b/cranelift/object/Cargo.toml
index f925dbe72c..6d2ca37ca7 100644
--- a/cranelift/object/Cargo.toml
+++ b/cranelift/object/Cargo.toml
@@ -7,7 +7,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 documentation = "https://docs.rs/cranelift-object"
 license = "Apache-2.0 WITH LLVM-exception"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-module = { path = "../module", version = "0.83.0" }
diff --git a/cranelift/preopt/Cargo.toml b/cranelift/preopt/Cargo.toml
index a779cbaa95..7b254094f9 100644
--- a/cranelift/preopt/Cargo.toml
+++ b/cranelift/preopt/Cargo.toml
@@ -9,7 +9,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 categories = ["no-std"]
 readme = "README.md"
 keywords = ["optimize", "compile", "compiler", "jit"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0", default-features = false }
diff --git a/cranelift/reader/Cargo.toml b/cranelift/reader/Cargo.toml
index 37a52b46a1..740128fe0e 100644
--- a/cranelift/reader/Cargo.toml
+++ b/cranelift/reader/Cargo.toml
@@ -7,7 +7,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 documentation = "https://docs.rs/cranelift-reader"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0" }
diff --git a/cranelift/serde/Cargo.toml b/cranelift/serde/Cargo.toml
index a71bd8b349..06300eca0b 100644
--- a/cranelift/serde/Cargo.toml
+++ b/cranelift/serde/Cargo.toml
@@ -7,7 +7,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 license = "Apache-2.0 WITH LLVM-exception"
 readme = "README.md"
 keywords = ["webassembly", "serde"]
-edition = "2018"
+edition = "2021"
 
 [[bin]]
 name = "clif-json"
diff --git a/cranelift/umbrella/Cargo.toml b/cranelift/umbrella/Cargo.toml
index 185fcf2f2a..c3cc8249d1 100644
--- a/cranelift/umbrella/Cargo.toml
+++ b/cranelift/umbrella/Cargo.toml
@@ -9,7 +9,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 categories = ["no-std"]
 readme = "README.md"
 keywords = ["compile", "compiler", "jit"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-codegen = { path = "../codegen", version = "0.83.0", default-features = false }
diff --git a/cranelift/wasm/Cargo.toml b/cranelift/wasm/Cargo.toml
index 959f88a5eb..c91f82e1d0 100644
--- a/cranelift/wasm/Cargo.toml
+++ b/cranelift/wasm/Cargo.toml
@@ -9,7 +9,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 categories = ["no-std", "wasm"]
 readme = "README.md"
 keywords = ["webassembly", "wasm"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 wasmparser = { version = "0.83.0", default-features = false }
diff --git a/crates/bench-api/Cargo.toml b/crates/bench-api/Cargo.toml
index fef31aa9c8..7393615612 100644
--- a/crates/bench-api/Cargo.toml
+++ b/crates/bench-api/Cargo.toml
@@ -6,7 +6,7 @@ description = "Exposes a benchmarking API for the Wasmtime runtime"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [lib]
diff --git a/crates/c-api/Cargo.toml b/crates/c-api/Cargo.toml
index ed11a4bdc7..99bb65ac59 100644
--- a/crates/c-api/Cargo.toml
+++ b/crates/c-api/Cargo.toml
@@ -6,7 +6,7 @@ description = "C API to expose the Wasmtime runtime"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [lib]
diff --git a/crates/c-api/macros/Cargo.toml b/crates/c-api/macros/Cargo.toml
index cc6e1cf0fb..f6eb6ec9df 100644
--- a/crates/c-api/macros/Cargo.toml
+++ b/crates/c-api/macros/Cargo.toml
@@ -2,7 +2,7 @@
 name = "wasmtime-c-api-macros"
 version = "0.19.0"
 authors = ["The Wasmtime Project Developers"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [lib]
diff --git a/crates/c-api/src/func.rs b/crates/c-api/src/func.rs
index 76ba0759c0..daf38bd5df 100644
--- a/crates/c-api/src/func.rs
+++ b/crates/c-api/src/func.rs
@@ -104,6 +104,7 @@ pub unsafe extern "C" fn wasm_func_new_with_env(
 ) -> Box<wasm_func_t> {
     let finalizer = crate::ForeignData { data, finalizer };
     create_function(store, ty, move |params, results| {
+        drop(&finalizer); // move entire finalizer into this closure
         callback(finalizer.data, params, results)
     })
 }
@@ -233,6 +234,8 @@ pub(crate) unsafe fn c_callback_to_rust_fn(
 ) -> impl Fn(Caller<'_, crate::StoreData>, &[Val], &mut [Val]) -> Result<(), Trap> {
     let foreign = crate::ForeignData { data, finalizer };
     move |mut caller, params, results| {
+        drop(&foreign); // move entire foreign into this closure
+
         // Convert `params/results` to `wasmtime_val_t`. Use the previous
         // storage in `hostcall_val_storage` to help avoid allocations all the
         // time.
@@ -295,6 +298,7 @@ pub(crate) unsafe fn c_unchecked_callback_to_rust_fn(
 ) -> impl Fn(Caller<'_, crate::StoreData>, *mut ValRaw) -> Result<(), Trap> {
     let foreign = crate::ForeignData { data, finalizer };
     move |caller, values| {
+        drop(&foreign); // move entire foreign into this closure
         let mut caller = wasmtime_caller_t { caller };
         match callback(foreign.data, &mut caller, values) {
             None => Ok(()),
diff --git a/crates/cache/Cargo.toml b/crates/cache/Cargo.toml
index e86e5653ad..1cc997b30e 100644
--- a/crates/cache/Cargo.toml
+++ b/crates/cache/Cargo.toml
@@ -6,7 +6,7 @@ description = "Support for automatic module caching with Wasmtime"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 documentation = "https://docs.rs/wasmtime-cache/"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 anyhow = "1.0"
diff --git a/crates/cache/src/worker.rs b/crates/cache/src/worker.rs
index 8ee5aa263c..d2264022b5 100644
--- a/crates/cache/src/worker.rs
+++ b/crates/cache/src/worker.rs
@@ -230,7 +230,6 @@ impl WorkerThread {
 
     #[cfg(target_os = "windows")]
     fn lower_thread_priority() {
-        use std::convert::TryInto;
         use winapi::um::processthreadsapi::{GetCurrentThread, SetThreadPriority};
         use winapi::um::winbase::THREAD_MODE_BACKGROUND_BEGIN;
 
diff --git a/crates/environ/Cargo.toml b/crates/environ/Cargo.toml
index 61baa9a257..2c9cad640e 100644
--- a/crates/environ/Cargo.toml
+++ b/crates/environ/Cargo.toml
@@ -8,7 +8,7 @@ repository = "https://github.com/bytecodealliance/wasmtime"
 documentation = "https://docs.rs/wasmtime-environ/"
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 anyhow = "1.0"
diff --git a/crates/fiber/Cargo.toml b/crates/fiber/Cargo.toml
index 60076fc7f1..5a3ca38412 100644
--- a/crates/fiber/Cargo.toml
+++ b/crates/fiber/Cargo.toml
@@ -5,7 +5,7 @@ authors = ["The Wasmtime Project Developers"]
 description = "Fiber support for Wasmtime"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
-edition = "2018"
+edition = "2021"
 
 # We link to some native code with symbols that don't change often, so let Cargo
 # know that we can't show up multiple times in a crate graph. If this is an
diff --git a/crates/fuzzing/Cargo.toml b/crates/fuzzing/Cargo.toml
index 06ed8f9b23..3c9881702a 100644
--- a/crates/fuzzing/Cargo.toml
+++ b/crates/fuzzing/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 authors = ["The Wasmtime Project Developers"]
 description = "Fuzzing infrastructure for Wasmtime"
-edition = "2018"
+edition = "2021"
 name = "wasmtime-fuzzing"
 publish = false
 version = "0.19.0"
diff --git a/crates/fuzzing/wasm-spec-interpreter/Cargo.toml b/crates/fuzzing/wasm-spec-interpreter/Cargo.toml
index bd37c83e6c..e9e3b746bd 100644
--- a/crates/fuzzing/wasm-spec-interpreter/Cargo.toml
+++ b/crates/fuzzing/wasm-spec-interpreter/Cargo.toml
@@ -4,7 +4,7 @@ description = "A Rust-to-OCaml wrapper for the WebAssembly specification interpr
 name = "wasm-spec-interpreter"
 version = "0.1.0"
 publish = false
-edition = "2018"
+edition = "2021"
 license = "Apache-2.0 WITH LLVM-exception"
 
 # Until https://gitlab.com/ocaml-rust/ocaml-boxroot/-/issues/1 is resolved and
diff --git a/crates/jit-debug/Cargo.toml b/crates/jit-debug/Cargo.toml
index cb4594c7b0..f1f4952982 100644
--- a/crates/jit-debug/Cargo.toml
+++ b/crates/jit-debug/Cargo.toml
@@ -8,7 +8,7 @@ categories = ["development-tools::debugging"]
 keywords = ["gdb", "jit"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 lazy_static = {version = "1.3.0", optional = true }
diff --git a/crates/jit/Cargo.toml b/crates/jit/Cargo.toml
index ae0f95ca47..a9022d3916 100644
--- a/crates/jit/Cargo.toml
+++ b/crates/jit/Cargo.toml
@@ -8,7 +8,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 wasmtime-environ = { path = "../environ", version = "=0.36.0" }
diff --git a/crates/misc/run-examples/Cargo.toml b/crates/misc/run-examples/Cargo.toml
index 76b6470ec1..01167683d6 100644
--- a/crates/misc/run-examples/Cargo.toml
+++ b/crates/misc/run-examples/Cargo.toml
@@ -2,7 +2,7 @@
 name = "run-examples"
 version = "0.19.0"
 authors = ["The Wasmtime Project Developers"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]
diff --git a/crates/runtime/Cargo.toml b/crates/runtime/Cargo.toml
index 54838fca40..00e7b94fd7 100644
--- a/crates/runtime/Cargo.toml
+++ b/crates/runtime/Cargo.toml
@@ -8,7 +8,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 wasmtime-environ = { path = "../environ", version = "=0.36.0" }
diff --git a/crates/test-programs/Cargo.toml b/crates/test-programs/Cargo.toml
index 432e63a418..5bd418f51d 100644
--- a/crates/test-programs/Cargo.toml
+++ b/crates/test-programs/Cargo.toml
@@ -3,7 +3,7 @@ name = "test-programs"
 version = "0.19.0"
 authors = ["The Wasmtime Project Developers"]
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 publish = false
 license = "Apache-2.0 WITH LLVM-exception"
 
diff --git a/crates/test-programs/wasi-tests/Cargo.toml b/crates/test-programs/wasi-tests/Cargo.toml
index c120f463bf..772d398fef 100644
--- a/crates/test-programs/wasi-tests/Cargo.toml
+++ b/crates/test-programs/wasi-tests/Cargo.toml
@@ -3,7 +3,7 @@ name = "wasi-tests"
 version = "0.19.0"
 authors = ["The Wasmtime Project Developers"]
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]
diff --git a/crates/types/Cargo.toml b/crates/types/Cargo.toml
index 89165e7936..5898c0cc4d 100644
--- a/crates/types/Cargo.toml
+++ b/crates/types/Cargo.toml
@@ -6,7 +6,7 @@ description = "WebAssembly type definitions for Cranelift"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 documentation = "https://docs.rs/wasmtime-types"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cranelift-entity = { path = "../../cranelift/entity", version = "0.83.0", features = ['enable-serde'] }
diff --git a/crates/wasi-common/Cargo.toml b/crates/wasi-common/Cargo.toml
index c8d641e714..b2f7e13740 100644
--- a/crates/wasi-common/Cargo.toml
+++ b/crates/wasi-common/Cargo.toml
@@ -8,7 +8,7 @@ categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 include = ["src/**/*", "WASI/phases/**/*", "README.md", "LICENSE", "build.rs"]
 build = "build.rs"
 
diff --git a/crates/wasi-common/cap-std-sync/Cargo.toml b/crates/wasi-common/cap-std-sync/Cargo.toml
index bd9eff831e..96053dcbc8 100644
--- a/crates/wasi-common/cap-std-sync/Cargo.toml
+++ b/crates/wasi-common/cap-std-sync/Cargo.toml
@@ -8,7 +8,7 @@ categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 include = ["src/**/*", "README.md", "LICENSE" ]
 
 [dependencies]
diff --git a/crates/wasi-common/tokio/Cargo.toml b/crates/wasi-common/tokio/Cargo.toml
index b904bd0c05..910dbced9b 100644
--- a/crates/wasi-common/tokio/Cargo.toml
+++ b/crates/wasi-common/tokio/Cargo.toml
@@ -7,7 +7,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
-edition = "2018"
+edition = "2021"
 include = ["src/**/*", "LICENSE" ]
 
 [dependencies]
diff --git a/crates/wasi-crypto/Cargo.toml b/crates/wasi-crypto/Cargo.toml
index 3151f2ec4c..7fed94356d 100644
--- a/crates/wasi-crypto/Cargo.toml
+++ b/crates/wasi-crypto/Cargo.toml
@@ -9,7 +9,7 @@ categories = ["wasm", "cryptography"]
 keywords = ["webassembly", "wasm", "crypto"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 anyhow = "1.0"
diff --git a/crates/wasi-nn/Cargo.toml b/crates/wasi-nn/Cargo.toml
index 91c773d91e..66fb5213fa 100644
--- a/crates/wasi-nn/Cargo.toml
+++ b/crates/wasi-nn/Cargo.toml
@@ -9,7 +9,7 @@ categories = ["wasm", "computer-vision"]
 keywords = ["webassembly", "wasm", "neural-network"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 # These dependencies are necessary for the witx-generation macros to work:
diff --git a/crates/wasi-nn/examples/classification-example/Cargo.toml b/crates/wasi-nn/examples/classification-example/Cargo.toml
index f74c4eab84..a2efe807b4 100644
--- a/crates/wasi-nn/examples/classification-example/Cargo.toml
+++ b/crates/wasi-nn/examples/classification-example/Cargo.toml
@@ -3,7 +3,7 @@ name = "wasi-nn-example"
 version = "0.19.0"
 authors = ["The Wasmtime Project Developers"]
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]
diff --git a/crates/wasi/Cargo.toml b/crates/wasi/Cargo.toml
index 2bf3eaa297..4a5f16fa86 100644
--- a/crates/wasi/Cargo.toml
+++ b/crates/wasi/Cargo.toml
@@ -8,7 +8,7 @@ categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 include = ["src/**/*", "README.md", "LICENSE", "build.rs"]
 build = "build.rs"
 
diff --git a/crates/wasmtime/Cargo.toml b/crates/wasmtime/Cargo.toml
index dbdc1c65b3..5331d2c07a 100644
--- a/crates/wasmtime/Cargo.toml
+++ b/crates/wasmtime/Cargo.toml
@@ -7,7 +7,7 @@ documentation = "https://docs.rs/wasmtime"
 license = "Apache-2.0 WITH LLVM-exception"
 repository = "https://github.com/bytecodealliance/wasmtime"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [package.metadata.docs.rs]
 rustdoc-args = ["--cfg", "nightlydoc"]
diff --git a/crates/wast/Cargo.toml b/crates/wast/Cargo.toml
index bb08763c08..91b4d3a88b 100644
--- a/crates/wast/Cargo.toml
+++ b/crates/wast/Cargo.toml
@@ -7,7 +7,7 @@ license = "Apache-2.0 WITH LLVM-exception"
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
 repository = "https://github.com/bytecodealliance/wasmtime"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 anyhow = "1.0.19"
diff --git a/crates/wiggle/Cargo.toml b/crates/wiggle/Cargo.toml
index 955c5ac98e..a3f2016bc3 100644
--- a/crates/wiggle/Cargo.toml
+++ b/crates/wiggle/Cargo.toml
@@ -2,7 +2,7 @@
 name = "wiggle"
 version = "0.36.0"
 authors = ["Pat Hickey <phickey@fastly.com>", "Jakub Konka <kubkonk@jakubkonka.com>", "Alex Crichton <alex@alexcrichton.com>"]
-edition = "2018"
+edition = "2021"
 license = "Apache-2.0 WITH LLVM-exception"
 description = "Runtime components of wiggle code generator"
 categories = ["wasm"]
diff --git a/crates/wiggle/generate/Cargo.toml b/crates/wiggle/generate/Cargo.toml
index 6e12f47125..26e7a35e31 100644
--- a/crates/wiggle/generate/Cargo.toml
+++ b/crates/wiggle/generate/Cargo.toml
@@ -3,7 +3,7 @@ name = "wiggle-generate"
 version = "0.36.0"
 authors = ["Pat Hickey <phickey@fastly.com>", "Jakub Konka <kubkon@jakubkonka.com>", "Alex Crichton <alex@alexcrichton.com>"]
 license = "Apache-2.0 WITH LLVM-exception"
-edition = "2018"
+edition = "2021"
 description = "Library crate for wiggle code generator."
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
diff --git a/crates/wiggle/macro/Cargo.toml b/crates/wiggle/macro/Cargo.toml
index 01ba9648dd..414f8d9633 100644
--- a/crates/wiggle/macro/Cargo.toml
+++ b/crates/wiggle/macro/Cargo.toml
@@ -2,7 +2,7 @@
 name = "wiggle-macro"
 version = "0.36.0"
 authors = ["Pat Hickey <phickey@fastly.com>", "Jakub Konka <kubkon@jakubkonka.com>", "Alex Crichton <alex@alexcrichton.com>"]
-edition = "2018"
+edition = "2021"
 license = "Apache-2.0 WITH LLVM-exception"
 description = "Wiggle code generator"
 categories = ["wasm"]
diff --git a/crates/wiggle/test-helpers/Cargo.toml b/crates/wiggle/test-helpers/Cargo.toml
index b8360ec375..f8956f1cc6 100644
--- a/crates/wiggle/test-helpers/Cargo.toml
+++ b/crates/wiggle/test-helpers/Cargo.toml
@@ -3,7 +3,7 @@ name = "wiggle-test"
 version = "0.21.0"
 authors = ["Pat Hickey <phickey@fastly.com>", "Jakub Konka <kubkon@jakubkonka.com>", "Alex Crichton <alex@alexcrichton.com>"]
 license = "Apache-2.0 WITH LLVM-exception"
-edition = "2018"
+edition = "2021"
 description = "Reusable testing components for wiggle code generator. Only intended to be used by tests in `wiggle` crate."
 categories = ["wasm"]
 keywords = ["webassembly", "wasm"]
diff --git a/docs/rust_wasi_markdown_parser/Cargo.toml b/docs/rust_wasi_markdown_parser/Cargo.toml
index d86767178d..a9562ff1a4 100644
--- a/docs/rust_wasi_markdown_parser/Cargo.toml
+++ b/docs/rust_wasi_markdown_parser/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "rust_wasi_markdown_parser"
 version = "0.1.0"
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
diff --git a/examples/fib-debug/wasm/Cargo.toml b/examples/fib-debug/wasm/Cargo.toml
index acf9c47e2f..483a0b05a7 100644
--- a/examples/fib-debug/wasm/Cargo.toml
+++ b/examples/fib-debug/wasm/Cargo.toml
@@ -2,7 +2,7 @@
 name = "example-fib-debug-wasm"
 version = "0.0.0"
 authors = ["The Wasmtime Project Developers"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [lib]
diff --git a/examples/tokio/wasm/Cargo.toml b/examples/tokio/wasm/Cargo.toml
index 5704f79630..44894a82af 100644
--- a/examples/tokio/wasm/Cargo.toml
+++ b/examples/tokio/wasm/Cargo.toml
@@ -2,7 +2,7 @@
 name = "example-tokio-wasm"
 version = "0.0.0"
 authors = ["The Wasmtime Project Developers"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [[bin]]
diff --git a/examples/wasi/wasm/Cargo.toml b/examples/wasi/wasm/Cargo.toml
index 584b13470f..b8c0225881 100644
--- a/examples/wasi/wasm/Cargo.toml
+++ b/examples/wasi/wasm/Cargo.toml
@@ -2,7 +2,7 @@
 name = "example-wasi-wasm"
 version = "0.0.0"
 authors = ["The Wasmtime Project Developers"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [[bin]]
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index e0446eb8d4..b9f51265a4 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -2,7 +2,7 @@
 name = "wasmtime-fuzz"
 version = "0.0.0"
 authors = ["The Wasmtime Project Developers"]
-edition = "2018"
+edition = "2021"
 publish = false
 
 [package.metadata]
diff --git a/tests/all/custom_signal_handler.rs b/tests/all/custom_signal_handler.rs
index bcaa3fae15..5b6c517ddf 100644
--- a/tests/all/custom_signal_handler.rs
+++ b/tests/all/custom_signal_handler.rs
@@ -111,7 +111,6 @@ mod tests {
                     move |mut caller: Caller<'_, _>| {
                         let mem = caller.get_export("memory").unwrap().into_memory().unwrap();
                         let memory = mem.data(&caller);
-                        use std::convert::TryInto;
                         i32::from_le_bytes(memory[0..4].try_into().unwrap())
                     }
                 });