Add edition 2018 compatibility check

Author: daxpedda

.github/workflows/main.yml

@@ -558,6 +558,26 @@ jobs:
     - run: rustup update --no-self-update 1.57 && rustup default 1.57 && rustup target add ${{ matrix.target }}
     - run: cargo build --target ${{ matrix.target }} ${{ matrix.features }}
 
+  2018:
+    name: Check edition 2018 compatibility
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        target:
+          - x86_64-unknown-linux-gnu
+          - wasm32-unknown-unknown
+        features:
+          - --no-default-features
+          - ""
+    defaults:
+      run:
+        working-directory: crates/msrv/2018
+    steps:
+    - uses: actions/checkout@v4
+    - run: rustup update --no-self-update 1.57 && rustup default 1.57 && rustup target add ${{ matrix.target }}
+    - run: cargo build --target ${{ matrix.target }} ${{ matrix.features }}
+
   msrv-cli:
     name: Check MSRV for CLI tools
     runs-on: ubuntu-latest

crates/msrv/2018/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+edition = "2018"
+name = "edition-2018-test"
+publish = false
+version = "0.0.0"
+
+[features]
+default = ["std"]
+std = [
+  "wasm-bindgen/std",
+  "js-sys/std",
+  "wasm-bindgen-futures/std",
+  "web-sys/std",
+  "wasm-bindgen-test/std",
+]
+
+[dependencies]
+js-sys = { path = "../../js-sys", default-features = false }
+wasm-bindgen = { path = "../../../", default-features = false }
+wasm-bindgen-futures = { path = "../../futures", default-features = false }
+wasm-bindgen-test = { path = "../../test", default-features = false }
+web-sys = { path = "../../web-sys", default-features = false }
+
+# Pinned sub-dependencies for MSRV
+bumpalo = "=3.12.0"
+log = "=0.4.18"
+scoped-tls = { version = "=1.0.0", optional = false }