Disable OsStrExt ettc. on WASIp2 on stable Rust. (#1301)

`OsStrExt` and friends aren't stable on the wasm32-wasip2 target yet, so
disable features that depend on them when they aren't available.

Fixes #1060.

Author: sunfishcode

.github/workflows/main.yml

@@ -83,6 +83,7 @@ jobs:
       run: >
         rustup target add
         wasm32-wasip1
+        wasm32-wasip2
         x86_64-unknown-fuchsia
     - if: matrix.rust == '1.63'
       run: rustup target add x86_64-fuchsia
@@ -102,6 +103,8 @@ jobs:
     - run: cargo check --workspace --release -vv --target=x86_64-unknown-netbsd --features=all-apis --all-targets
     - if: matrix.rust != '1.63'
       run: cargo check --workspace --release -vv --target=wasm32-wasip1 --features=all-apis
+    - if: matrix.rust != '1.63'
+      run: cargo check --workspace --release -vv --target=wasm32-wasip2 --features=all-apis
     - if: matrix.rust != '1.63'
       run: cargo check --workspace --release -vv --target=x86_64-unknown-fuchsia --features=all-apis --all-targets
     - if: matrix.rust == '1.63'
@@ -179,10 +182,8 @@ jobs:
     - run: >
         rustup target add
         x86_64-unknown-redox
-        wasm32-wasip1
         thumbv7neon-unknown-linux-gnueabihf
     - run: cargo check --workspace --release -vv --target=x86_64-unknown-redox --features=all-apis
-    - run: cargo check --workspace --release -vv --target=wasm32-wasip1 --features=all-apis
     - run: cargo check --workspace --release -vv --target=thumbv7neon-unknown-linux-gnueabihf --features=all-apis
 
   check_tier3:

Cargo.toml

@@ -261,5 +261,6 @@ check-cfg = [
     'cfg(thumb_mode)',
     'cfg(wasi)',
     'cfg(wasi_ext)',
+    'cfg(wasip2)',
     'cfg(target_arch, values("xtensa"))',
 ]

build.rs

@@ -82,6 +82,7 @@ fn main() {
     // WASI support can utilize wasi_ext if present.
     if os == "wasi" {
         use_feature_or_nothing("wasi_ext");
+        use_feature_or_nothing("wasip2");
     }
 
     // If the libc backend is requested, or if we're not on a platform for

src/lib.rs

@@ -4,7 +4,8 @@
     all(
         target_os = "wasi",
         target_env = "p2",
-        any(feature = "fs", feature = "mount", feature = "net")
+        any(feature = "fs", feature = "mount", feature = "net"),
+        wasip2,
     ),
     feature(wasip2)
 )]