Support compiling on wasm targets (Supersede #1068)

.github/workflows/main.yml

@@ -171,6 +171,23 @@ jobs:
       - run: cargo test -Z build-std=std ${{ matrix.no_run }} --workspace --target ${{ matrix.target }} --release
       - run: cargo test -Z build-std=std ${{ matrix.no_run }} --workspace --target ${{ matrix.target }} --features parallel
 
+  check-wasm:
+    name: Test wasm
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target: [wasm32-unknown-unknown]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Rust (rustup)
+        run: |
+          rustup target add ${{ matrix.target }}
+        shell: bash
+      - uses: Swatinem/rust-cache@v2
+      - run: cargo test --no-run --target ${{ matrix.target }}
+      - run: cargo test --no-run --target ${{ matrix.target }} --release
+      - run: cargo test --no-run --target ${{ matrix.target }} --features parallel
+
   cuda:
     name: Test CUDA support
     runs-on: ubuntu-20.04

src/command_helpers.rs

@@ -130,6 +130,8 @@ impl StderrForwarder {
                             self.bytes_available_failed = true;
                             MIN_BUFFER_CAPACITY
                         }
+                        #[cfg(target_family = "wasm")]
+                        Err(_) => panic!("bytes_available should always succeed on wasm"),
                         Ok(bytes_available) => MIN_BUFFER_CAPACITY.max(bytes_available),
                     }
                 } else {

src/parallel/stderr.rs

@@ -1,9 +1,10 @@
+#![cfg_attr(target_family = "wasm", allow(unused))]
 /// Helpers functions for [ChildStderr].
 use std::{convert::TryInto, process::ChildStderr};
 
 use crate::{Error, ErrorKind};
 
-#[cfg(all(not(unix), not(windows)))]
+#[cfg(all(not(unix), not(windows), not(target_family = "wasm")))]
 compile_error!("Only unix and windows support non-blocking pipes! For other OSes, disable the parallel feature.");
 
 #[cfg(unix)]

src/tempfile.rs

@@ -1,3 +1,5 @@
+#![cfg_attr(target_family = "wasm", allow(unused))]
+
 use std::{
     collections::hash_map::RandomState,
     fs::{remove_file, File, OpenOptions},
@@ -6,7 +8,7 @@ use std::{
     path::{Path, PathBuf},
 };
 
-#[cfg(not(any(unix, target_os = "wasi", windows)))]
+#[cfg(not(any(unix, target_family = "wasm", windows)))]
 compile_error!("Your system is not supported since cc cannot create named tempfile");
 
 fn rand() -> u64 {