Build a Wasm test platform in test_gen

compiler/test_gen/build.rs

@@ -0,0 +1,53 @@
+use std::env;
+use std::ffi::OsStr;
+use std::path::Path;
+use std::process::Command;
+
+pub const PLATFORM_FILENAME: &str = "wasm_test_platform";
+pub const DIRNAME_VAR: &str = "TEST_GEN_OUT";
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+    println!("cargo:rerun-if-changed=src/helpers/{}.c", PLATFORM_FILENAME);
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+
+    println!("cargo:rustc-env={}={}", DIRNAME_VAR, out_dir);
+
+    run_command(
+        Path::new("."),
+        "zig",
+        [
+            "build-obj",
+            "-target",
+            "wasm32-wasi",
+            "-lc",
+            &format!("src/helpers/{}.c", PLATFORM_FILENAME),
+            &format!("-femit-bin={}/{}.o", out_dir, PLATFORM_FILENAME),
+        ],
+    );
+}
+
+fn run_command<S, I, P: AsRef<Path>>(path: P, command_str: &str, args: I)
+where
+    I: IntoIterator<Item = S>,
+    S: AsRef<OsStr>,
+{
+    let output_result = Command::new(OsStr::new(&command_str))
+        .current_dir(path)
+        .args(args)
+        .output();
+    match output_result {
+        Ok(output) => match output.status.success() {
+            true => (),
+            false => {
+                let error_str = match std::str::from_utf8(&output.stderr) {
+                    Ok(stderr) => stderr.to_string(),
+                    Err(_) => format!("Failed to run \"{}\"", command_str),
+                };
+                panic!("{} failed: {}", command_str, error_str);
+            }
+        },
+        Err(reason) => panic!("{} failed: {}", command_str, reason),
+    }
+}

compiler/test_gen/src/helpers/wasm_test_platform.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+
+void *roc_alloc(size_t size, unsigned int alignment) { return malloc(size); }
+
+void *roc_realloc(void *ptr, size_t new_size, size_t old_size,
+                  unsigned int alignment)
+{
+    return realloc(ptr, new_size);
+}
+
+void roc_dealloc(void *ptr, unsigned int alignment) { free(ptr); }
+
+void roc_panic(void *ptr, unsigned int alignment)
+{
+    char *msg = (char *)ptr;
+    fprintf(stderr,
+            "Application crashed with message\n\n    %s\n\nShutting down\n", msg);
+    exit(0);
+}
+
+void *roc_memcpy(void *dest, const void *src, size_t n)
+{
+    return memcpy(dest, src, n);
+}
+
+void *roc_memset(void *str, int c, size_t n) { return memset(str, c, n); }