compilers/mixins/emscripten: Implement thread support

Emscripten has pthread support (as well as C++ threads), but we don't
currently implement them. This fixes that by adding the necessary code.
The one thing I'm not sure about is setting the pool size. The docs
suggest that you really want to do this to ensure that your code works
correctly, but the number should really be configurable, not sure how to
set that.

Fixes #6684

1 files changed, 13 insertions, 0 deletions

diff --git a/test cases/wasm/2 threads/threads.cpp b/test cases/wasm/2 threads/threads.cpp
new file mode 100644
index 000000000..1caa73da3
--- /dev/null
+++ b/test cases/wasm/2 threads/threads.cpp
@@ -0,0 +1,13 @@
+#include <unistd.h>
+#include <iostream>
+#include <thread>
+
+int main(void) {
+    std::cout << "Before thread" << std::endl;
+    std::thread t([]() {
+        sleep(1);
+        std::cout << "In a thread." << std::endl;
+    });
+    t.join();
+    std::cout << "After thread" << std::endl;
+}