Fix linkage issues

crates/wasmtime/src/engine.rs

@@ -101,6 +101,8 @@ impl Engine {
             // handlers, etc.
             #[cfg(all(feature = "signals-based-traps", not(miri)))]
             crate::runtime::vm::init_traps(config.macos_use_mach_ports);
+            #[cfg(feature = "debug-builtins")]
+            crate::runtime::vm::debug_builtins::init();
         }
 
         #[cfg(any(feature = "cranelift", feature = "winch"))]

crates/wasmtime/src/runtime/vm/debug_builtins.rs

@@ -33,3 +33,18 @@ pub unsafe extern "C" fn set_vmctx_memory(vmctx_ptr: *mut VMContext) {
     // TODO multi-memory
     VMCTX_AND_MEMORY = (vmctx_ptr, 0);
 }
+
+/// A bit of a hack around various linkage things. The goal here is to force the
+/// `wasmtime_*` symbols defined in `helpers.c` to actually get exported. That
+/// means they need to be referenced for the linker to include them which is
+/// what this function does with trickery in C.
+pub fn init() {
+    extern "C" {
+        #[wasmtime_versioned_export_macros::versioned_link]
+        fn wasmtime_debug_builtins_init();
+    }
+
+    unsafe {
+        wasmtime_debug_builtins_init();
+    }
+}

crates/wasmtime/src/runtime/vm/helpers.c

@@ -96,6 +96,17 @@ void VERSIONED_SYMBOL(set_vmctx_memory)(void *);
 DEBUG_BUILTIN_EXPORT void VERSIONED_SYMBOL(wasmtime_set_vmctx_memory)(void *p) {
   VERSIONED_SYMBOL(set_vmctx_memory)(p);
 }
+
+// Helper symbol called from Rust to force the above two functions to not get
+// stripped by the linker.
+void VERSIONED_SYMBOL(wasmtime_debug_builtins_init)() {
+#ifndef CFG_TARGET_OS_windows
+  void *volatile p;
+  p = (void *)&VERSIONED_SYMBOL(wasmtime_resolve_vmctx_memory_ptr);
+  p = (void *)&VERSIONED_SYMBOL(wasmtime_set_vmctx_memory);
+  (void)p;
+#endif
+}
 #endif // FEATURE_DEBUG_BUILTINS
 
 // For more information about this see `unix/unwind.rs` and the