Some arg Fun in Rust. (0.38.1)

src/bytecode.c

@@ -207,6 +207,7 @@ static const char *opcode_name(OpCode op) {
         case OP_FMIN: return "FMIN";
         case OP_FMAX: return "FMAX";
         case OP_RUST_HELLO: return "RUST_HELLO";
+        case OP_RUST_HELLO_ARGS: return "RUST_HELLO_ARGS";
         default: return "???";
     }
 }

src/bytecode.h

@@ -265,6 +265,7 @@ typedef enum {
 
     // Rust FFI demo opcode(s)
     OP_RUST_HELLO,        // pushes string returned from Rust (hello world)
+    OP_RUST_HELLO_ARGS,   // pops message string; prints it via Rust; pushes Nil
 
     /* Notcurses TUI (optional) */
     OP_NC_INIT,           // initializes Notcurses; returns 1 on success, 0 on failure

src/parser.c

@@ -793,6 +793,14 @@ static int emit_primary(Bytecode *bc, const char *src, size_t len, size_t *pos)
                 free(name);
                 return 1;
             }
+            if (strcmp(name, "rust_hello_args") == 0) {
+                (*pos)++; /* '(' */
+                if (!emit_expression(bc, src, len, pos)) { parser_fail(*pos, "rust_hello_args expects (message:string)"); free(name); return 0; }
+                if (!consume_char(src, len, pos, ')')) { parser_fail(*pos, "Expected ')' after rust_hello_args arg"); free(name); return 0; }
+                bytecode_add_instruction(bc, OP_RUST_HELLO_ARGS, 0);
+                free(name);
+                return 1;
+            }
             if (strcmp(name, "os_list_dir") == 0) {
                 (*pos)++; /* '(' */
                 if (!emit_expression(bc, src, len, pos)) { parser_fail(*pos, "os_list_dir expects (path)"); free(name); return 0; }

src/rust/Cargo.toml

@@ -6,6 +6,9 @@ edition = "2021"
 [lib]
 crate-type = ["staticlib"]
 
+[profile.dev]
+panic = "abort"
+
 [profile.release]
 panic = "abort"
 # Optimize for minimal size

src/rust/eh_personality.c

@@ -0,0 +1,2 @@
+/* Workaround for linking Rust staticlib in no_std/abort mode on some toolchains */
+void rust_eh_personality(void) {}

src/rust/src/lib.rs

@@ -11,8 +11,8 @@
 
 #![no_std]
 
-#[repr(C)]
-pub struct Vm;
+// Use an FFI-safe opaque handle for the VM pointer
+pub type Vm = core::ffi::c_void;
 
 extern "C" {
     fn vm_pop_i64(vm: *mut Vm) -> i64;
@@ -37,6 +37,23 @@ pub extern "C" fn fun_rust_get_string() -> *const core::ffi::c_char {
     b"Hello from Rust ops!\0".as_ptr() as *const _
 }
 
+// Print a C string via libc printf to stdout (acceptable under no_std via extern)
+#[no_mangle]
+pub extern "C" fn fun_rust_print_string(msg: *const core::ffi::c_char) -> i32 {
+    unsafe {
+        extern "C" {
+            fn printf(fmt: *const core::ffi::c_char, ...) -> i32;
+        }
+        let fmt = b"%s\n\0".as_ptr() as *const core::ffi::c_char;
+        printf(fmt, msg);
+    }
+    0
+}
+
+// Provide personality symbol to satisfy some linkers in no_std builds
+#[no_mangle]
+pub extern "C" fn rust_eh_personality() {}
+
 // Minimal panic handler for no_std; abort behavior requested via Cargo profile
 #[panic_handler]
 fn panic(_info: &core::panic::PanicInfo) -> ! {

src/vm.h

@@ -56,7 +56,7 @@ static const char *opcode_names[] = {
     "TRY_PUSH","TRY_POP","THROW",
     "FMIN","FMAX",
     /* Rust FFI demo */
-    "RUST_HELLO",
+    "RUST_HELLO","RUST_HELLO_ARGS",
     /* Notcurses TUI (optional) */
     "NC_INIT","NC_SHUTDOWN","NC_CLEAR","NC_DRAW_TEXT","NC_GETCH"
 };
@@ -157,5 +157,7 @@ int fun_op_radd(VM *vm);
 
 /* Example Rust function returning a demo C string (null-terminated). */
 const char *fun_rust_get_string(void);
+/* Rust function that prints a passed C string, returns 0 on success. */
+int fun_rust_print_string(const char *msg);
 
 #endif

src/vm/rust/hello.c

@@ -25,3 +25,29 @@ case OP_RUST_HELLO: {
 #endif
     break;
 }
+
+/*
+ * Rust FFI demo opcode with argument: OP_RUST_HELLO_ARGS
+ * Pops a string from the stack and asks Rust to print it. Pushes Nil.
+ */
+case OP_RUST_HELLO_ARGS: {
+#ifdef FUN_WITH_RUST
+    Value vmsg = pop_value(vm);
+    char *msg = value_to_string_alloc(&vmsg);
+    free_value(vmsg);
+    if (msg) {
+        fun_rust_print_string(msg);
+        free(msg);
+    } else {
+        fun_rust_print_string("");
+    }
+    push_value(vm, make_nil());
+#else
+    /* Still pop and free the arg to keep stack sane */
+    Value vmsg = pop_value(vm);
+    free_value(vmsg);
+    vm_raise_error(vm, "RUST_HELLO_ARGS requires FUN_WITH_RUST=ON at build time");
+    push_value(vm, make_nil());
+#endif
+    break;
+}