Trying to understand why format blows up

src/crt.rs

@@ -1,5 +1,6 @@
 #[no_mangle]
 pub extern "C" fn strcmp(first: *const u8, second: *const u8) -> bool {
+    print("crt::strcmp");
     todo!()
 }
 
@@ -50,40 +51,60 @@ pub extern "C" fn truncf(f: f32) -> f32 {
 
 #[no_mangle]
 pub extern "C" fn trunc(f: f64) -> f64 {
+    print("crt::trunc");
     todo!()
 }
 
 #[no_mangle]
 pub extern "C" fn sqrtf(f: f32) -> f32 {
+    print("crt::sqrtf");
     todo!()
 }
 
 #[no_mangle]
 pub extern "C" fn sqrt(f: f64) -> f64 {
+    print("crt::sqrt");
     todo!()
 }
 
 #[no_mangle]
 pub extern "C" fn rintf(f: f32) -> f32 {
+    print("crt::rintf");
     todo!()
 }
 
 #[no_mangle]
 pub extern "C" fn rint(f: f64) -> f64 {
+    print("crt::rint");
     todo!()
 }
 
 #[no_mangle]
 pub extern "C" fn __popcountdi2(num: u32) -> u32 {
+    print("crt::popcount");
     todo!()
 }
 
 #[no_mangle]
 pub extern "C" fn abort() {
+    print("crt::abort");
     todo!()
 }
 
 #[no_mangle]
-pub extern "C" fn vsnprintf(buffer: *mut u8, count: usize, format: *const u8, args: *const u8 /* TODO: va_list */) -> f64 {
+pub extern "C" fn vsnprintf(buffer: *mut u8, count: usize, format: *const u8, args: *const u8 /* TODO: va_list */) -> u32 {
+    print("crt::vsnprinf");
     todo!()
 }
+
+fn print(s: &str) {
+    for c in s.as_bytes() {
+        outb(42, *c);
+    }
+}
+
+fn outb(_port: u8, value: u8) {
+    unsafe {
+        asm!("out 42, al", /* in(reg_byte) port, */ in("al") value);
+    }
+}

src/main.rs

@@ -5,9 +5,13 @@
 #![feature(alloc_error_handler)]
 #![feature(asm)]
 
+#![feature(fmt_internals)]
+
 extern crate alloc;
 
-use core::panic::PanicInfo;
+use core::{ops::Add, panic::PanicInfo};
+
+use alloc::{borrow::ToOwned, format};
 
 // use wasm3::Environment;
 // use wasm3::Module;
@@ -37,6 +41,32 @@ pub extern "C" fn _start() -> ! {
     allocator::init();
     print("Inited allocator\r\n");
 
+    let mut s = "foo\r\n".to_owned();
+    s.make_ascii_uppercase();
+    let s1 = s.add("bar\r\n");
+    print(&s1);
+
+    let t = "arse\r\n";
+    // let t1 = format!("{}:{}", s1, t);
+
+    print("ARGING ALL THE THINGS\r\n");
+
+    let s1_ = ::core::fmt::ArgumentV1::new(&s1, ::core::fmt::Display::fmt);
+    print("made first args arg\r\n");
+    let t_ = ::core::fmt::ArgumentV1::new(&t, ::core::fmt::Display::fmt);
+    print("made args args\r\n");
+
+    let slicey = [s1_, t_];
+
+    let fmtargs = ::core::fmt::Arguments::new_v1(&["", ":"], &slicey);
+    print("made args struct\r\n");
+
+    print("CALLING FORMAT\r\n");
+    let t1 = ::alloc::fmt::format(fmtargs);
+
+    print("PRINTING THE THING\r\n");
+    print(&t1);
+
     // let env = Environment::new()
     //     .expect("Unable to create environment");
     // let rt = env