libc linking error

[clear plank]

Hello, I'm an intermediate rust programmer. I've made no_std projects before, but now for whatever reason, the compiler won't link with libc properly. After searching, I initially thought this was because printf and various stdio functions were inlined by default and couldn't be detected, however this error also applies to any function in libc.
The code I am using is just a basic no_std program.

#![no_std]
#![no_main]

use core::panic::PanicInfo;

#[no_mangle]
pub fn mainCRTStartup() {
    main()
}

#[no_mangle]
fn main() {
    unsafe {
        libc::printf("Hello!\n\0".as_ptr() as _);
        let x = libc::malloc(32);
    }
}

#[panic_handler]
fn panic_handler(info: &PanicInfo) -> ! {
    loop{}
}

(Yes I know I should be changing the settings in the linker so I don't have to define mainCRTstartup, but this is just for demonstration purposes)
This is my cargo.toml

[package]
name = "no_std_test"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
libc = { version = "0.2.137", default-features = false }

[profile.dev]
panic = "abort"

[profile.release]
panic = "abort"

Attempting to compile gives these errors:
I've been trying to fix this for the past week so any help is appreciated!

[lament ibex]

Hmm, it doesn't find malloc.
Does it work without the malloc?

[clear plank]

Well I added the Malloc there for demonstration purposes, but I can’t use any item in libc. The 1 error is for malloc and the other 19 is for printf.
I’m able to just use winapi and disregard libc all together so I don’t know where the problem comes from

[near yarrow]

libc is a unix like system lib and not a Windows one, the equivalent on windows would be MSVCRT and it has malloc in it : https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/malloc?view=msvc-170. If you want to use an implantation in rust I would recommend the Windows-rs crate : https://github.com/microsoft/windows-rs and as for malloc part you can use : https://docs.rs/windows-sys/latest/windows_sys/Win32/System/Memory/fn.HeapAlloc.html.

[clear plank]

Ahhh I see. So then why does libc have support for windows targets? Is it just for c code interoperability?

Additionally, why does libc work when not using #![no_std]?

[near yarrow]

try to compile and link your code using libc crate against MSVCRTX.dll (replace X by 110 or 120) ; something like cargo rustc -- -C link-args="-Wl,-rpath, c:\Windows\System32\msvcr110.dll"

[near yarrow]

yes your code compiles under linux

[rapid pebble]

You need to link the C runtime and import libraries if you want to use C in Rust. See https://learn.microsoft.com/en-us/cpp/c-runtime-library/crt-library-features?view=msvc-170

Rust's std does this for you but no_std doesn't.