use linkage = 'weak' for missing intrinsic stub (esp-rs#191)

Author: MabezDev

esp-wifi/src/common_adapter/mod.rs

@@ -469,6 +469,7 @@ pub unsafe extern "C" fn strrchr(_s: *const (), _c: u32) -> *const u8 {
 }
 
 #[no_mangle]
+#[linkage = "weak"]
 pub unsafe extern "C" fn floor(_v: f64) -> f64 {
     todo!("floor")
 }

esp-wifi/src/lib.rs

@@ -1,6 +1,7 @@
 #![no_std]
 #![cfg_attr(target_arch = "xtensa", feature(asm_experimental_arch))]
 #![feature(c_variadic)]
+#![feature(linkage)]
 #![cfg_attr(feature = "async", feature(async_fn_in_trait))]
 #![cfg_attr(feature = "async", allow(incomplete_features))]