Automatically enable cross-crate inlining for small functions

Author: saethlin

alloc/src/raw_vec.rs

@@ -530,6 +530,7 @@ fn alloc_guard(alloc_size: usize) -> Result<(), TryReserveError> {
 // ensure that the code generation related to these panics is minimal as there's
 // only one location which panics rather than a bunch throughout the module.
 #[cfg(not(no_global_oom_handling))]
+#[inline(never)]
 fn capacity_overflow() -> ! {
     panic!("capacity overflow");
 }

std/src/rt.rs

@@ -155,6 +155,7 @@ fn lang_start_internal(
 }
 
 #[cfg(not(test))]
+#[inline(never)]
 #[lang = "start"]
 fn lang_start<T: crate::process::Termination + 'static>(
     main: fn() -> T,