Document that `init` and `cleanup` are not guaranteed to run

5 files changed, 10 insertions, 0 deletions

diff --git a/library/std/src/sys/hermit/mod.rs b/library/std/src/sys/hermit/mod.rs
index 77c068e1a97..a70d1db7ca6 100644
--- a/library/std/src/sys/hermit/mod.rs
+++ b/library/std/src/sys/hermit/mod.rs
@@ -96,12 +96,14 @@ pub extern "C" fn __rust_abort() {
 }
 
 // SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(argc: isize, argv: *const *const u8) {
     let _ = net::init();
     args::init(argc, argv);
 }
 
 // SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {
     args::cleanup();
 }
diff --git a/library/std/src/sys/sgx/mod.rs b/library/std/src/sys/sgx/mod.rs
index 25250d060d0..059d6cb5ba1 100644
--- a/library/std/src/sys/sgx/mod.rs
+++ b/library/std/src/sys/sgx/mod.rs
@@ -40,6 +40,7 @@ pub mod time;
 pub use crate::sys_common::os_str_bytes as os_str;
 
 // SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(argc: isize, argv: *const *const u8) {
     unsafe {
         args::init(argc, argv);
@@ -47,6 +48,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
 }
 
 // SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {}
 
 /// This function is used to implement functionality that simply doesn't exist.
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index 8ae0c1120ff..a0ee69c2f72 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -45,6 +45,7 @@ pub mod time;
 pub use crate::sys_common::os_str_bytes as os_str;
 
 // SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(argc: isize, argv: *const *const u8) {
     // The standard streams might be closed on application startup. To prevent
     // std::io::{stdin, stdout,stderr} objects from using other unrelated file
@@ -120,6 +121,7 @@ pub unsafe fn init(argc: isize, argv: *const *const u8) {
 }
 
 // SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {
     args::cleanup();
     stack_overflow::cleanup();
diff --git a/library/std/src/sys/unsupported/common.rs b/library/std/src/sys/unsupported/common.rs
index c60c2a9b8e8..6e72a7c632e 100644
--- a/library/std/src/sys/unsupported/common.rs
+++ b/library/std/src/sys/unsupported/common.rs
@@ -11,9 +11,11 @@ pub use crate::sys_common::os_str_bytes as os_str;
 use crate::os::raw::c_char;
 
 // SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}
 
 // SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {}
 
 pub fn unsupported<T>() -> std_io::Result<T> {
diff --git a/library/std/src/sys/windows/mod.rs b/library/std/src/sys/windows/mod.rs
index 21fec2aa01b..ddb6ac5f55c 100644
--- a/library/std/src/sys/windows/mod.rs
+++ b/library/std/src/sys/windows/mod.rs
@@ -50,11 +50,13 @@ cfg_if::cfg_if! {
 }
 
 // SAFETY: must be called only once during runtime initialization.
+// NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
     stack_overflow::init();
 }
 
 // SAFETY: must be called only once during runtime cleanup.
+// NOTE: this is not guaranteed to run, for example when the program aborts.
 pub unsafe fn cleanup() {
     net::cleanup();
 }