Auto merge of #56813 - oli-obk:main_🧶, r=pnkfelix

Always run rustc in a thread

cc @ishitatsuyuki @eddyb

r? @pnkfelix

[Previously](https://github.com/rust-lang/rust/pull/48575) we moved to only producing threads when absolutely necessary. Even before we opted to only create threads in some cases, which [is unsound](https://github.com/rust-lang/rust/pull/48575#issuecomment-380635967) due to the way we use thread local storage.

7 files changed, 0 insertions, 41 deletions

diff --git a/src/libstd/rt.rs b/src/libstd/rt.rs
index 9e957bd87d7..fdaf2a821fa 100644
--- a/src/libstd/rt.rs
+++ b/src/libstd/rt.rs
@@ -73,18 +73,3 @@ fn lang_start<T: ::process::Termination + 'static>
 {
     lang_start_internal(&move || main().report(), argc, argv)
 }
-
-/// Function used for reverting changes to the main stack before setrlimit().
-/// This is POSIX (non-Linux) specific and unlikely to be directly stabilized.
-#[unstable(feature = "rustc_stack_internals", issue = "0")]
-pub unsafe fn deinit_stack_guard() {
-    ::sys::thread::guard::deinit();
-}
-
-/// Function used for resetting the main stack guard address after setrlimit().
-/// This is POSIX specific and unlikely to be directly stabilized.
-#[unstable(feature = "rustc_stack_internals", issue = "0")]
-pub unsafe fn update_stack_guard() {
-    let main_guard = ::sys::thread::guard::init();
-    ::sys_common::thread_info::reset_guard(main_guard);
-}
diff --git a/src/libstd/sys/cloudabi/thread.rs b/src/libstd/sys/cloudabi/thread.rs
index 177321439d8..a64e0f06849 100644
--- a/src/libstd/sys/cloudabi/thread.rs
+++ b/src/libstd/sys/cloudabi/thread.rs
@@ -121,7 +121,6 @@ pub mod guard {
     pub unsafe fn init() -> Option<Guard> {
         None
     }
-    pub unsafe fn deinit() {}
 }
 
 fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
diff --git a/src/libstd/sys/redox/thread.rs b/src/libstd/sys/redox/thread.rs
index ff861805382..ca014fd576b 100644
--- a/src/libstd/sys/redox/thread.rs
+++ b/src/libstd/sys/redox/thread.rs
@@ -92,5 +92,4 @@ pub mod guard {
     pub type Guard = !;
     pub unsafe fn current() -> Option<Guard> { None }
     pub unsafe fn init() -> Option<Guard> { None }
-    pub unsafe fn deinit() {}
 }
diff --git a/src/libstd/sys/sgx/thread.rs b/src/libstd/sys/sgx/thread.rs
index 9de12a5e6f1..9f3c4536cb5 100644
--- a/src/libstd/sys/sgx/thread.rs
+++ b/src/libstd/sys/sgx/thread.rs
@@ -97,5 +97,4 @@ pub mod guard {
     pub type Guard = !;
     pub unsafe fn current() -> Option<Guard> { None }
     pub unsafe fn init() -> Option<Guard> { None }
-    pub unsafe fn deinit() {}
 }
diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index 4ff060018ae..e0d2c620498 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -211,7 +211,6 @@ pub mod guard {
     pub type Guard = Range<usize>;
     pub unsafe fn current() -> Option<Guard> { None }
     pub unsafe fn init() -> Option<Guard> { None }
-    pub unsafe fn deinit() {}
 }
 
 
@@ -355,26 +354,6 @@ pub mod guard {
         }
     }
 
-    pub unsafe fn deinit() {
-        if !cfg!(target_os = "linux") {
-            if let Some(stackaddr) = get_stack_start_aligned() {
-                // Remove the protection on the guard page.
-                // FIXME: we cannot unmap the page, because when we mmap()
-                // above it may be already mapped by the OS, which we can't
-                // detect from mmap()'s return value. If we unmap this page,
-                // it will lead to failure growing stack size on platforms like
-                // macOS. Instead, just restore the page to a writable state.
-                // This ain't Linux, so we probably don't need to care about
-                // execstack.
-                let result = mprotect(stackaddr, PAGE_SIZE, PROT_READ | PROT_WRITE);
-
-                if result != 0 {
-                    panic!("unable to reset the guard page");
-                }
-            }
-        }
-    }
-
     #[cfg(any(target_os = "macos",
               target_os = "bitrig",
               target_os = "openbsd",
diff --git a/src/libstd/sys/wasm/thread.rs b/src/libstd/sys/wasm/thread.rs
index 3d74ffdc14a..f9abb0b825a 100644
--- a/src/libstd/sys/wasm/thread.rs
+++ b/src/libstd/sys/wasm/thread.rs
@@ -68,7 +68,6 @@ pub mod guard {
     pub type Guard = !;
     pub unsafe fn current() -> Option<Guard> { None }
     pub unsafe fn init() -> Option<Guard> { None }
-    pub unsafe fn deinit() {}
 }
 
 cfg_if! {
diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index 1a97dd10ced..621ae2fda58 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -98,5 +98,4 @@ pub mod guard {
     pub type Guard = !;
     pub unsafe fn current() -> Option<Guard> { None }
     pub unsafe fn init() -> Option<Guard> { None }
-    pub unsafe fn deinit() {}
 }