Rollup merge of #74263 - RalfJung:thread-local, r=Mark-Simulacrum

Slight reorganization of sys/(fast_)thread_local

I was long confused by the `thread_local` and `fast_thread_local` modules in the `sys(_common)` part of libstd. The names make it *sound* like `fast_thread_local` is just a faster version of `thread_local`, but really these are totally different APIs: one provides thread-local "keys", which are non-addressable pointer-sized pieces of local storage with an associated destructor; the other (the "fast" one) provides just a destructor.

So I propose we rename `fast_thread_local` to `thread_local_dtor`, and `thread_local` to `thread_local_key`. That's what this PR does.

19 files changed, 27 insertions, 28 deletions

diff --git a/src/libstd/sys/cloudabi/mod.rs b/src/libstd/sys/cloudabi/mod.rs
index 8dbc31472d6..f7dd2c8d00f 100644
--- a/src/libstd/sys/cloudabi/mod.rs
+++ b/src/libstd/sys/cloudabi/mod.rs
@@ -16,8 +16,8 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-#[path = "../unix/thread_local.rs"]
-pub mod thread_local;
+#[path = "../unix/thread_local_key.rs"]
+pub mod thread_local_key;
 pub mod time;
 
 pub use crate::sys_common::os_str_bytes as os_str;
diff --git a/src/libstd/sys/hermit/mod.rs b/src/libstd/sys/hermit/mod.rs
index 7bdc1be3b17..675b82ceb77 100644
--- a/src/libstd/sys/hermit/mod.rs
+++ b/src/libstd/sys/hermit/mod.rs
@@ -22,7 +22,6 @@ pub mod cmath;
 pub mod condvar;
 pub mod env;
 pub mod ext;
-pub mod fast_thread_local;
 pub mod fd;
 pub mod fs;
 pub mod io;
@@ -37,7 +36,8 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_dtor;
+pub mod thread_local_key;
 pub mod time;
 
 use crate::io::ErrorKind;
diff --git a/src/libstd/sys/hermit/fast_thread_local.rs b/src/libstd/sys/hermit/thread_local_dtor.rs
index 9b683fce157..9b683fce157 100644
--- a/src/libstd/sys/hermit/fast_thread_local.rs
+++ b/src/libstd/sys/hermit/thread_local_dtor.rs
diff --git a/src/libstd/sys/wasm/thread_local.rs b/src/libstd/sys/hermit/thread_local_key.rs
index f8be9863ed5..bf1b49eb83b 100644
--- a/src/libstd/sys/wasm/thread_local.rs
+++ b/src/libstd/sys/hermit/thread_local_key.rs
@@ -2,25 +2,25 @@ pub type Key = usize;
 
 #[inline]
 pub unsafe fn create(_dtor: Option<unsafe extern "C" fn(*mut u8)>) -> Key {
-    panic!("should not be used on the wasm target");
+    panic!("should not be used on the hermit target");
 }
 
 #[inline]
 pub unsafe fn set(_key: Key, _value: *mut u8) {
-    panic!("should not be used on the wasm target");
+    panic!("should not be used on the hermit target");
 }
 
 #[inline]
 pub unsafe fn get(_key: Key) -> *mut u8 {
-    panic!("should not be used on the wasm target");
+    panic!("should not be used on the hermit target");
 }
 
 #[inline]
 pub unsafe fn destroy(_key: Key) {
-    panic!("should not be used on the wasm target");
+    panic!("should not be used on the hermit target");
 }
 
 #[inline]
 pub fn requires_synchronized_create() -> bool {
-    panic!("should not be used on the wasm target");
+    panic!("should not be used on the hermit target");
 }
diff --git a/src/libstd/sys/sgx/mod.rs b/src/libstd/sys/sgx/mod.rs
index 397dd496ae8..a4968ff7d4f 100644
--- a/src/libstd/sys/sgx/mod.rs
+++ b/src/libstd/sys/sgx/mod.rs
@@ -30,7 +30,7 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_key;
 pub mod time;
 
 pub use crate::sys_common::os_str_bytes as os_str;
diff --git a/src/libstd/sys/sgx/thread_local.rs b/src/libstd/sys/sgx/thread_local_key.rs
index b21784475f0..b21784475f0 100644
--- a/src/libstd/sys/sgx/thread_local.rs
+++ b/src/libstd/sys/sgx/thread_local_key.rs
diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs
index b1688e74173..eddf00d3979 100644
--- a/src/libstd/sys/unix/mod.rs
+++ b/src/libstd/sys/unix/mod.rs
@@ -47,7 +47,6 @@ pub mod cmath;
 pub mod condvar;
 pub mod env;
 pub mod ext;
-pub mod fast_thread_local;
 pub mod fd;
 pub mod fs;
 pub mod io;
@@ -68,7 +67,8 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_dtor;
+pub mod thread_local_key;
 pub mod time;
 
 pub use crate::sys_common::os_str_bytes as os_str;
diff --git a/src/libstd/sys/unix/fast_thread_local.rs b/src/libstd/sys/unix/thread_local_dtor.rs
index 8730b4de8be..c3275eb6f0e 100644
--- a/src/libstd/sys/unix/fast_thread_local.rs
+++ b/src/libstd/sys/unix/thread_local_dtor.rs
@@ -1,6 +1,9 @@
 #![cfg(target_thread_local)]
 #![unstable(feature = "thread_local_internals", issue = "none")]
 
+//! Provides thread-local destructors without an associated "key", which
+//! can be more efficient.
+
 // Since what appears to be glibc 2.18 this symbol has been shipped which
 // GCC and clang both use to invoke destructors in thread_local globals, so
 // let's do the same!
@@ -16,7 +19,7 @@
 ))]
 pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
     use crate::mem;
-    use crate::sys_common::thread_local::register_dtor_fallback;
+    use crate::sys_common::thread_local_dtor::register_dtor_fallback;
 
     extern "C" {
         #[linkage = "extern_weak"]
diff --git a/src/libstd/sys/unix/thread_local.rs b/src/libstd/sys/unix/thread_local_key.rs
index 2c5b94b1e61..2c5b94b1e61 100644
--- a/src/libstd/sys/unix/thread_local.rs
+++ b/src/libstd/sys/unix/thread_local_key.rs
diff --git a/src/libstd/sys/vxworks/mod.rs b/src/libstd/sys/vxworks/mod.rs
index 0787e709898..1132a849e2f 100644
--- a/src/libstd/sys/vxworks/mod.rs
+++ b/src/libstd/sys/vxworks/mod.rs
@@ -13,7 +13,6 @@ pub mod cmath;
 pub mod condvar;
 pub mod env;
 pub mod ext;
-pub mod fast_thread_local;
 pub mod fd;
 pub mod fs;
 pub mod io;
@@ -29,7 +28,8 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_dtor;
+pub mod thread_local_key;
 pub mod time;
 
 pub use crate::sys_common::os_str_bytes as os_str;
diff --git a/src/libstd/sys/vxworks/fast_thread_local.rs b/src/libstd/sys/vxworks/thread_local_dtor.rs
index 098668cf521..3f73f6c4903 100644
--- a/src/libstd/sys/vxworks/fast_thread_local.rs
+++ b/src/libstd/sys/vxworks/thread_local_dtor.rs
@@ -5,7 +5,3 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern "C" fn(*mut u8)) {
     use crate::sys_common::thread_local::register_dtor_fallback;
     register_dtor_fallback(t, dtor);
 }
-
-pub fn requires_move_before_drop() -> bool {
-    false
-}
diff --git a/src/libstd/sys/vxworks/thread_local.rs b/src/libstd/sys/vxworks/thread_local_key.rs
index 2c5b94b1e61..2c5b94b1e61 100644
--- a/src/libstd/sys/vxworks/thread_local.rs
+++ b/src/libstd/sys/vxworks/thread_local_key.rs
diff --git a/src/libstd/sys/wasi/mod.rs b/src/libstd/sys/wasi/mod.rs
index 4fe9661421b..85f5282034f 100644
--- a/src/libstd/sys/wasi/mod.rs
+++ b/src/libstd/sys/wasi/mod.rs
@@ -36,8 +36,6 @@ pub mod net;
 pub mod os;
 pub use crate::sys_common::os_str_bytes as os_str;
 pub mod ext;
-#[path = "../wasm/fast_thread_local.rs"]
-pub mod fast_thread_local;
 pub mod path;
 pub mod pipe;
 pub mod process;
@@ -47,8 +45,10 @@ pub mod rwlock;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-#[path = "../wasm/thread_local.rs"]
-pub mod thread_local;
+#[path = "../wasm/thread_local_dtor.rs"]
+pub mod thread_local_dtor;
+#[path = "../wasm/thread_local_key.rs"]
+pub mod thread_local_key;
 pub mod time;
 
 #[cfg(not(test))]
diff --git a/src/libstd/sys/wasm/mod.rs b/src/libstd/sys/wasm/mod.rs
index 050e8099af4..6939596e52d 100644
--- a/src/libstd/sys/wasm/mod.rs
+++ b/src/libstd/sys/wasm/mod.rs
@@ -20,7 +20,6 @@ pub mod alloc;
 pub mod args;
 pub mod cmath;
 pub mod env;
-pub mod fast_thread_local;
 pub mod fs;
 pub mod io;
 pub mod memchr;
@@ -32,7 +31,8 @@ pub mod process;
 pub mod stack_overflow;
 pub mod stdio;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_dtor;
+pub mod thread_local_key;
 pub mod time;
 
 pub use crate::sys_common::os_str_bytes as os_str;
diff --git a/src/libstd/sys/wasm/fast_thread_local.rs b/src/libstd/sys/wasm/thread_local_dtor.rs
index 85d66098302..85d66098302 100644
--- a/src/libstd/sys/wasm/fast_thread_local.rs
+++ b/src/libstd/sys/wasm/thread_local_dtor.rs
diff --git a/src/libstd/sys/hermit/thread_local.rs b/src/libstd/sys/wasm/thread_local_key.rs
index f8be9863ed5..f8be9863ed5 100644
--- a/src/libstd/sys/hermit/thread_local.rs
+++ b/src/libstd/sys/wasm/thread_local_key.rs
diff --git a/src/libstd/sys/windows/mod.rs b/src/libstd/sys/windows/mod.rs
index 193ab5b47ef..9a52371280e 100644
--- a/src/libstd/sys/windows/mod.rs
+++ b/src/libstd/sys/windows/mod.rs
@@ -20,7 +20,6 @@ pub mod cmath;
 pub mod condvar;
 pub mod env;
 pub mod ext;
-pub mod fast_thread_local;
 pub mod fs;
 pub mod handle;
 pub mod io;
@@ -35,7 +34,8 @@ pub mod process;
 pub mod rand;
 pub mod rwlock;
 pub mod thread;
-pub mod thread_local;
+pub mod thread_local_dtor;
+pub mod thread_local_key;
 pub mod time;
 cfg_if::cfg_if! {
     if #[cfg(not(target_vendor = "uwp"))] {
diff --git a/src/libstd/sys/windows/fast_thread_local.rs b/src/libstd/sys/windows/thread_local_dtor.rs
index 191fa07f32a..7be13bc4b2b 100644
--- a/src/libstd/sys/windows/fast_thread_local.rs
+++ b/src/libstd/sys/windows/thread_local_dtor.rs
@@ -1,4 +1,4 @@
 #![unstable(feature = "thread_local_internals", issue = "none")]
 #![cfg(target_thread_local)]
 
-pub use crate::sys_common::thread_local::register_dtor_fallback as register_dtor;
+pub use crate::sys_common::thread_local_dtor::register_dtor_fallback as register_dtor;
diff --git a/src/libstd/sys/windows/thread_local.rs b/src/libstd/sys/windows/thread_local_key.rs
index e0bb102b3af..e0bb102b3af 100644
--- a/src/libstd/sys/windows/thread_local.rs
+++ b/src/libstd/sys/windows/thread_local_key.rs