Rollup merge of rust-lang#121598 - RalfJung:catch_unwind, r=oli-obk

rename 'try' intrinsic to 'catch_unwind'

The intrinsic has nothing to do with `try` blocks, and corresponds to the stable `catch_unwind` function, so this makes a lot more sense IMO.

Also rename Miri's special function while we are at it, to reflect the level of abstraction it works on: it's an unwinding mechanism, on which Rust implements panics.

Author: matthiaskrgr

core/src/intrinsics.rs

@@ -75,6 +75,9 @@ pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
     unsafe { crate::ptr::drop_in_place(to_drop) }
 }
 
+#[cfg(bootstrap)]
+pub use self::r#try as catch_unwind;
+
 extern "rust-intrinsic" {
     // N.B., these intrinsics take raw pointers because they mutate aliased
     // memory, which is not valid for either `&` or `&mut`.
@@ -2382,16 +2385,24 @@ extern "rust-intrinsic" {
     #[rustc_nounwind]
     pub fn variant_count<T>() -> usize;
 
-    /// Rust's "try catch" construct which invokes the function pointer `try_fn`
-    /// with the data pointer `data`.
-    ///
-    /// The third argument is a function called if a panic occurs. This function
-    /// takes the data pointer and a pointer to the target-specific exception
-    /// object that was caught. For more information see the compiler's
-    /// source as well as std's catch implementation.
+    /// Rust's "try catch" construct for unwinding. Invokes the function pointer `try_fn` with the
+    /// data pointer `data`, and calls `catch_fn` if unwinding occurs while `try_fn` runs.
     ///
     /// `catch_fn` must not unwind.
+    ///
+    /// The third argument is a function called if an unwind occurs (both Rust unwinds and foreign
+    /// unwinds). This function takes the data pointer and a pointer to the target-specific
+    /// exception object that was caught. For more information, see the compiler's source as well as
+    /// std's `catch_unwind` implementation.
+    ///
+    /// The stable version of this intrinsic is `std::panic::catch_unwind`.
+    #[rustc_nounwind]
+    #[cfg(not(bootstrap))]
+    pub fn catch_unwind(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32;
+
+    /// For bootstrap only, see `catch_unwind`.
     #[rustc_nounwind]
+    #[cfg(bootstrap)]
     pub fn r#try(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32;
 
     /// Emits a `!nontemporal` store according to LLVM (see their docs).

panic_unwind/src/miri.rs

@@ -8,14 +8,14 @@ type Payload = Box<Box<dyn Any + Send>>;
 
 extern "Rust" {
     /// Miri-provided extern function to begin unwinding.
-    fn miri_start_panic(payload: *mut u8) -> !;
+    fn miri_start_unwind(payload: *mut u8) -> !;
 }
 
 pub unsafe fn panic(payload: Box<dyn Any + Send>) -> u32 {
-    // The payload we pass to `miri_start_panic` will be exactly the argument we get
+    // The payload we pass to `miri_start_unwind` will be exactly the argument we get
     // in `cleanup` below. So we just box it up once, to get something pointer-sized.
     let payload_box: Payload = Box::new(payload);
-    miri_start_panic(Box::into_raw(payload_box) as *mut u8)
+    miri_start_unwind(Box::into_raw(payload_box) as *mut u8)
 }
 
 pub unsafe fn cleanup(payload_box: *mut u8) -> Box<dyn Any + Send> {

std/src/panicking.rs

@@ -508,12 +508,12 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     // Access to the union's fields: this is `std` and we know that the `r#try`
     // intrinsic fills in the `r` or `p` union field based on its return value.
     //
-    // The call to `intrinsics::r#try` is made safe by:
+    // The call to `intrinsics::catch_unwind` is made safe by:
     // - `do_call`, the first argument, can be called with the initial `data_ptr`.
     // - `do_catch`, the second argument, can be called with the `data_ptr` as well.
     // See their safety preconditions for more information
     unsafe {
-        return if intrinsics::r#try(do_call::<F, R>, data_ptr, do_catch::<F, R>) == 0 {
+        return if intrinsics::catch_unwind(do_call::<F, R>, data_ptr, do_catch::<F, R>) == 0 {
             Ok(ManuallyDrop::into_inner(data.r))
         } else {
             Err(ManuallyDrop::into_inner(data.p))
@@ -540,7 +540,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     // Its must contains a valid `f` (type: F) value that can be use to fill
     // `data.r`.
     //
-    // This function cannot be marked as `unsafe` because `intrinsics::r#try`
+    // This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
     // expects normal function pointers.
     #[inline]
     fn do_call<F: FnOnce() -> R, R>(data: *mut u8) {
@@ -562,7 +562,7 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>>
     // Since this uses `cleanup` it also hinges on a correct implementation of
     // `__rustc_panic_cleanup`.
     //
-    // This function cannot be marked as `unsafe` because `intrinsics::r#try`
+    // This function cannot be marked as `unsafe` because `intrinsics::catch_unwind`
     // expects normal function pointers.
     #[inline]
     #[rustc_nounwind] // `intrinsic::r#try` requires catch fn to be nounwind