Auto merge of #92155 - m-ou-se:panic-fn, r=eddyb

Use panic() instead of panic!() in some places in core.

See https://github.com/rust-lang/rust/pull/92068 and https://github.com/rust-lang/rust/pull/92140.

This avoids the `panic!()` macro in a few potentially hot paths. This becomes more relevant when switching `core` to Rust 2021, as it'll avoid format_args!() and save some compilation time. (It doesn't make a huge difference, but still.) (Also the errors in const panic become slightly nicer.)

library/core/src/lib.rs

@@ -141,6 +141,7 @@
 #![feature(const_type_id)]
 #![feature(const_type_name)]
 #![feature(const_default_impls)]
+#![feature(core_panic)]
 #![feature(duration_consts_float)]
 #![feature(maybe_uninit_uninit_array)]
 #![feature(ptr_metadata)]

library/core/src/macros/mod.rs

@@ -589,9 +589,10 @@
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow_internal_unstable(core_panic)]
 macro_rules! unreachable {
     () => ({
-        $crate::panic!("internal error: entered unreachable code")
+        $crate::panicking::panic("internal error: entered unreachable code")
     });
     ($msg:expr $(,)?) => ({
         $crate::unreachable!("{}", $msg)
@@ -674,8 +675,9 @@
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
+#[allow_internal_unstable(core_panic)]
 macro_rules! unimplemented {
-    () => ($crate::panic!("not implemented"));
+    () => ($crate::panicking::panic("not implemented"));
     ($($arg:tt)+) => ($crate::panic!("not implemented: {}", $crate::format_args!($($arg)+)));
 }
 
@@ -735,8 +737,9 @@
 /// ```
 #[macro_export]
 #[stable(feature = "todo_macro", since = "1.40.0")]
+#[allow_internal_unstable(core_panic)]
 macro_rules! todo {
-    () => ($crate::panic!("not yet implemented"));
+    () => ($crate::panicking::panic("not yet implemented"));
     ($($arg:tt)+) => ($crate::panic!("not yet implemented: {}", $crate::format_args!($($arg)+)));
 }
 

library/core/src/option.rs

@@ -501,6 +501,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 use crate::iter::{FromIterator, FusedIterator, TrustedLen};
+use crate::panicking::{panic, panic_str};
 use crate::pin::Pin;
 use crate::{
     convert, hint, mem,
@@ -755,7 +756,7 @@ pub const fn expect(self, msg: &str) -> T {
     pub const fn unwrap(self) -> T {
         match self {
             Some(val) => val,
-            None => panic!("called `Option::unwrap()` on a `None` value"),
+            None => panic("called `Option::unwrap()` on a `None` value"),
         }
     }
 
@@ -1815,8 +1816,9 @@ pub const fn transpose(self) -> Result<Option<T>, E> {
 #[cfg_attr(feature = "panic_immediate_abort", inline)]
 #[cold]
 #[track_caller]
+#[rustc_const_unstable(feature = "const_option", issue = "67441")]
 const fn expect_failed(msg: &str) -> ! {
-    panic!("{}", msg)
+    panic_str(msg)
 }
 
 /////////////////////////////////////////////////////////////////////////////

src/test/mir-opt/issue_76432.test.SimplifyComparisonIntegral.diff

@@ -21,7 +21,7 @@
       let mut _19: *const T;               // in scope 0 at $DIR/issue_76432.rs:9:54: 9:68
       let mut _20: *const T;               // in scope 0 at $DIR/issue_76432.rs:9:70: 9:84
       let mut _21: *const T;               // in scope 0 at $DIR/issue_76432.rs:9:70: 9:84
-      let mut _22: !;                      // in scope 0 at $SRC_DIR/core/src/panic.rs:LL:COL
+      let mut _22: !;                      // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
       let mut _23: &[T; 3];                // in scope 0 at $DIR/issue_76432.rs:7:19: 7:29
       scope 1 {
           debug v => _2;                   // in scope 1 at $DIR/issue_76432.rs:7:9: 7:10
@@ -66,10 +66,10 @@
       }
   
       bb1: {
-          StorageLive(_22);                // scope 1 at $SRC_DIR/core/src/panic.rs:LL:COL
-          core::panicking::panic(const "internal error: entered unreachable code"); // scope 1 at $SRC_DIR/core/src/panic.rs:LL:COL
+          StorageLive(_22);                // scope 1 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+          core::panicking::panic(const "internal error: entered unreachable code"); // scope 1 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // mir::Constant
-                                           // + span: $SRC_DIR/core/src/panic.rs:LL:COL
+                                           // + span: $SRC_DIR/core/src/macros/mod.rs:LL:COL
                                            // + literal: Const { ty: fn(&'static str) -> ! {core::panicking::panic}, val: Value(Scalar(<ZST>)) }
                                            // ty::Const
                                            // + ty: &str

src/test/ui/consts/const-eval/const_panic.stderr

@@ -20,7 +20,7 @@ error[E0080]: evaluation of constant value failed
 LL | const Y: () = std::unreachable!();
    |               ^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:12:15
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `std::unreachable` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:15:15
@@ -28,7 +28,7 @@ error[E0080]: evaluation of constant value failed
 LL | const X: () = std::unimplemented!();
    |               ^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:15:15
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `std::unimplemented` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:18:15
@@ -68,7 +68,7 @@ error[E0080]: evaluation of constant value failed
 LL | const Y_CORE: () = core::unreachable!();
    |                    ^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic.rs:30:20
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `core::unreachable` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:33:20
@@ -76,7 +76,7 @@ error[E0080]: evaluation of constant value failed
 LL | const X_CORE: () = core::unimplemented!();
    |                    ^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic.rs:33:20
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `core::unimplemented` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic.rs:36:20

src/test/ui/consts/const-eval/const_panic_2021.stderr

@@ -20,7 +20,7 @@ error[E0080]: evaluation of constant value failed
 LL | const C: () = std::unreachable!();
    |               ^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic_2021.rs:12:15
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `std::unreachable` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_2021.rs:15:15
@@ -28,7 +28,7 @@ error[E0080]: evaluation of constant value failed
 LL | const D: () = std::unimplemented!();
    |               ^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic_2021.rs:15:15
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `std::unimplemented` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_2021.rs:18:15
@@ -60,7 +60,7 @@ error[E0080]: evaluation of constant value failed
 LL | const C_CORE: () = core::unreachable!();
    |                    ^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic_2021.rs:27:20
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `core::unreachable` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_2021.rs:30:20
@@ -68,7 +68,7 @@ error[E0080]: evaluation of constant value failed
 LL | const D_CORE: () = core::unimplemented!();
    |                    ^^^^^^^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic_2021.rs:30:20
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `core::unimplemented` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_2021.rs:33:20

src/test/ui/consts/const-eval/const_panic_libcore_bin.stderr

@@ -12,7 +12,7 @@ error[E0080]: evaluation of constant value failed
 LL | const Y: () = unreachable!();
    |               ^^^^^^^^^^^^^^ the evaluated program panicked at 'internal error: entered unreachable code', $DIR/const_panic_libcore_bin.rs:11:15
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `unreachable` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0080]: evaluation of constant value failed
   --> $DIR/const_panic_libcore_bin.rs:14:15
@@ -20,7 +20,7 @@ error[E0080]: evaluation of constant value failed
 LL | const X: () = unimplemented!();
    |               ^^^^^^^^^^^^^^^^ the evaluated program panicked at 'not implemented', $DIR/const_panic_libcore_bin.rs:14:15
    |
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `unimplemented` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 3 previous errors
 

src/tools/clippy/tests/ui/missing_panics_doc.stderr

@@ -42,7 +42,7 @@ note: first possible panic found here
    |
 LL |     todo!()
    |     ^^^^^^^
-   = note: this error originates in the macro `$crate::panic::panic_2015` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `todo` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: docs for function which may panic missing `# Panics` section
   --> $DIR/missing_panics_doc.rs:22:1