Qualify panic! as core::panic! in non-built-in core macros

Otherwise code like this

    #![no_implicit_prelude]

    fn main() {
        ::std::todo!();
        ::std::unimplemented!();
    }

will fail to compile, which is unfortunate and presumably unintended.

This changes many invocations of `panic!` in a `macro_rules!` definition
to invocations of `$crate::panic!`, which makes the invocations hygienic.

Note that this does not make the built-in macro `assert!` hygienic.

Author: camelid

library/core/src/macros/mod.rs

@@ -44,7 +44,7 @@ macro_rules! assert_eq {
                     // The reborrows below are intentional. Without them, the stack slot for the
                     // borrow is initialized even before the values are compared, leading to a
                     // noticeable slow down.
-                    panic!(r#"assertion failed: `(left == right)`
+                    $crate::panic!(r#"assertion failed: `(left == right)`
   left: `{:?}`,
  right: `{:?}`"#, &*left_val, &*right_val)
                 }
@@ -58,7 +58,7 @@ macro_rules! assert_eq {
                     // The reborrows below are intentional. Without them, the stack slot for the
                     // borrow is initialized even before the values are compared, leading to a
                     // noticeable slow down.
-                    panic!(r#"assertion failed: `(left == right)`
+                    $crate::panic!(r#"assertion failed: `(left == right)`
   left: `{:?}`,
  right: `{:?}`: {}"#, &*left_val, &*right_val,
                            $crate::format_args!($($arg)+))
@@ -95,7 +95,7 @@ macro_rules! assert_ne {
                     // The reborrows below are intentional. Without them, the stack slot for the
                     // borrow is initialized even before the values are compared, leading to a
                     // noticeable slow down.
-                    panic!(r#"assertion failed: `(left != right)`
+                    $crate::panic!(r#"assertion failed: `(left != right)`
   left: `{:?}`,
  right: `{:?}`"#, &*left_val, &*right_val)
                 }
@@ -109,7 +109,7 @@ macro_rules! assert_ne {
                     // The reborrows below are intentional. Without them, the stack slot for the
                     // borrow is initialized even before the values are compared, leading to a
                     // noticeable slow down.
-                    panic!(r#"assertion failed: `(left != right)`
+                    $crate::panic!(r#"assertion failed: `(left != right)`
   left: `{:?}`,
  right: `{:?}`: {}"#, &*left_val, &*right_val,
                            $crate::format_args!($($arg)+))
@@ -466,7 +466,7 @@ macro_rules! writeln {
 ///
 /// # Panics
 ///
-/// This will always [`panic!`]
+/// This will always [`panic!`].
 ///
 /// # Examples
 ///
@@ -500,13 +500,13 @@ macro_rules! writeln {
 #[stable(feature = "rust1", since = "1.0.0")]
 macro_rules! unreachable {
     () => ({
-        panic!("internal error: entered unreachable code")
+        $crate::panic!("internal error: entered unreachable code")
     });
     ($msg:expr $(,)?) => ({
         $crate::unreachable!("{}", $msg)
     });
     ($fmt:expr, $($arg:tt)*) => ({
-        panic!($crate::concat!("internal error: entered unreachable code: ", $fmt), $($arg)*)
+        $crate::panic!($crate::concat!("internal error: entered unreachable code: ", $fmt), $($arg)*)
     });
 }
 
@@ -584,8 +584,8 @@ macro_rules! unreachable {
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
 macro_rules! unimplemented {
-    () => (panic!("not implemented"));
-    ($($arg:tt)+) => (panic!("not implemented: {}", $crate::format_args!($($arg)+)));
+    () => ($crate::panic!("not implemented"));
+    ($($arg:tt)+) => ($crate::panic!("not implemented: {}", $crate::format_args!($($arg)+)));
 }
 
 /// Indicates unfinished code.
@@ -645,8 +645,8 @@ macro_rules! unimplemented {
 #[macro_export]
 #[stable(feature = "todo_macro", since = "1.40.0")]
 macro_rules! todo {
-    () => (panic!("not yet implemented"));
-    ($($arg:tt)+) => (panic!("not yet implemented: {}", $crate::format_args!($($arg)+)));
+    () => ($crate::panic!("not yet implemented"));
+    ($($arg:tt)+) => ($crate::panic!("not yet implemented: {}", $crate::format_args!($($arg)+)));
 }
 
 /// Definitions of built-in macros.

src/test/mir-opt/issue_73223.main.PreCodegen.32bit.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/std/src/macros.rs:LL:COL
+      let mut _22: !;                      // in scope 0 at $SRC_DIR/core/src/macros/mod.rs:LL:COL
       scope 1 {
           debug v => _2;                   // in scope 1 at $DIR/issue_76432.rs:7:9: 7:10
           let _13: &T;                     // in scope 1 at $DIR/issue_76432.rs:9:10: 9:16
@@ -64,11 +64,11 @@
       }
 
       bb1: {
-          StorageLive(_22);                // scope 1 at $SRC_DIR/std/src/macros.rs:LL:COL
-          begin_panic::<&str>(const "internal error: entered unreachable code"); // scope 1 at $SRC_DIR/std/src/macros.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/std/src/macros.rs:LL:COL
-                                           // + literal: Const { ty: fn(&str) -> ! {std::rt::begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
+                                           // + 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
                                            // + val: Value(Slice { data: Allocation { bytes: [105, 110, 116, 101, 114, 110, 97, 108, 32, 101, 114, 114, 111, 114, 58, 32, 101, 110, 116, 101, 114, 101, 100, 32, 117, 110, 114, 101, 97, 99, 104, 97, 98, 108, 101, 32, 99, 111, 100, 101], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [1099511627775], len: Size { raw: 40 } }, size: Size { raw: 40 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 40 })

src/test/mir-opt/issue_73223.main.PreCodegen.64bit.diff

@@ -1,7 +1,7 @@
 #![feature(decl_macro)]
 
 mod foo {
-    pub macro m() { Vec::new(); ().clone() }
+    pub macro m() { Vec::<i32>::new(); ().clone() }
     fn f() { ::bar::m!(); }
 }
 
@@ -13,7 +13,7 @@ mod bar {
     }
     fn f() {
         ::foo::m!();
-        assert_eq!(0, 0); //~ ERROR cannot find macro `panic` in this scope
+        assert!(true); //~ ERROR cannot find macro `panic` in this scope
     }
 }
 

src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.32bit.diff

@@ -1,8 +1,8 @@
 error: cannot find macro `panic` in this scope
   --> $DIR/no_implicit_prelude.rs:16:9
    |
-LL |         assert_eq!(0, 0);
-   |         ^^^^^^^^^^^^^^^^^
+LL |         assert!(true);
+   |         ^^^^^^^^^^^^^^
    |
    = note: consider importing one of these items:
            core::panic

src/test/mir-opt/issue_73223.main.SimplifyArmIdentity.64bit.diff

@@ -0,0 +1,11 @@
+// build-pass
+
+#![no_implicit_prelude]
+
+fn main() {
+    ::std::panic!();
+    ::std::todo!();
+    ::std::unimplemented!();
+    ::std::assert_eq!(0, 0);
+    ::std::dbg!(123);
+}