Rollup merge of #61629 - petrochenkov:stdmac, r=alexcrichton

Hygienize macros in the standard library

Same as https://github.com/rust-lang/rust/pull/55597, but for all macros in the standard library.
Nested macro calls will now call what they are intended to call rather than whatever is in the closest scope at call site.
Technically this is a breaking change, so crater run would probably be useful.

---

One exception that is not hygienized is calls to `panic!(...)`.
Macros defined in libcore do not want to call `core::panic`.
What they really want to call is either `std::panic` or `core::panic` depending on `no_std` settings.
EDIT: After some thought, recursive calls to `panic` from `panic` itself probably do want to use `$crate` (UPDATE: done).

Calling `std::panic` from macros defined in std and "whatever `panic` is in scope" from macros defined in libcore is probably even worse than always calling "whatever `panic` is in scope", so I kept the existing code.

The only way to do the std/core switch correctly that I'm aware of is to define a built-in panic macro that would dispatch to `std::panic` or `core::panic` using compiler magic.
Then standard library macros could delegate to this built-in macro.
The macro could be named `panic` too, that would fix https://github.com/rust-lang/rust/issues/61567.
(This PR doesn't do that.)

---
cc https://github.com/rust-lang/rust/issues/56389
cc https://github.com/rust-lang/rust/issues/61567
Fixes https://github.com/rust-lang/rust/issues/61699
r? @alexcrichton

1 files changed, 8 insertions, 8 deletions

diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index ef7179f0b6f..ef1b549d1dc 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -56,13 +56,13 @@
 #[allow_internal_unstable(__rust_unstable_column, libstd_sys_internals)]
 macro_rules! panic {
     () => ({
-        panic!("explicit panic")
+        $crate::panic!("explicit panic")
     });
     ($msg:expr) => ({
         $crate::rt::begin_panic($msg, &(file!(), line!(), __rust_unstable_column!()))
     });
     ($msg:expr,) => ({
-        panic!($msg)
+        $crate::panic!($msg)
     });
     ($fmt:expr, $($arg:tt)+) => ({
         $crate::rt::begin_panic_fmt(&format_args!($fmt, $($arg)+),
@@ -145,7 +145,7 @@ macro_rules! print {
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow_internal_unstable(print_internals, format_args_nl)]
 macro_rules! println {
-    () => (print!("\n"));
+    () => ($crate::print!("\n"));
     ($($arg:tt)*) => ({
         $crate::io::_print(format_args_nl!($($arg)*));
     })
@@ -204,7 +204,7 @@ macro_rules! eprint {
 #[stable(feature = "eprint", since = "1.19.0")]
 #[allow_internal_unstable(print_internals, format_args_nl)]
 macro_rules! eprintln {
-    () => (eprint!("\n"));
+    () => ($crate::eprint!("\n"));
     ($($arg:tt)*) => ({
         $crate::io::_eprint(format_args_nl!($($arg)*));
     })
@@ -337,23 +337,23 @@ macro_rules! eprintln {
 #[stable(feature = "dbg_macro", since = "1.32.0")]
 macro_rules! dbg {
     () => {
-        eprintln!("[{}:{}]", file!(), line!());
+        $crate::eprintln!("[{}:{}]", file!(), line!());
     };
     ($val:expr) => {
         // Use of `match` here is intentional because it affects the lifetimes
         // of temporaries - https://stackoverflow.com/a/48732525/1063961
         match $val {
             tmp => {
-                eprintln!("[{}:{}] {} = {:#?}",
+                $crate::eprintln!("[{}:{}] {} = {:#?}",
                     file!(), line!(), stringify!($val), &tmp);
                 tmp
             }
         }
     };
     // Trailing comma with single argument is ignored
-    ($val:expr,) => { dbg!($val) };
+    ($val:expr,) => { $crate::dbg!($val) };
     ($($val:expr),+ $(,)?) => {
-        ($(dbg!($val)),+,)
+        ($($crate::dbg!($val)),+,)
     };
 }