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Rollup merge of rust-lang#61629 - petrochenkov:stdmac, r=alexcrichton
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Hygienize macros in the standard library

Same as rust-lang#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 rust-lang#61567.
(This PR doesn't do that.)

---
cc rust-lang#56389
cc rust-lang#61567
Fixes rust-lang#61699
r? @alexcrichton
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Centril authored Jun 12, 2019
2 parents 648a529 + eb09daa commit 55df67d
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Showing 7 changed files with 26 additions and 47 deletions.
2 changes: 1 addition & 1 deletion src/liballoc/macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ macro_rules! vec {
($($x:expr),*) => (
<[_]>::into_vec(box [$($x),*])
);
($($x:expr,)*) => (vec![$($x),*])
($($x:expr,)*) => ($crate::vec![$($x),*])
}

// HACK(japaric): with cfg(test) the inherent `[T]::into_vec` method, which is
Expand Down
22 changes: 11 additions & 11 deletions src/libcore/macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,13 @@
#[stable(feature = "core", since = "1.6.0")]
macro_rules! panic {
() => (
panic!("explicit panic")
$crate::panic!("explicit panic")
);
($msg:expr) => ({
$crate::panicking::panic(&($msg, file!(), line!(), __rust_unstable_column!()))
});
($msg:expr,) => (
panic!($msg)
$crate::panic!($msg)
);
($fmt:expr, $($arg:tt)+) => ({
$crate::panicking::panic_fmt(format_args!($fmt, $($arg)*),
Expand Down Expand Up @@ -58,7 +58,7 @@ macro_rules! assert_eq {
}
});
($left:expr, $right:expr,) => ({
assert_eq!($left, $right)
$crate::assert_eq!($left, $right)
});
($left:expr, $right:expr, $($arg:tt)+) => ({
match (&($left), &($right)) {
Expand Down Expand Up @@ -115,7 +115,7 @@ macro_rules! assert_ne {
}
});
($left:expr, $right:expr,) => {
assert_ne!($left, $right)
$crate::assert_ne!($left, $right)
};
($left:expr, $right:expr, $($arg:tt)+) => ({
match (&($left), &($right)) {
Expand Down Expand Up @@ -208,7 +208,7 @@ macro_rules! debug_assert {
#[macro_export]
#[stable(feature = "rust1", since = "1.0.0")]
macro_rules! debug_assert_eq {
($($arg:tt)*) => (if cfg!(debug_assertions) { assert_eq!($($arg)*); })
($($arg:tt)*) => (if cfg!(debug_assertions) { $crate::assert_eq!($($arg)*); })
}

/// Asserts that two expressions are not equal to each other.
Expand All @@ -235,7 +235,7 @@ macro_rules! debug_assert_eq {
#[macro_export]
#[stable(feature = "assert_ne", since = "1.13.0")]
macro_rules! debug_assert_ne {
($($arg:tt)*) => (if cfg!(debug_assertions) { assert_ne!($($arg)*); })
($($arg:tt)*) => (if cfg!(debug_assertions) { $crate::assert_ne!($($arg)*); })
}

/// Unwraps a result or propagates its error.
Expand Down Expand Up @@ -310,7 +310,7 @@ macro_rules! r#try {
return $crate::result::Result::Err($crate::convert::From::from(err))
}
});
($expr:expr,) => (r#try!($expr));
($expr:expr,) => ($crate::r#try!($expr));
}

/// Writes formatted data into a buffer.
Expand Down Expand Up @@ -425,10 +425,10 @@ macro_rules! write {
#[allow_internal_unstable(format_args_nl)]
macro_rules! writeln {
($dst:expr) => (
write!($dst, "\n")
$crate::write!($dst, "\n")
);
($dst:expr,) => (
writeln!($dst)
$crate::writeln!($dst)
);
($dst:expr, $($arg:tt)*) => (
$dst.write_fmt(format_args_nl!($($arg)*))
Expand Down Expand Up @@ -494,10 +494,10 @@ macro_rules! unreachable {
panic!("internal error: entered unreachable code")
});
($msg:expr) => ({
unreachable!("{}", $msg)
$crate::unreachable!("{}", $msg)
});
($msg:expr,) => ({
unreachable!($msg)
$crate::unreachable!($msg)
});
($fmt:expr, $($arg:tt)*) => ({
panic!(concat!("internal error: entered unreachable code: ", $fmt), $($arg)*)
Expand Down
16 changes: 8 additions & 8 deletions src/libstd/macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -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)+),
Expand Down Expand Up @@ -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)*) => ({
$crate::io::_print(format_args_nl!($($arg)*));
})
Expand Down Expand Up @@ -204,7 +204,7 @@ macro_rules! eprint {
#[stable(feature = "eprint", since = "1.19.0")]
#[allow_internal_unstable(print_internals, format_args_nl)]
macro_rules! eprintln {
() => (eprint!("\n"));
() => ($crate::eprint!("\n"));
($($arg:tt)*) => ({
$crate::io::_eprint(format_args_nl!($($arg)*));
})
Expand Down Expand Up @@ -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)),+,)
};
}

Expand Down
2 changes: 1 addition & 1 deletion src/test/ui/hygiene/no_implicit_prelude.rs
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ mod bar {
}
fn f() {
::foo::m!();
println!(); //~ ERROR cannot find macro `print!` in this scope
assert_eq!(0, 0); //~ ERROR cannot find macro `panic!` in this scope
}
}

Expand Down
6 changes: 3 additions & 3 deletions src/test/ui/hygiene/no_implicit_prelude.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -7,11 +7,11 @@ LL | fn f() { ::bar::m!(); }
LL | Vec::new();
| ^^^ use of undeclared type or module `Vec`

error: cannot find macro `print!` in this scope
error: cannot find macro `panic!` in this scope
--> $DIR/no_implicit_prelude.rs:16:9
|
LL | println!();
| ^^^^^^^^^^^
LL | assert_eq!(0, 0);
| ^^^^^^^^^^^^^^^^^
|
= help: have you added the `#[macro_use]` on the module/import?
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
Expand Down
1 change: 0 additions & 1 deletion src/test/ui/imports/local-modularized-tricky-fail-1.rs
Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,6 @@ mod inner2 {

fn main() {
panic!(); //~ ERROR `panic` is ambiguous
//~| ERROR `panic` is ambiguous
}

mod inner3 {
Expand Down
24 changes: 2 additions & 22 deletions src/test/ui/imports/local-modularized-tricky-fail-1.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ LL | use inner1::*;
= help: consider adding an explicit import of `exported` to disambiguate

error[E0659]: `include` is ambiguous (macro-expanded name vs less macro-expanded name from outer scope during import/macro resolution)
--> $DIR/local-modularized-tricky-fail-1.rs:47:1
--> $DIR/local-modularized-tricky-fail-1.rs:46:1
|
LL | include!();
| ^^^^^^^ ambiguous name
Expand Down Expand Up @@ -59,26 +59,6 @@ LL | define_panic!();
| ---------------- in this macro invocation
= help: use `crate::panic` to refer to this macro unambiguously

error[E0659]: `panic` is ambiguous (macro-expanded name vs less macro-expanded name from outer scope during import/macro resolution)
--> $DIR/local-modularized-tricky-fail-1.rs:35:5
|
LL | panic!();
| ^^^^^^^^^ ambiguous name
|
= note: `panic` could refer to a macro from prelude
note: `panic` could also refer to the macro defined here
--> $DIR/local-modularized-tricky-fail-1.rs:11:5
|
LL | / macro_rules! panic {
LL | | () => ()
LL | | }
| |_____^
...
LL | define_panic!();
| ---------------- in this macro invocation
= help: use `crate::panic` to refer to this macro unambiguously
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)

error: aborting due to 4 previous errors
error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0659`.

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