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Explicitly export core and std macros #139493

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14db115
Explicitly export core and std macros
Voultapher Apr 7, 2025
2ac3f32
Apply review comments
Voultapher Apr 8, 2025
6c9b632
Fix formatting tidy issues
Voultapher Apr 8, 2025
3699f8d
Special case vec macro
Voultapher Apr 8, 2025
25f46fb
Explicitly import format_args_nl
Voultapher Apr 9, 2025
9eaeba8
Exclude panic and env namespaces from prelude
Voultapher Apr 9, 2025
114947e
Explicitly use std panic over core panic
Voultapher Apr 11, 2025
24c0ac1
Remove #[macro_use] std/core from tests
Voultapher Apr 11, 2025
87be0d7
Bless straight forward UI test changes
Voultapher Apr 11, 2025
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2 changes: 1 addition & 1 deletion compiler/rustc_builtin_macros/src/standard_library_imports.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -43,7 +43,7 @@ pub fn inject(

let item = cx.item(
span,
thin_vec![cx.attr_word(sym::macro_use, span)],
ast::AttrVec::new(),
ast::ItemKind::ExternCrate(None, Ident::new(name, ident_span)),
);

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53 changes: 50 additions & 3 deletions library/core/src/prelude/v1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -61,11 +61,17 @@ pub use crate::hash::macros::Hash;
#[allow(deprecated)]
#[doc(no_inline)]
pub use crate::{
assert, cfg, column, compile_error, concat, concat_idents, env, file, format_args,
format_args_nl, include, include_bytes, include_str, line, log_syntax, module_path, option_env,
stringify, trace_macros,
assert, assert_eq, assert_ne, cfg, column, compile_error, concat, debug_assert, debug_assert_eq, debug_assert_ne, env, file, format_args, include, include_bytes, include_str, line, matches, module_path, option_env, panic, stringify, todo, r#try, unimplemented, unreachable, write, writeln,
};

#[unstable(feature = "ub_checks", issue = "none")]
#[doc(no_inline)]
pub use crate::assert_unsafe_precondition;

#[unstable(feature = "cfg_match", issue = "115585")]
#[doc(no_inline)]
pub use crate::cfg_match;

#[unstable(
feature = "concat_bytes",
issue = "87555",
Expand All @@ -74,6 +80,47 @@ pub use crate::{
#[doc(no_inline)]
pub use crate::concat_bytes;

#[unstable(
feature = "concat_idents",
issue = "29599",
reason = "`concat_idents` is not stable enough for use and is subject to change"
)]
#[doc(no_inline)]
pub use crate::concat_idents;

#[unstable(feature = "const_format_args", issue = "none")]
#[doc(no_inline)]
pub use crate::const_format_args;

#[unstable(
feature = "format_args_nl",
issue = "none",
reason = "`format_args_nl` is only for internal \
language use and is subject to change"
)]
#[doc(no_inline)]
pub use crate::format_args_nl;

#[unstable(
feature = "log_syntax",
issue = "29598",
reason = "`log_syntax!` is not stable enough for use and is subject to change"
)]
#[doc(no_inline)]
pub use crate::log_syntax;

#[unstable(feature = "pattern_type_macro", issue = "123646")]
#[doc(no_inline)]
pub use crate::pattern_type;

#[unstable(
feature = "trace_macros",
issue = "29598",
reason = "`trace_macros` is not stable enough for use and is subject to change"
)]
#[doc(no_inline)]
pub use crate::trace_macros;

// Do not `doc(no_inline)` so that they become doc items on their own
// (no public module for them to be re-exported from).
#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
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4 changes: 3 additions & 1 deletion library/proc_macro/src/bridge/symbol.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,8 +12,10 @@
use std::cell::RefCell;
use std::num::NonZero;
use std::str;
use std::fmt;

use super::*;
// Explicit import to avoid macro namespace collision.
use super::{arena, client, DecodeMut, Encode, fxhash, Mark, Marked, Reader, server, Unmark, Writer};
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What collision is this? Is this something that user code is likely to encounter?

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Here is the error that I get when not making this change:

error[E0659]: `panic` is ambiguous
   --> library/proc_macro/src/bridge/symbol.rs:41:17
    |
41  |                 panic!("`{}` cannot be a raw identifier", string);
    |                 ^^^^^ ambiguous name
    |
    = note: ambiguous because of a conflict between a name from a glob import and an outer scope during import or macro resolution
note: `panic` could refer to the macro imported here
   --> library/proc_macro/src/bridge/symbol.rs:19:5
    |
19  | use super::*;
    |     ^^^^^^^^
    = help: consider adding an explicit import of `panic` to disambiguate
    = help: or use `self::panic` to refer to this macro unambiguously
note: `panic` could also refer to the macro defined here
   --> /rust/library/std/src/prelude/mod.rs:157:13
    |
157 |     pub use super::v1::*;
    |             ^^^^^^^^^

My reasoning is a follows, this special proc macro is built together with std which gives access to std via super, causing the import ambiguity. I don't think this is an issue for user code since normal crates can't access std via super - I checked - and I assume normal proc macros can't either, but I'm no expert in that area.


/// Handle for a symbol string stored within the Interner.
#[derive(Copy, Clone, PartialEq, Eq, Hash)]
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55 changes: 51 additions & 4 deletions library/std/src/prelude/v1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -43,16 +43,26 @@ pub use crate::option::Option::{self, None, Some};
#[doc(no_inline)]
pub use crate::result::Result::{self, Err, Ok};

// Re-exported built-in macros
// Re-exported built-in macros and traits
#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
#[allow(deprecated)]
#[doc(no_inline)]
pub use core::prelude::v1::{
assert, cfg, column, compile_error, concat, concat_idents, env, file, format_args,
format_args_nl, include, include_bytes, include_str, line, log_syntax, module_path, option_env,
stringify, trace_macros, Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd,
assert, assert_eq, assert_ne, cfg, column, compile_error, concat, debug_assert, debug_assert_eq, debug_assert_ne, env, file, format_args, include, include_bytes, include_str, line, matches,
module_path, option_env, panic, stringify, todo, r#try, unimplemented, unreachable, write,
writeln, Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd,
};

#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
#[doc(no_inline)]
pub use crate::{
dbg, eprint, eprintln, format, is_x86_feature_detected, print, println, thread_local, vec,
};

#[unstable(feature = "cfg_match", issue = "115585")]
#[doc(no_inline)]
pub use core::prelude::v1::cfg_match;

#[unstable(
feature = "concat_bytes",
issue = "87555",
Expand All @@ -61,6 +71,43 @@ pub use core::prelude::v1::{
#[doc(no_inline)]
pub use core::prelude::v1::concat_bytes;

#[unstable(
feature = "concat_idents",
issue = "29599",
reason = "`concat_idents` is not stable enough for use and is subject to change"
)]
#[doc(no_inline)]
pub use core::prelude::v1::concat_idents;

#[unstable(feature = "const_format_args", issue = "none")]
#[doc(no_inline)]
pub use core::prelude::v1::const_format_args;

#[unstable(
feature = "format_args_nl",
issue = "none",
reason = "`format_args_nl` is only for internal \
language use and is subject to change"
)]
#[doc(no_inline)]
pub use core::prelude::v1::format_args_nl;

#[unstable(
feature = "log_syntax",
issue = "29598",
reason = "`log_syntax!` is not stable enough for use and is subject to change"
)]
#[doc(no_inline)]
pub use core::prelude::v1::log_syntax;

#[unstable(
feature = "trace_macros",
issue = "29598",
reason = "`trace_macros` is not stable enough for use and is subject to change"
)]
#[doc(no_inline)]
pub use core::prelude::v1::trace_macros;

// Do not `doc(no_inline)` so that they become doc items on their own
// (no public module for them to be re-exported from).
#[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
Expand Down
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