Explicitly export core and std macros

Currently all core and std macros are automatically added to the prelude
via #[macro_use]. However a situation arose where we want to add a new macro
`assert_matches` but don't want to pull it into the standard prelude for
compatibility reasons. By explicitly exporting the macros found in the core and
std crates we get to decide on a per macro basis and can later add them via
the rust_20xx preludes.

Author: Voultapher

compiler/rustc_builtin_macros/src/standard_library_imports.rs

@@ -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)),
     );
 

library/core/src/prelude/v1.rs

@@ -60,11 +60,17 @@ pub use crate::hash::macros::Hash;
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
 #[doc(no_inline)]
 pub use crate::{
-    assert, cfg, column, compile_error, concat, 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",
@@ -73,6 +79,47 @@ 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")]

library/proc_macro/src/bridge/symbol.rs

@@ -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};
 
 /// Handle for a symbol string stored within the Interner.
 #[derive(Copy, Clone, PartialEq, Eq, Hash)]

library/std/src/prelude/v1.rs

@@ -43,15 +43,25 @@ 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")]
 #[doc(no_inline)]
 pub use core::prelude::v1::{
-    assert, cfg, column, compile_error, concat, 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",
@@ -60,6 +70,43 @@ 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")]