Rollup merge of #63056 - petrochenkov:macstd2, r=alexcrichton

Give built-in macros stable addresses in the standard library

Continuation of https://github.com/rust-lang/rust/pull/62086.

Derive macros corresponding to traits from libcore are now available through the same paths as those traits:
- `Clone` - `{core,std}::clone::Clone`
- `PartialEq` - `{core,std}::cmp::PartialEq`
- `Eq` - `{core,std}::cmp::Eq`
- `PartialOrd` - `{core,std}::cmp::PartialOrd`
- `Ord` - `{core,std}::cmp::Ord`
- `Default` - `{core,std}::default::Default`
- `Debug` - `{core,std}::fmt::Debug`
- `Hash` - `{core,std}::hash::Hash`
- `Copy` - `{core,std}::marker::Copy`

Fn-like built-in macros are now available through libcore and libstd's root module, by analogy with non-builtin macros defined by libcore and libstd:
```rust
{core,std}::{
    __rust_unstable_column,
    asm,
    assert,
    cfg,
    column,
    compile_error,
    concat,
    concat_idents,
    env,
    file,
    format_args,
    format_args_nl,
    global_asm,
    include,
    include_bytes,
    include_str,
    line,
    log_syntax,
    module_path,
    option_env,
    stringify,
    trace_macros,
}
```

Derive macros without a corresponding trait in libcore or libstd are still available only through prelude (also see https://github.com/rust-lang/rust/pull/62507).
Attribute macros also keep being available only through prelude, mostly because they don't have an existing practice to follow. An advice from the library team on their eventual placement would be appreciated.
```rust
    RustcDecodable,
    RustcEncodable,
    bench,
    global_allocator,
    test,
    test_case,
```

r? @alexcrichton

1 files changed, 30 insertions, 21 deletions

diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index 54abf72d307..e03626fb7f5 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -326,16 +326,6 @@ use prelude::v1::*;
 // Access to Bencher, etc.
 #[cfg(test)] extern crate test;
 
-// Re-export a few macros from core
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::{assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne};
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::{unreachable, unimplemented, write, writeln, todo};
-// FIXME: change this to `#[allow(deprecated)]` when we update nightly compiler.
-#[allow(deprecated_in_future)]
-#[stable(feature = "rust1", since = "1.0.0")]
-pub use core::r#try;
-
 #[allow(unused_imports)] // macros from `alloc` are not used on all platforms
 #[macro_use]
 extern crate alloc as alloc_crate;
@@ -520,33 +510,52 @@ mod std_detect;
 #[cfg(not(test))]
 pub use std_detect::detect;
 
-// Document built-in macros in the crate root for consistency with libcore and existing tradition.
-// FIXME: Attribute and derive macros are not reexported because rustdoc renders them
-// as reexports rather than as macros, and that's not what we want.
-#[cfg(rustdoc)]
+// Re-export macros defined in libcore.
+#[stable(feature = "rust1", since = "1.0.0")]
+#[allow(deprecated_in_future)]
+pub use core::{
+    // Stable
+    assert_eq,
+    assert_ne,
+    debug_assert_eq,
+    debug_assert_ne,
+    debug_assert,
+    r#try,
+    unimplemented,
+    unreachable,
+    write,
+    writeln,
+    // Unstable
+    todo,
+};
+
+// Re-export built-in macros defined through libcore.
+#[cfg(not(bootstrap))]
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]
-pub use crate::prelude::v1::{
-    __rust_unstable_column,
-    asm,
+pub use core::{
+    // Stable
     assert,
     cfg,
     column,
     compile_error,
     concat,
-    concat_idents,
     env,
     file,
     format_args,
-    format_args_nl,
-    global_asm,
     include,
     include_bytes,
     include_str,
     line,
-    log_syntax,
     module_path,
     option_env,
     stringify,
+    // Unstable
+    __rust_unstable_column,
+    asm,
+    concat_idents,
+    format_args_nl,
+    global_asm,
+    log_syntax,
     trace_macros,
 };