Rollup merge of #52581 - petrochenkov:bmacrodoc, r=alexcrichton

Avoid using `#[macro_export]` for documenting builtin macros

Use a special `rustc_*` attribute instead.

cc https://github.com/rust-lang/rust/pull/52234

5 files changed, 43 insertions, 58 deletions

diff --git a/src/libcore/macros.rs b/src/libcore/macros.rs
index c830c22ee5f..83f9dfea8f2 100644
--- a/src/libcore/macros.rs
+++ b/src/libcore/macros.rs
@@ -543,6 +543,7 @@ macro_rules! unimplemented {
 /// into libsyntax itself.
 ///
 /// For more information, see documentation for `std`'s macros.
+#[cfg(dox)]
 mod builtin {
 
     /// Unconditionally causes compilation to fail with the given error message when encountered.
@@ -551,8 +552,7 @@ mod builtin {
     ///
     /// [`std::compile_error!`]: ../std/macro.compile_error.html
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! compile_error {
         ($msg:expr) => ({ /* compiler built-in */ });
         ($msg:expr,) => ({ /* compiler built-in */ });
@@ -564,8 +564,7 @@ mod builtin {
     ///
     /// [`std::format_args!`]: ../std/macro.format_args.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! format_args {
         ($fmt:expr) => ({ /* compiler built-in */ });
         ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ });
@@ -577,8 +576,7 @@ mod builtin {
     ///
     /// [`std::env!`]: ../std/macro.env.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! env {
         ($name:expr) => ({ /* compiler built-in */ });
         ($name:expr,) => ({ /* compiler built-in */ });
@@ -590,8 +588,7 @@ mod builtin {
     ///
     /// [`std::option_env!`]: ../std/macro.option_env.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! option_env {
         ($name:expr) => ({ /* compiler built-in */ });
         ($name:expr,) => ({ /* compiler built-in */ });
@@ -603,8 +600,7 @@ mod builtin {
     ///
     /// [`std::concat_idents!`]: ../std/macro.concat_idents.html
     #[unstable(feature = "concat_idents_macro", issue = "29599")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! concat_idents {
         ($($e:ident),+) => ({ /* compiler built-in */ });
         ($($e:ident,)+) => ({ /* compiler built-in */ });
@@ -616,8 +612,7 @@ mod builtin {
     ///
     /// [`std::concat!`]: ../std/macro.concat.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! concat {
         ($($e:expr),*) => ({ /* compiler built-in */ });
         ($($e:expr,)*) => ({ /* compiler built-in */ });
@@ -629,8 +624,7 @@ mod builtin {
     ///
     /// [`std::line!`]: ../std/macro.line.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! line { () => ({ /* compiler built-in */ }) }
 
     /// A macro which expands to the column number on which it was invoked.
@@ -639,8 +633,7 @@ mod builtin {
     ///
     /// [`std::column!`]: ../std/macro.column.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! column { () => ({ /* compiler built-in */ }) }
 
     /// A macro which expands to the file name from which it was invoked.
@@ -649,8 +642,7 @@ mod builtin {
     ///
     /// [`std::file!`]: ../std/macro.file.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! file { () => ({ /* compiler built-in */ }) }
 
     /// A macro which stringifies its arguments.
@@ -659,8 +651,7 @@ mod builtin {
     ///
     /// [`std::stringify!`]: ../std/macro.stringify.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! stringify { ($($t:tt)*) => ({ /* compiler built-in */ }) }
 
     /// Includes a utf8-encoded file as a string.
@@ -669,8 +660,7 @@ mod builtin {
     ///
     /// [`std::include_str!`]: ../std/macro.include_str.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! include_str {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -682,8 +672,7 @@ mod builtin {
     ///
     /// [`std::include_bytes!`]: ../std/macro.include_bytes.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! include_bytes {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -695,8 +684,7 @@ mod builtin {
     ///
     /// [`std::module_path!`]: ../std/macro.module_path.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! module_path { () => ({ /* compiler built-in */ }) }
 
     /// Boolean evaluation of configuration flags, at compile-time.
@@ -705,8 +693,7 @@ mod builtin {
     ///
     /// [`std::cfg!`]: ../std/macro.cfg.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! cfg { ($($cfg:tt)*) => ({ /* compiler built-in */ }) }
 
     /// Parse a file as an expression or an item according to the context.
@@ -715,8 +702,7 @@ mod builtin {
     ///
     /// [`std::include!`]: ../std/macro.include.html
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
-    #[cfg(dox)]
+    #[rustc_doc_only_macro]
     macro_rules! include {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -727,9 +713,8 @@ mod builtin {
     /// For more information, see the documentation for [`std::assert!`].
     ///
     /// [`std::assert!`]: ../std/macro.assert.html
-    #[macro_export]
+    #[rustc_doc_only_macro]
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[cfg(dox)]
     macro_rules! assert {
         ($cond:expr) => ({ /* compiler built-in */ });
         ($cond:expr,) => ({ /* compiler built-in */ });
diff --git a/src/librustc/hir/lowering.rs b/src/librustc/hir/lowering.rs
index 99db718bdf8..8e27a9914f4 100644
--- a/src/librustc/hir/lowering.rs
+++ b/src/librustc/hir/lowering.rs
@@ -3191,7 +3191,8 @@ impl<'a> LoweringContext<'a> {
         let mut vis = self.lower_visibility(&i.vis, None);
         let attrs = self.lower_attrs(&i.attrs);
         if let ItemKind::MacroDef(ref def) = i.node {
-            if !def.legacy || attr::contains_name(&i.attrs, "macro_export") {
+            if !def.legacy || attr::contains_name(&i.attrs, "macro_export") ||
+                              attr::contains_name(&i.attrs, "rustc_doc_only_macro") {
                 let body = self.lower_token_stream(def.stream());
                 self.exported_macros.push(hir::MacroDef {
                     name,
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 77521db835b..54cf82a19b4 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1273,15 +1273,13 @@ fn macro_resolve(cx: &DocContext, path_str: &str) -> Option<Def> {
         .resolve_macro_to_def_inner(mark, &path, MacroKind::Bang, false);
     if let Ok(def) = res {
         if let SyntaxExtension::DeclMacro { .. } = *resolver.get_macro(def) {
-            Some(def)
-        } else {
-            None
+            return Some(def);
         }
-    } else if let Some(def) = resolver.all_macros.get(&Symbol::intern(path_str)) {
-        Some(*def)
-    } else {
-        None
     }
+    if let Some(def) = resolver.all_macros.get(&Symbol::intern(path_str)) {
+        return Some(*def);
+    }
+    None
 }
 
 #[derive(Debug)]
diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index 76f38646308..0025f21da22 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -317,7 +317,7 @@ macro_rules! assert_approx_eq {
 /// macro, but are documented here. Their implementations can be found hardcoded
 /// into libsyntax itself.
 #[cfg(dox)]
-pub mod builtin {
+mod builtin {
 
     /// Unconditionally causes compilation to fail with the given error message when encountered.
     ///
@@ -355,7 +355,7 @@ pub mod builtin {
     ///
     /// [`panic!`]: ../std/macro.panic.html
     #[stable(feature = "compile_error_macro", since = "1.20.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! compile_error {
         ($msg:expr) => ({ /* compiler built-in */ });
         ($msg:expr,) => ({ /* compiler built-in */ });
@@ -407,7 +407,7 @@ pub mod builtin {
     /// assert_eq!(s, format!("hello {}", "world"));
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! format_args {
         ($fmt:expr) => ({ /* compiler built-in */ });
         ($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ });
@@ -445,7 +445,7 @@ pub mod builtin {
     /// error: what's that?!
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! env {
         ($name:expr) => ({ /* compiler built-in */ });
         ($name:expr,) => ({ /* compiler built-in */ });
@@ -471,7 +471,7 @@ pub mod builtin {
     /// println!("the secret key might be: {:?}", key);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! option_env {
         ($name:expr) => ({ /* compiler built-in */ });
         ($name:expr,) => ({ /* compiler built-in */ });
@@ -502,7 +502,7 @@ pub mod builtin {
     /// # }
     /// ```
     #[unstable(feature = "concat_idents_macro", issue = "29599")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! concat_idents {
         ($($e:ident),+) => ({ /* compiler built-in */ });
         ($($e:ident,)+) => ({ /* compiler built-in */ });
@@ -524,7 +524,7 @@ pub mod builtin {
     /// assert_eq!(s, "test10btrue");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! concat {
         ($($e:expr),*) => ({ /* compiler built-in */ });
         ($($e:expr,)*) => ({ /* compiler built-in */ });
@@ -552,7 +552,7 @@ pub mod builtin {
     /// println!("defined on line: {}", current_line);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! line { () => ({ /* compiler built-in */ }) }
 
     /// A macro which expands to the column number on which it was invoked.
@@ -577,7 +577,7 @@ pub mod builtin {
     /// println!("defined on column: {}", current_col);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! column { () => ({ /* compiler built-in */ }) }
 
     /// A macro which expands to the file name from which it was invoked.
@@ -601,7 +601,7 @@ pub mod builtin {
     /// println!("defined in file: {}", this_file);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! file { () => ({ /* compiler built-in */ }) }
 
     /// A macro which stringifies its arguments.
@@ -620,7 +620,7 @@ pub mod builtin {
     /// assert_eq!(one_plus_one, "1 + 1");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! stringify { ($($t:tt)*) => ({ /* compiler built-in */ }) }
 
     /// Includes a utf8-encoded file as a string.
@@ -654,7 +654,7 @@ pub mod builtin {
     ///
     /// Compiling 'main.rs' and running the resulting binary will print "adiós".
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! include_str {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -691,7 +691,7 @@ pub mod builtin {
     ///
     /// Compiling 'main.rs' and running the resulting binary will print "adiós".
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! include_bytes {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -715,7 +715,7 @@ pub mod builtin {
     /// test::foo();
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! module_path { () => ({ /* compiler built-in */ }) }
 
     /// Boolean evaluation of configuration flags, at compile-time.
@@ -737,7 +737,7 @@ pub mod builtin {
     /// };
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! cfg { ($($cfg:tt)*) => ({ /* compiler built-in */ }) }
 
     /// Parse a file as an expression or an item according to the context.
@@ -780,7 +780,7 @@ pub mod builtin {
     /// Compiling 'main.rs' and running the resulting binary will print
     /// "🙈🙊🙉🙈🙊🙉".
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! include {
         ($file:expr) => ({ /* compiler built-in */ });
         ($file:expr,) => ({ /* compiler built-in */ });
@@ -833,7 +833,7 @@ pub mod builtin {
     /// assert!(a + b == 30, "a = {}, b = {}", a, b);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    #[macro_export]
+    #[rustc_doc_only_macro]
     macro_rules! assert {
         ($cond:expr) => ({ /* compiler built-in */ });
         ($cond:expr,) => ({ /* compiler built-in */ });
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 143d0d4df71..30137439e77 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -687,7 +687,8 @@ pub fn deprecated_attributes() -> Vec<&'static (&'static str, AttributeType, Att
 }
 
 pub fn is_builtin_attr(attr: &ast::Attribute) -> bool {
-    BUILTIN_ATTRIBUTES.iter().any(|&(builtin_name, _, _)| attr.check_name(builtin_name))
+    BUILTIN_ATTRIBUTES.iter().any(|&(builtin_name, _, _)| attr.check_name(builtin_name)) ||
+    attr.name().as_str().starts_with("rustc_")
 }
 
 // Attributes that have a special meaning to rustc or rustdoc