Auto merge of rust-lang#49982 - petrochenkov:noreex, r=alexcrichton

Remove unstable `macro_reexport`

It's subsumed by `feature(use_extern_macros)` and `pub use`

cc rust-lang#35896
closes rust-lang#29638
closes rust-lang#38951

Author: bors

src/librustc_resolve/build_reduced_graph.rs

@@ -71,7 +71,6 @@ impl<'a> ToNameBinding<'a> for (Def, ty::Visibility, Span, Mark) {
 struct LegacyMacroImports {
     import_all: Option<Span>,
     imports: Vec<(Name, Span)>,
-    reexports: Vec<(Name, Span)>,
 }
 
 impl<'a> Resolver<'a> {
@@ -621,7 +620,7 @@ impl<'a> Resolver<'a> {
         let legacy_imports = self.legacy_macro_imports(&item.attrs);
         let mut used = legacy_imports != LegacyMacroImports::default();
 
-        // `#[macro_use]` and `#[macro_reexport]` are only allowed at the crate root.
+        // `#[macro_use]` is only allowed at the crate root.
         if self.current_module.parent.is_some() && used {
             span_err!(self.session, item.span, E0468,
                       "an `extern crate` loading macros must be at the crate root");
@@ -669,17 +668,6 @@ impl<'a> Resolver<'a> {
                 }
             }
         }
-        for (name, span) in legacy_imports.reexports {
-            self.cstore.export_macros_untracked(module.def_id().unwrap().krate);
-            let ident = Ident::with_empty_ctxt(name);
-            let result = self.resolve_ident_in_module(module, ident, MacroNS, false, false, span);
-            if let Ok(binding) = result {
-                let (def, vis) = (binding.def(), binding.vis);
-                self.macro_exports.push(Export { ident, def, vis, span, is_import: true });
-            } else {
-                span_err!(self.session, span, E0470, "re-exported macro not found");
-            }
-        }
         used
     }
 
@@ -721,21 +709,6 @@ impl<'a> Resolver<'a> {
                     },
                     None => imports.import_all = Some(attr.span),
                 }
-            } else if attr.check_name("macro_reexport") {
-                let bad_macro_reexport = |this: &mut Self, span| {
-                    span_err!(this.session, span, E0467, "bad macro re-export");
-                };
-                if let Some(names) = attr.meta_item_list() {
-                    for attr in names {
-                        if let Some(word) = attr.word() {
-                            imports.reexports.push((word.ident.name, attr.span()));
-                        } else {
-                            bad_macro_reexport(self, attr.span());
-                        }
-                    }
-                } else {
-                    bad_macro_reexport(self, attr.span());
-                }
             }
         }
         imports

src/librustc_resolve/diagnostics.rs

@@ -1395,35 +1395,6 @@ If you would like to import all exported macros, write `macro_use` with no
 arguments.
 "##,
 
-E0467: r##"
-Macro re-export declarations were empty or malformed.
-
-Erroneous code examples:
-
-```compile_fail,E0467
-#[macro_reexport]                    // error: no macros listed for export
-extern crate core as macros_for_good;
-
-#[macro_reexport(fun_macro = "foo")] // error: not a macro identifier
-extern crate core as other_macros_for_good;
-```
-
-This is a syntax error at the level of attribute declarations.
-
-Currently, `macro_reexport` requires at least one macro name to be listed.
-Unlike `macro_use`, listing no names does not re-export all macros from the
-given crate.
-
-Decide which macros you would like to export and list them properly.
-
-These are proper re-export declarations:
-
-```ignore (cannot-doctest-multicrate-project)
-#[macro_reexport(some_macro, another_macro)]
-extern crate macros_for_good;
-```
-"##,
-
 E0468: r##"
 A non-root module attempts to import macros from another crate.
 
@@ -1496,48 +1467,6 @@ extern crate some_crate; //ok!
 ```
 "##,
 
-E0470: r##"
-A macro listed for re-export was not found.
-
-Erroneous code example:
-
-```compile_fail,E0470
-#[macro_reexport(drink, be_merry)]
-extern crate alloc;
-
-fn main() {
-    // ...
-}
-```
-
-Either the listed macro is not contained in the imported crate, or it is not
-exported from the given crate.
-
-This could be caused by a typo. Did you misspell the macro's name?
-
-Double-check the names of the macros listed for re-export, and that the crate
-in question exports them.
-
-A working version:
-
-```ignore (cannot-doctest-multicrate-project)
-// In some_crate crate:
-#[macro_export]
-macro_rules! eat {
-    ...
-}
-
-#[macro_export]
-macro_rules! drink {
-    ...
-}
-
-// In your_crate:
-#[macro_reexport(eat, drink)]
-extern crate some_crate;
-```
-"##,
-
 E0530: r##"
 A binding shadowed something it shouldn't.
 
@@ -1715,6 +1644,8 @@ register_diagnostics! {
 //  E0421, merged into 531
     E0531, // unresolved pattern path kind `name`
 //  E0427, merged into 530
+//  E0467, removed
+//  E0470, removed
     E0573,
     E0574,
     E0575,

src/librustdoc/visit_ast.rs

@@ -49,7 +49,6 @@ pub struct RustdocVisitor<'a, 'tcx: 'a, 'rcx: 'a> {
     inlining: bool,
     /// Is the current module and all of its parents public?
     inside_public_path: bool,
-    reexported_macros: FxHashSet<DefId>,
     exact_paths: Option<FxHashMap<DefId, Vec<String>>>,
 }
 
@@ -66,7 +65,6 @@ impl<'a, 'tcx, 'rcx> RustdocVisitor<'a, 'tcx, 'rcx> {
             view_item_stack: stack,
             inlining: false,
             inside_public_path: true,
-            reexported_macros: FxHashSet(),
             exact_paths: Some(FxHashMap()),
             cstore,
         }
@@ -221,7 +219,7 @@ impl<'a, 'tcx, 'rcx> RustdocVisitor<'a, 'tcx, 'rcx> {
         if let Some(exports) = self.cx.tcx.module_exports(def_id) {
             for export in exports.iter().filter(|e| e.vis == Visibility::Public) {
                 if let Def::Macro(def_id, ..) = export.def {
-                    if def_id.krate == LOCAL_CRATE || self.reexported_macros.contains(&def_id) {
+                    if def_id.krate == LOCAL_CRATE {
                         continue // These are `krate.exported_macros`, handled in `self.visit()`.
                     }
 
@@ -298,17 +296,6 @@ impl<'a, 'tcx, 'rcx> RustdocVisitor<'a, 'tcx, 'rcx> {
         let is_no_inline = use_attrs.lists("doc").has_word("no_inline") ||
                            use_attrs.lists("doc").has_word("hidden");
 
-        // Memoize the non-inlined `pub use`'d macros so we don't push an extra
-        // declaration in `visit_mod_contents()`
-        if !def_did.is_local() {
-            if let Def::Macro(did, _) = def {
-                if please_inline { return true }
-                debug!("memoizing non-inlined macro export: {:?}", def);
-                self.reexported_macros.insert(did);
-                return false;
-            }
-        }
-
         // For cross-crate impl inlining we need to know whether items are
         // reachable in documentation - a previously nonreachable item can be
         // made reachable by cross-crate inlining which we're checking here.

src/libstd/lib.rs

@@ -273,7 +273,6 @@
 #![feature(libc)]
 #![feature(link_args)]
 #![feature(linkage)]
-#![feature(macro_reexport)]
 #![feature(macro_vis_matcher)]
 #![feature(needs_panic_runtime)]
 #![feature(never_type)]
@@ -313,6 +312,7 @@
 #![feature(unboxed_closures)]
 #![feature(untagged_unions)]
 #![feature(unwind_attributes)]
+#![feature(use_extern_macros)]
 #![feature(vec_push_all)]
 #![feature(doc_cfg)]
 #![feature(doc_masked)]
@@ -347,15 +347,14 @@ use prelude::v1::*;
 #[cfg(test)] extern crate test;
 #[cfg(test)] extern crate rand;
 
-// We want to re-export a few macros from core but libcore has already been
-// imported by the compiler (via our #[no_std] attribute) In this case we just
-// add a new crate name so we can attach the re-exports to it.
-#[macro_reexport(assert_eq, assert_ne, debug_assert, debug_assert_eq,
-                 debug_assert_ne, unreachable, unimplemented, write, writeln, try)]
-extern crate core as __core;
+// 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, try};
 
+#[allow(unused_imports)] // macros from `alloc` are not used on all platforms
 #[macro_use]
-#[macro_reexport(vec, format)]
 extern crate alloc as alloc_crate;
 extern crate alloc_system;
 #[doc(masked)]
@@ -450,6 +449,8 @@ pub use alloc_crate::borrow;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::fmt;
 #[stable(feature = "rust1", since = "1.0.0")]
+pub use alloc_crate::format;
+#[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::slice;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use alloc_crate::str;