Prohibit using macro-expanded macro_export macros through module-re…

…lative paths

src/librustc_resolve/build_reduced_graph.rs

@@ -789,7 +789,6 @@ impl<'a, 'b, 'cl> BuildReducedGraphVisitor<'a, 'b, 'cl> {
  fn visit_invoc(&mut self, id: ast::NodeId) -> &'b InvocationData<'b> {
  let mark = id.placeholder_to_mark();
  self.resolver.current_module.unresolved_invocations.borrow_mut().insert(mark);
- self.resolver.unresolved_invocations_macro_export.insert(mark);
  let invocation = self.resolver.invocations[&mark];
  invocation.module.set(self.resolver.current_module);
  invocation.legacy_scope.set(self.legacy_scope);

src/librustc_resolve/lib.rs

@@ -1385,6 +1385,8 @@ pub struct Resolver<'a, 'b: 'a> {
  use_injections: Vec<UseError<'a>>,
  /// `use` injections for proc macros wrongly imported with #[macro_use]
  proc_mac_errors: Vec<macros::ProcMacError>,
+ /// crate-local macro expanded `macro_export` referred to by a module-relative path
+ macro_expanded_macro_export_errors: BTreeSet<(Span, Span)>,
 
  gated_errors: FxHashSet<Span>,
  disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
@@ -1432,9 +1434,6 @@ pub struct Resolver<'a, 'b: 'a> {
 
  /// Only supposed to be used by rustdoc, otherwise should be false.
  pub ignore_extern_prelude_feature: bool,
-
- /// Macro invocations in the whole crate that can expand into a `#[macro_export] macro_rules`.
- unresolved_invocations_macro_export: FxHashSet<Mark>,
 }
 
 /// Nothing really interesting here, it just provides memory for the rest of the crate.
@@ -1706,6 +1705,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
  proc_mac_errors: Vec::new(),
  gated_errors: FxHashSet(),
  disallowed_shadowing: Vec::new(),
+ macro_expanded_macro_export_errors: BTreeSet::new(),
 
  arenas,
  dummy_binding: arenas.alloc_name_binding(NameBinding {
@@ -1737,7 +1737,6 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
  current_type_ascription: Vec::new(),
  injected_crate: None,
  ignore_extern_prelude_feature: false,
- unresolved_invocations_macro_export: FxHashSet(),
  }
  }
 
@@ -4126,6 +4125,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
  ns: Namespace,
  module: Module<'a>,
  found_traits: &mut Vec<TraitCandidate>) {
+ assert!(ns == TypeNS || ns == ValueNS);
  let mut traits = module.traits.borrow_mut();
  if traits.is_none() {
  let mut collected_traits = Vec::new();
@@ -4371,6 +4371,14 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
  self.report_proc_macro_import(krate);
  let mut reported_spans = FxHashSet();
 
+ for &(span_use, span_def) in &self.macro_expanded_macro_export_errors {
+ let msg = "macro-expanded `macro_export` macros from the current crate \
+ cannot be referred to by absolute paths";
+ self.session.struct_span_err(span_use, msg)
+ .span_note(span_def, "the macro is defined here")
+ .emit();
+ }
+
  for &AmbiguityError { span, name, b1, b2, lexical } in &self.ambiguity_errors {
  if !reported_spans.insert(span) { continue }
  let participle = |binding: &NameBinding| {

src/librustc_resolve/macros.rs

@@ -196,9 +196,7 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
 
  self.current_module = invocation.module.get();
  self.current_module.unresolved_invocations.borrow_mut().remove(&mark);
- self.unresolved_invocations_macro_export.remove(&mark);
  self.current_module.unresolved_invocations.borrow_mut().extend(derives);
- self.unresolved_invocations_macro_export.extend(derives);
  for &derive in derives {
  self.invocations.insert(derive, invocation);
  }

src/librustc_resolve/resolve_imports.rs

@@ -146,6 +146,14 @@ impl<'a, 'crateloader> Resolver<'a, 'crateloader> {
  .try_borrow_mut()
  .map_err(|_| Determined)?; // This happens when there is a cycle of imports
 
+ if let Some(binding) = resolution.binding {
+ if !restricted_shadowing && binding.expansion != Mark::root() {
+ if let NameBindingKind::Def(_, true) = binding.kind {
+ self.macro_expanded_macro_export_errors.insert((path_span, binding.span));
+ }
+ }
+ }
+
  if record_used {
  if let Some(binding) = resolution.binding {
  if let Some(shadowed_glob) = resolution.shadowed_glob {
@@ -211,9 +219,15 @@ impl<'a, 'crateloader> Resolver<'a, 'crateloader> {
  // if it cannot be shadowed by some new item/import expanded from a macro.
  // This happens either if there are no unexpanded macros, or expanded names cannot
  // shadow globs (that happens in macro namespace or with restricted shadowing).
- let unexpanded_macros = !module.unresolved_invocations.borrow().is_empty() ||
- (ns == MacroNS && ptr::eq(module, self.graph_root) &&
- !self.unresolved_invocations_macro_export.is_empty());
+ //
+ // Additionally, any macro in any module can plant names in the root module if it creates
+ // `macro_export` macros, so the root module effectively has unresolved invocations if any
+ // module has unresolved invocations.
+ // However, it causes resolution/expansion to stuck too often (#53144), so, to make
+ // progress, we have to ignore those potential unresolved invocations from other modules
+ // and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
+ // shadowing is enabled, see `macro_expanded_macro_export_errors`).
+ let unexpanded_macros = !module.unresolved_invocations.borrow().is_empty();
  if let Some(binding) = resolution.binding {
  if !unexpanded_macros || ns == MacroNS || restricted_shadowing {
  return check_usable(self, binding);

src/test/compile-fail-fulldeps/proc-macro/proc-macro-attributes.rs

@@ -21,7 +21,7 @@ extern crate derive_b;
 #[C] //~ ERROR: The attribute `C` is currently unknown to the compiler
 #[B(D)]
 #[B(E = "foo")]
-#[B arbitrary tokens] //~ expected one of `(` or `=`, found `arbitrary`
+#[B arbitrary tokens] //~ ERROR arbitrary tokens in non-macro attributes are unstable
 struct B;
 
 fn main() {}

src/test/ui/imports/local-modularized-tricky-fail-3.rs

@@ -0,0 +1,32 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Crate-local macro expanded `macro_export` macros cannot be accessed with module-relative paths.
+
+#![feature(use_extern_macros)]
+
+macro_rules! define_exported { () => {
+ #[macro_export]
+ macro_rules! exported {
+ () => ()
+ }
+}}
+
+define_exported!();
+
+mod m {
+ use exported;
+ //~^ ERROR macro-expanded `macro_export` macros from the current crate cannot
+}
+
+fn main() {
+ ::exported!();
+ //~^ ERROR macro-expanded `macro_export` macros from the current crate cannot
+}

src/test/ui/imports/local-modularized-tricky-fail-3.stderr

@@ -0,0 +1,36 @@
+error: macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths
+ --> $DIR/local-modularized-tricky-fail-3.rs:25:9
+ |
+LL | use exported;
+ | ^^^^^^^^
+ |
+note: the macro is defined here
+ --> $DIR/local-modularized-tricky-fail-3.rs:17:5
+ |
+LL | / macro_rules! exported {
+LL | | () => ()
+LL | | }
+ | |_____^
+...
+LL | define_exported!();
+ | ------------------- in this macro invocation
+
+error: macro-expanded `macro_export` macros from the current crate cannot be referred to by absolute paths
+ --> $DIR/local-modularized-tricky-fail-3.rs:30:5
+ |
+LL | ::exported!();
+ | ^^^^^^^^^^
+ |
+note: the macro is defined here
+ --> $DIR/local-modularized-tricky-fail-3.rs:17:5
+ |
+LL | / macro_rules! exported {
+LL | | () => ()
+LL | | }
+ | |_____^
+...
+LL | define_exported!();
+ | ------------------- in this macro invocation
+
+error: aborting due to 2 previous errors
+