resolve: Support resolving identifier macros without their own ID

Invocation/expansion ID (aka `Mark`) is not really necessary for resolving a macro path.
What is really necessary is its parent module, parent expansion and parent legacy scope.
This is required for validation resolutions of built-in attributes, which don't get their own `Mark`s

Author: petrochenkov

src/librustc_resolve/lib.rs

@@ -81,7 +81,7 @@ use std::mem::replace;
 use rustc_data_structures::sync::Lrc;
 
 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
-use macros::{InvocationData, LegacyBinding};
+use macros::{InvocationData, LegacyBinding, LegacyScope};
 
 // NB: This module needs to be declared first so diagnostics are
 // registered before they are used.
@@ -1010,7 +1010,7 @@ pub struct ModuleData<'a> {
     normal_ancestor_id: DefId,
 
     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
-    legacy_macro_resolutions: RefCell<Vec<(Mark, Ident, MacroKind, Option<Def>)>>,
+    legacy_macro_resolutions: RefCell<Vec<(Ident, MacroKind, Mark, LegacyScope<'a>, Option<Def>)>>,
     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
 
     // Macro invocations that can expand into items in this module.
@@ -1276,19 +1276,18 @@ impl<'a> NameBinding<'a> {
         if self.is_extern_crate() { "extern crate" } else { self.def().kind_name() }
     }
 
-    // Suppose that we resolved macro invocation with `invoc_id` to binding `binding` at some
-    // expansion round `max(invoc_id, binding)` when they both emerged from macros.
+    // Suppose that we resolved macro invocation with `invoc_parent_expansion` to binding `binding`
+    // at some expansion round `max(invoc, binding)` when they both emerged from macros.
     // Then this function returns `true` if `self` may emerge from a macro *after* that
     // in some later round and screw up our previously found resolution.
     // See more detailed explanation in
     // https://github.com/rust-lang/rust/pull/53778#issuecomment-419224049
-    fn may_appear_after(&self, invoc_id: Mark, binding: &NameBinding) -> bool {
-        // self > max(invoc_id, binding) => !(self <= invoc_id || self <= binding)
+    fn may_appear_after(&self, invoc_parent_expansion: Mark, binding: &NameBinding) -> bool {
+        // self > max(invoc, binding) => !(self <= invoc || self <= binding)
         // Expansions are partially ordered, so "may appear after" is an inversion of
         // "certainly appears before or simultaneously" and includes unordered cases.
         let self_parent_expansion = self.expansion;
         let other_parent_expansion = binding.expansion;
-        let invoc_parent_expansion = invoc_id.parent();
         let certainly_before_other_or_simultaneously =
             other_parent_expansion.is_descendant_of(self_parent_expansion);
         let certainly_before_invoc_or_simultaneously =
@@ -3493,16 +3492,16 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         path_span: Span,
         crate_lint: CrateLint,
     ) -> PathResult<'a> {
-        self.resolve_path_with_invoc_id(base_module, path, opt_ns, Mark::root(),
-                                        record_used, path_span, crate_lint)
+        self.resolve_path_with_parent_expansion(base_module, path, opt_ns, Mark::root(),
+                                                record_used, path_span, crate_lint)
     }
 
-    fn resolve_path_with_invoc_id(
+    fn resolve_path_with_parent_expansion(
         &mut self,
         base_module: Option<ModuleOrUniformRoot<'a>>,
         path: &[Ident],
         opt_ns: Option<Namespace>, // `None` indicates a module path
-        invoc_id: Mark,
+        parent_expansion: Mark,
         record_used: bool,
         path_span: Span,
         crate_lint: CrateLint,
@@ -3595,7 +3594,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
                 self.resolve_ident_in_module(module, ident, ns, record_used, path_span)
             } else if opt_ns == Some(MacroNS) {
                 assert!(ns == TypeNS);
-                self.resolve_lexical_macro_path_segment(ident, ns, invoc_id, record_used,
+                self.resolve_lexical_macro_path_segment(ident, ns, parent_expansion, record_used,
                                                         record_used, false, path_span)
                                                         .map(|(binding, _)| binding)
             } else {

src/librustc_resolve/macros.rs

@@ -313,7 +313,7 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
         None
     }
 
-    fn resolve_macro_invocation(&mut self, invoc: &Invocation, scope: Mark, force: bool)
+    fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: Mark, force: bool)
                                 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
         let (path, kind, derives_in_scope) = match invoc.kind {
             InvocationKind::Attr { attr: None, .. } =>
@@ -326,7 +326,7 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
                 (path, MacroKind::Derive, &[][..]),
         };
 
-        let (def, ext) = self.resolve_macro_to_def(path, kind, scope, derives_in_scope, force)?;
+        let (def, ext) = self.resolve_macro_to_def(path, kind, invoc_id, derives_in_scope, force)?;
 
         if let Def::Macro(def_id, _) = def {
             self.macro_defs.insert(invoc.expansion_data.mark, def_id);
@@ -341,10 +341,10 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
         Ok(Some(ext))
     }
 
-    fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, scope: Mark,
+    fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
                           derives_in_scope: &[ast::Path], force: bool)
                           -> Result<Lrc<SyntaxExtension>, Determinacy> {
-        Ok(self.resolve_macro_to_def(path, kind, scope, derives_in_scope, force)?.1)
+        Ok(self.resolve_macro_to_def(path, kind, invoc_id, derives_in_scope, force)?.1)
     }
 
     fn check_unused_macros(&self) {
@@ -366,10 +366,10 @@ impl<'a, 'crateloader: 'a> base::Resolver for Resolver<'a, 'crateloader> {
 }
 
 impl<'a, 'cl> Resolver<'a, 'cl> {
-    fn resolve_macro_to_def(&mut self, path: &ast::Path, kind: MacroKind, scope: Mark,
+    fn resolve_macro_to_def(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
                             derives_in_scope: &[ast::Path], force: bool)
                             -> Result<(Def, Lrc<SyntaxExtension>), Determinacy> {
-        let def = self.resolve_macro_to_def_inner(path, kind, scope, derives_in_scope, force);
+        let def = self.resolve_macro_to_def_inner(path, kind, invoc_id, derives_in_scope, force);
 
         // Report errors and enforce feature gates for the resolved macro.
         if def != Err(Determinacy::Undetermined) {
@@ -439,8 +439,9 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         let ast::Path { ref segments, span } = *path;
         let mut path: Vec<_> = segments.iter().map(|seg| seg.ident).collect();
         let invocation = self.invocations[&invoc_id];
-        let module = invocation.module.get();
-        self.current_module = if module.is_trait() { module.parent.unwrap() } else { module };
+        let parent_expansion = invoc_id.parent();
+        let parent_legacy_scope = invocation.parent_legacy_scope.get();
+        self.current_module = invocation.module.get().nearest_item_scope();
 
         // Possibly apply the macro helper hack
         if kind == MacroKind::Bang && path.len() == 1 &&
@@ -450,8 +451,9 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         }
 
         if path.len() > 1 {
-            let def = match self.resolve_path_with_invoc_id(None, &path, Some(MacroNS), invoc_id,
-                                                            false, span, CrateLint::No) {
+            let def = match self.resolve_path_with_parent_expansion(None, &path, Some(MacroNS),
+                                                                    parent_expansion, false, span,
+                                                                    CrateLint::No) {
                 PathResult::NonModule(path_res) => match path_res.base_def() {
                     Def::Err => Err(Determinacy::Determined),
                     def @ _ => {
@@ -471,19 +473,19 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                     Err(Determinacy::Determined)
                 },
             };
-            self.current_module.nearest_item_scope().macro_resolutions.borrow_mut()
+            self.current_module.macro_resolutions.borrow_mut()
                 .push((path.into_boxed_slice(), span));
             return def;
         }
 
         let legacy_resolution = self.resolve_legacy_scope(
-            path[0], invoc_id, invocation.parent_legacy_scope.get(), false, kind == MacroKind::Attr
+            path[0], parent_expansion, parent_legacy_scope, false, kind == MacroKind::Attr
         );
         let result = if let Some(legacy_binding) = legacy_resolution {
             Ok(legacy_binding.def())
         } else {
-            match self.resolve_lexical_macro_path_segment(path[0], MacroNS, invoc_id, false, force,
-                                                          kind == MacroKind::Attr, span) {
+            match self.resolve_lexical_macro_path_segment(path[0], MacroNS, parent_expansion, false,
+                                                          force, kind == MacroKind::Attr, span) {
                 Ok((binding, _)) => Ok(binding.def_ignoring_ambiguity()),
                 Err(Determinacy::Undetermined) => return Err(Determinacy::Undetermined),
                 Err(Determinacy::Determined) => {
@@ -493,8 +495,8 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             }
         };
 
-        self.current_module.nearest_item_scope().legacy_macro_resolutions.borrow_mut()
-            .push((invoc_id, path[0], kind, result.ok()));
+        self.current_module.legacy_macro_resolutions.borrow_mut()
+            .push((path[0], kind, parent_expansion, parent_legacy_scope, result.ok()));
 
         if let Ok(Def::NonMacroAttr(NonMacroAttrKind::Custom)) = result {} else {
             return result;
@@ -541,7 +543,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         &mut self,
         mut ident: Ident,
         ns: Namespace,
-        invoc_id: Mark,
+        parent_expansion: Mark,
         record_used: bool,
         force: bool,
         is_attr: bool,
@@ -754,7 +756,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                         // Found another solution, if the first one was "weak", report an error.
                         if result.0.def() != innermost_result.0.def() &&
                            (innermost_result.0.is_glob_import() ||
-                            innermost_result.0.may_appear_after(invoc_id, result.0)) {
+                            innermost_result.0.may_appear_after(parent_expansion, result.0)) {
                             self.ambiguity_errors.push(AmbiguityError {
                                 ident,
                                 b1: innermost_result.0,
@@ -798,8 +800,8 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
 
     fn resolve_legacy_scope(&mut self,
                             ident: Ident,
-                            invoc_id: Mark,
-                            invoc_parent_legacy_scope: LegacyScope<'a>,
+                            parent_expansion: Mark,
+                            parent_legacy_scope: LegacyScope<'a>,
                             record_used: bool,
                             is_attr: bool)
                             -> Option<&'a NameBinding<'a>> {
@@ -826,7 +828,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
         let mut innermost_result: Option<&NameBinding> = None;
 
         // Go through all the scopes and try to resolve the name.
-        let mut where_to_resolve = invoc_parent_legacy_scope;
+        let mut where_to_resolve = parent_legacy_scope;
         loop {
             let result = match where_to_resolve {
                 LegacyScope::Binding(legacy_binding) if ident == legacy_binding.ident =>
@@ -854,7 +856,7 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                     if let Some(innermost_result) = innermost_result {
                         // Found another solution, if the first one was "weak", report an error.
                         if result.def() != innermost_result.def() &&
-                           innermost_result.may_appear_after(invoc_id, result) {
+                           innermost_result.may_appear_after(parent_expansion, result) {
                             self.ambiguity_errors.push(AmbiguityError {
                                 ident,
                                 b1: innermost_result,
@@ -891,14 +893,14 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
             }
         }
 
-        for &(invoc_id, ident, kind, def) in module.legacy_macro_resolutions.borrow().iter() {
+        for &(ident, kind, parent_expansion, parent_legacy_scope, def)
+                in module.legacy_macro_resolutions.borrow().iter() {
             let span = ident.span;
-            let invocation = self.invocations[&invoc_id];
             let legacy_resolution = self.resolve_legacy_scope(
-                ident, invoc_id, invocation.parent_legacy_scope.get(), true, kind == MacroKind::Attr
+                ident, parent_expansion, parent_legacy_scope, true, kind == MacroKind::Attr
             );
             let resolution = self.resolve_lexical_macro_path_segment(
-                ident, MacroNS, invoc_id, true, true, kind == MacroKind::Attr, span
+                ident, MacroNS, parent_expansion, true, true, kind == MacroKind::Attr, span
             );
 
             let check_consistency = |this: &Self, new_def: Def| {
@@ -932,12 +934,13 @@ impl<'a, 'cl> Resolver<'a, 'cl> {
                     err.emit();
                 },
                 (Some(legacy_binding), Ok((binding, FromPrelude(from_prelude))))
-                        if !from_prelude || legacy_binding.may_appear_after(invoc_id, binding) => {
-                    if legacy_binding.def_ignoring_ambiguity() != binding.def_ignoring_ambiguity() {
-                        self.report_ambiguity_error(ident, legacy_binding, binding);
-                    }
+                        if legacy_binding.def() != binding.def_ignoring_ambiguity() &&
+                           (!from_prelude ||
+                            legacy_binding.may_appear_after(parent_expansion, binding)) => {
+                    self.report_ambiguity_error(ident, legacy_binding, binding);
                 },
                 // OK, non-macro-expanded legacy wins over prelude even if defs are different
+                // Also, legacy and modern can co-exist if their defs are same
                 (Some(legacy_binding), Ok(_)) |
                 // OK, unambiguous resolution
                 (Some(legacy_binding), Err(_)) => {

src/libsyntax/ext/base.rs

@@ -727,10 +727,9 @@ pub trait Resolver {
     fn find_legacy_attr_invoc(&mut self, attrs: &mut Vec<Attribute>, allow_derive: bool)
                               -> Option<Attribute>;
 
-    fn resolve_macro_invocation(&mut self, invoc: &Invocation, scope: Mark, force: bool)
+    fn resolve_macro_invocation(&mut self, invoc: &Invocation, invoc_id: Mark, force: bool)
                                 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy>;
-
-    fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, scope: Mark,
+    fn resolve_macro_path(&mut self, path: &ast::Path, kind: MacroKind, invoc_id: Mark,
                           derives_in_scope: &[ast::Path], force: bool)
                           -> Result<Lrc<SyntaxExtension>, Determinacy>;
 
@@ -764,11 +763,11 @@ impl Resolver for DummyResolver {
     fn resolve_imports(&mut self) {}
     fn find_legacy_attr_invoc(&mut self, _attrs: &mut Vec<Attribute>, _allow_derive: bool)
                               -> Option<Attribute> { None }
-    fn resolve_macro_invocation(&mut self, _invoc: &Invocation, _scope: Mark, _force: bool)
+    fn resolve_macro_invocation(&mut self, _invoc: &Invocation, _invoc_id: Mark, _force: bool)
                                 -> Result<Option<Lrc<SyntaxExtension>>, Determinacy> {
         Err(Determinacy::Determined)
     }
-    fn resolve_macro_path(&mut self, _path: &ast::Path, _kind: MacroKind, _scope: Mark,
+    fn resolve_macro_path(&mut self, _path: &ast::Path, _kind: MacroKind, _invoc_id: Mark,
                           _derives_in_scope: &[ast::Path], _force: bool)
                           -> Result<Lrc<SyntaxExtension>, Determinacy> {
         Err(Determinacy::Determined)