resolve: Some macro resolution refactoring

src/librustc_resolve/lib.rs

@@ -80,7 +80,7 @@ use std::mem::replace;
 use rustc_data_structures::sync::Lrc;
 
 use resolve_imports::{ImportDirective, ImportDirectiveSubclass, NameResolution, ImportResolver};
-use macros::{InvocationData, LegacyBinding, MacroBinding};
+use macros::{InvocationData, LegacyBinding};
 
 // NB: This module needs to be declared first so diagnostics are
 // registered before they are used.
@@ -1399,7 +1399,7 @@ pub struct Resolver<'a, 'b: 'a> {
     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)>,
-
+    /// macro-expanded `macro_rules` shadowing existing macros
     disallowed_shadowing: Vec<&'a LegacyBinding<'a>>,
 
     arenas: &'a ResolverArenas<'a>,
@@ -3529,7 +3529,7 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
             } else if opt_ns == Some(MacroNS) {
                 assert!(ns == TypeNS);
                 self.resolve_lexical_macro_path_segment(ident, ns, record_used, record_used,
-                                                        false, path_span).map(MacroBinding::binding)
+                                                        false, path_span).map(|(b, _)| b)
             } else {
                 let record_used_id =
                     if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None };
@@ -4431,6 +4431,42 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         vis.is_accessible_from(module.normal_ancestor_id, self)
     }
 
+    fn report_ambiguity_error(
+        &self, name: Name, span: Span, _lexical: bool,
+        def1: Def, is_import1: bool, is_glob1: bool, from_expansion1: bool, span1: Span,
+        def2: Def, is_import2: bool, _is_glob2: bool, _from_expansion2: bool, span2: Span,
+    ) {
+        let participle = |is_import: bool| if is_import { "imported" } else { "defined" };
+        let msg1 = format!("`{}` could refer to the name {} here", name, participle(is_import1));
+        let msg2 =
+            format!("`{}` could also refer to the name {} here", name, participle(is_import2));
+        let note = if from_expansion1 {
+            Some(if let Def::Macro(..) = def1 {
+                format!("macro-expanded {} do not shadow",
+                        if is_import1 { "macro imports" } else { "macros" })
+            } else {
+                format!("macro-expanded {} do not shadow when used in a macro invocation path",
+                        if is_import1 { "imports" } else { "items" })
+            })
+        } else if is_glob1 {
+            Some(format!("consider adding an explicit import of `{}` to disambiguate", name))
+        } else {
+            None
+        };
+
+        let mut err = struct_span_err!(self.session, span, E0659, "`{}` is ambiguous", name);
+        err.span_note(span1, &msg1);
+        match def2 {
+            Def::Macro(..) if span2.is_dummy() =>
+                err.note(&format!("`{}` is also a builtin macro", name)),
+            _ => err.span_note(span2, &msg2),
+        };
+        if let Some(note) = note {
+            err.note(&note);
+        }
+        err.emit();
+    }
+
     fn report_errors(&mut self, krate: &Crate) {
         self.report_shadowing_errors();
         self.report_with_use_injections(krate);
@@ -4446,30 +4482,15 @@ impl<'a, 'crateloader: 'a> Resolver<'a, 'crateloader> {
         }
 
         for &AmbiguityError { span, name, b1, b2, lexical } in &self.ambiguity_errors {
-            if !reported_spans.insert(span) { continue }
-            let participle = |binding: &NameBinding| {
-                if binding.is_import() { "imported" } else { "defined" }
-            };
-            let msg1 = format!("`{}` could refer to the name {} here", name, participle(b1));
-            let msg2 = format!("`{}` could also refer to the name {} here", name, participle(b2));
-            let note = if b1.expansion == Mark::root() || !lexical && b1.is_glob_import() {
-                format!("consider adding an explicit import of `{}` to disambiguate", name)
-            } else if let Def::Macro(..) = b1.def() {
-                format!("macro-expanded {} do not shadow",
-                        if b1.is_import() { "macro imports" } else { "macros" })
-            } else {
-                format!("macro-expanded {} do not shadow when used in a macro invocation path",
-                        if b1.is_import() { "imports" } else { "items" })
-            };
-
-            let mut err = struct_span_err!(self.session, span, E0659, "`{}` is ambiguous", name);
-            err.span_note(b1.span, &msg1);
-            match b2.def() {
-                Def::Macro(..) if b2.span.is_dummy() =>
-                    err.note(&format!("`{}` is also a builtin macro", name)),
-                _ => err.span_note(b2.span, &msg2),
-            };
-            err.note(&note).emit();
+            if reported_spans.insert(span) {
+                self.report_ambiguity_error(
+                    name, span, lexical,
+                    b1.def(), b1.is_import(), b1.is_glob_import(),
+                    b1.expansion != Mark::root(), b1.span,
+                    b2.def(), b2.is_import(), b2.is_glob_import(),
+                    b2.expansion != Mark::root(), b2.span,
+                );
+            }
         }
 
         for &PrivacyError(span, name, binding) in &self.privacy_errors {