resolve/expand: Move macro stability checking to an earlier point

Author: petrochenkov

src/librustc_resolve/macros.rs

@@ -229,16 +229,27 @@ impl<'a> base::Resolver for Resolver<'a> {
             Err(determinacy) => return Err(determinacy),
         };
 
+        let span = invoc.span();
         let format = match kind {
             MacroKind::Derive => format!("derive({})", fast_print_path(path)),
             _ => fast_print_path(path),
         };
-        invoc.expansion_data.mark.set_expn_info(ext.expn_info(invoc.span(), &format));
+        invoc.expansion_data.mark.set_expn_info(ext.expn_info(span, &format));
 
         if let Res::Def(_, def_id) = res {
             if after_derive {
-                self.session.span_err(invoc.span(),
-                                      "macro attributes must be placed before `#[derive]`");
+                self.session.span_err(span, "macro attributes must be placed before `#[derive]`");
+            }
+            if let Some((feature, issue)) = ext.unstable_feature {
+                // Do not stability-check macros in the same crate.
+                let features = self.session.features_untracked();
+                if !def_id.is_local() &&
+                   !span.allows_unstable(feature) &&
+                   features.declared_lib_features.iter().all(|(feat, _)| *feat != feature) {
+                    let msg = format!("macro {}! is unstable", path);
+                    emit_feature_err(&self.session.parse_sess, feature, span,
+                                     GateIssue::Library(Some(issue)), &msg);
+                }
             }
             self.macro_defs.insert(invoc.expansion_data.mark, def_id);
             let normal_module_def_id =

src/libsyntax/ext/base.rs

@@ -738,7 +738,6 @@ pub struct ExpansionData {
     pub depth: usize,
     pub module: Rc<ModuleData>,
     pub directory_ownership: DirectoryOwnership,
-    pub crate_span: Option<Span>,
 }
 
 /// One of these is made during expansion and incrementally updated as we go;
@@ -768,7 +767,6 @@ impl<'a> ExtCtxt<'a> {
                 depth: 0,
                 module: Rc::new(ModuleData { mod_path: Vec::new(), directory: PathBuf::new() }),
                 directory_ownership: DirectoryOwnership::Owned { relative: None },
-                crate_span: None,
             },
             expansions: FxHashMap::default(),
         }

src/libsyntax/ext/expand.rs

@@ -243,7 +243,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         module.directory.pop();
         self.cx.root_path = module.directory.clone();
         self.cx.current_expansion.module = Rc::new(module);
-        self.cx.current_expansion.crate_span = Some(krate.span);
 
         let orig_mod_span = krate.module.inner;
 
@@ -668,39 +667,17 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         };
         let path = &mac.node.path;
 
-        let validate = |this: &mut Self| {
-            // feature-gate the macro invocation
-            if let Some((feature, issue)) = ext.unstable_feature {
-                let crate_span = this.cx.current_expansion.crate_span.unwrap();
-                // don't stability-check macros in the same crate
-                if !crate_span.contains(ext.span)
-                    && !span.allows_unstable(feature)
-                    && this.cx.ecfg.features.map_or(true, |feats| {
-                    // macro features will count as lib features
-                    !feats.declared_lib_features.iter().any(|&(feat, _)| feat == feature)
-                }) {
-                    let explain = format!("macro {}! is unstable", path);
-                    emit_feature_err(this.cx.parse_sess, feature, span,
-                                     GateIssue::Library(Some(issue)), &explain);
-                    this.cx.trace_macros_diag();
-                }
-            }
-
-            Ok(())
-        };
-
         let opt_expanded = match &ext.kind {
+            SyntaxExtensionKind::Bang(expander) => {
+                self.gate_proc_macro_expansion_kind(span, kind);
+                let tok_result = expander.expand(self.cx, span, mac.node.stream());
+                let result = self.parse_ast_fragment(tok_result, kind, path, span);
+                self.gate_proc_macro_expansion(span, &result);
+                result
+            }
             SyntaxExtensionKind::LegacyBang(expander) => {
-                if let Err(dummy_span) = validate(self) {
-                    dummy_span
-                } else {
-                    kind.make_from(expander.expand(
-                        self.cx,
-                        span,
-                        mac.node.stream(),
-                        Some(ext.span),
-                    ))
-                }
+                let tok_result = expander.expand(self.cx, span, mac.node.stream(), Some(ext.span));
+                kind.make_from(tok_result)
             }
 
             SyntaxExtensionKind::Attr(..) |
@@ -717,14 +694,6 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 self.cx.trace_macros_diag();
                 kind.dummy(span)
             }
-
-            SyntaxExtensionKind::Bang(expander) => {
-                self.gate_proc_macro_expansion_kind(span, kind);
-                let tok_result = expander.expand(self.cx, span, mac.node.stream());
-                let result = self.parse_ast_fragment(tok_result, kind, path, span);
-                self.gate_proc_macro_expansion(span, &result);
-                result
-            }
         };
 
         if opt_expanded.is_some() {