Support custom attributes when macro modularization is enabled

3 files changed, 27 insertions, 54 deletions

diff --git a/src/libsyntax/ext/base.rs b/src/libsyntax/ext/base.rs
index 1bc5cb93c11..de391ee4219 100644
--- a/src/libsyntax/ext/base.rs
+++ b/src/libsyntax/ext/base.rs
@@ -589,7 +589,7 @@ impl MacroKind {
 /// An enum representing the different kinds of syntax extensions.
 pub enum SyntaxExtension {
     /// A trivial "extension" that does nothing, only keeps the attribute and marks it as known.
-    NonMacroAttr,
+    NonMacroAttr { mark_used: bool },
 
     /// A syntax extension that is attached to an item and creates new items
     /// based upon it.
@@ -670,7 +670,7 @@ impl SyntaxExtension {
             SyntaxExtension::IdentTT(..) |
             SyntaxExtension::ProcMacro { .. } =>
                 MacroKind::Bang,
-            SyntaxExtension::NonMacroAttr |
+            SyntaxExtension::NonMacroAttr { .. } |
             SyntaxExtension::MultiDecorator(..) |
             SyntaxExtension::MultiModifier(..) |
             SyntaxExtension::AttrProcMacro(..) =>
@@ -700,7 +700,7 @@ impl SyntaxExtension {
             SyntaxExtension::AttrProcMacro(.., edition) |
             SyntaxExtension::ProcMacroDerive(.., edition) => edition,
             // Unstable legacy stuff
-            SyntaxExtension::NonMacroAttr |
+            SyntaxExtension::NonMacroAttr { .. } |
             SyntaxExtension::IdentTT(..) |
             SyntaxExtension::MultiDecorator(..) |
             SyntaxExtension::MultiModifier(..) |
@@ -739,6 +739,12 @@ pub enum Determinacy {
     Undetermined,
 }
 
+impl Determinacy {
+    pub fn determined(determined: bool) -> Determinacy {
+        if determined { Determinacy::Determined } else { Determinacy::Undetermined }
+    }
+}
+
 pub struct DummyResolver;
 
 impl Resolver for DummyResolver {
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 7148f3c00f2..72e0abfea8b 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -244,12 +244,12 @@ impl Invocation {
         }
     }
 
-    pub fn path_span(&self) -> Span {
+    pub fn path(&self) -> Option<&Path> {
         match self.kind {
-            InvocationKind::Bang { ref mac, .. } => mac.node.path.span,
-            InvocationKind::Attr { attr: Some(ref attr), .. } => attr.path.span,
-            InvocationKind::Attr { attr: None, .. } => DUMMY_SP,
-            InvocationKind::Derive { ref path, .. } => path.span,
+            InvocationKind::Bang { ref mac, .. } => Some(&mac.node.path),
+            InvocationKind::Attr { attr: Some(ref attr), .. } => Some(&attr.path),
+            InvocationKind::Attr { attr: None, .. } => None,
+            InvocationKind::Derive { ref path, .. } => Some(path),
         }
     }
 }
@@ -548,7 +548,9 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             _ => unreachable!(),
         };
 
-        attr::mark_used(&attr);
+        if let NonMacroAttr { mark_used: false } = *ext {} else {
+            attr::mark_used(&attr);
+        }
         invoc.expansion_data.mark.set_expn_info(ExpnInfo {
             call_site: attr.span,
             def_site: None,
@@ -560,7 +562,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         });
 
         match *ext {
-            NonMacroAttr => {
+            NonMacroAttr { .. } => {
                 attr::mark_known(&attr);
                 let item = item.map_attrs(|mut attrs| { attrs.push(attr); attrs });
                 Some(invoc.fragment_kind.expect_from_annotatables(iter::once(item)))
@@ -810,7 +812,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
             }
 
             MultiDecorator(..) | MultiModifier(..) |
-            AttrProcMacro(..) | SyntaxExtension::NonMacroAttr => {
+            AttrProcMacro(..) | SyntaxExtension::NonMacroAttr { .. } => {
                 self.cx.span_err(path.span,
                                  &format!("`{}` can only be used in attributes", path));
                 self.cx.trace_macros_diag();
@@ -1487,7 +1489,8 @@ impl<'a, 'b> Folder for InvocationCollector<'a, 'b> {
         };
 
         if attr.is_some() || !traits.is_empty()  {
-            if !self.cx.ecfg.macros_in_extern_enabled() {
+            if !self.cx.ecfg.macros_in_extern_enabled() &&
+               !self.cx.ecfg.custom_attribute_enabled() {
                 if let Some(ref attr) = attr {
                     emit_feature_err(&self.cx.parse_sess, "macros_in_extern", attr.span,
                                      GateIssue::Language, explain);
@@ -1668,6 +1671,7 @@ impl<'feat> ExpansionConfig<'feat> {
         fn enable_custom_derive = custom_derive,
         fn enable_format_args_nl = format_args_nl,
         fn macros_in_extern_enabled = macros_in_extern,
+        fn custom_attribute_enabled = custom_attribute,
         fn proc_macro_mod = proc_macro_mod,
         fn proc_macro_gen = proc_macro_gen,
         fn proc_macro_expr = proc_macro_expr,
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index 193e560893f..3f4ee834256 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -32,7 +32,7 @@ use attr;
 use codemap::Spanned;
 use edition::{ALL_EDITIONS, Edition};
 use syntax_pos::{Span, DUMMY_SP};
-use errors::{DiagnosticBuilder, Handler, FatalError};
+use errors::{DiagnosticBuilder, Handler};
 use visit::{self, FnKind, Visitor};
 use parse::ParseSess;
 use symbol::{keywords, Symbol};
@@ -83,8 +83,10 @@ macro_rules! declare_features {
             }
 
             pub fn use_extern_macros(&self) -> bool {
-                // The `decl_macro` and `tool_attributes` features imply `use_extern_macros`.
-                self.use_extern_macros || self.decl_macro || self.tool_attributes
+                // The `decl_macro`, `tool_attributes` and `custom_attributes`
+                // features imply `use_extern_macros`.
+                self.use_extern_macros || self.decl_macro ||
+                self.tool_attributes || self.custom_attribute
             }
         }
     };
@@ -1898,9 +1900,6 @@ pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],
     }
 
     let mut features = Features::new();
-
-    let mut feature_checker = FeatureChecker::default();
-
     let mut edition_enabled_features = FxHashMap();
 
     for &(name, .., f_edition, set) in ACTIVE_FEATURES.iter() {
@@ -1989,45 +1988,9 @@ pub fn get_features(span_handler: &Handler, krate_attrs: &[ast::Attribute],
         }
     }
 
-    feature_checker.check(span_handler);
-
     features
 }
 
-/// A collector for mutually exclusive and interdependent features and their flag spans.
-#[derive(Default)]
-struct FeatureChecker {
-    use_extern_macros: Option<Span>,
-    custom_attribute: Option<Span>,
-}
-
-impl FeatureChecker {
-    // If this method turns out to be a hotspot due to branching,
-    // the branching can be eliminated by modifying `set!()` to set these spans
-    // only for the features that need to be checked for mutual exclusion.
-    fn collect(&mut self, features: &Features, span: Span) {
-        if features.use_extern_macros() {
-            // If self.use_extern_macros is None, set to Some(span)
-            self.use_extern_macros = self.use_extern_macros.or(Some(span));
-        }
-
-        if features.custom_attribute {
-            self.custom_attribute = self.custom_attribute.or(Some(span));
-        }
-    }
-
-    fn check(self, handler: &Handler) {
-        if let (Some(pm_span), Some(ca_span)) = (self.use_extern_macros, self.custom_attribute) {
-            handler.struct_span_err(pm_span, "Cannot use `#![feature(use_extern_macros)]` and \
-                                              `#![feature(custom_attribute)] at the same time")
-                .span_note(ca_span, "`#![feature(custom_attribute)]` declared here")
-                .emit();
-
-            FatalError.raise();
-        }
-    }
-}
-
 pub fn check_crate(krate: &ast::Crate,
                    sess: &ParseSess,
                    features: &Features,