Auto merge of #54336 - petrochenkov:preuni, r=alexcrichton

resolve: Some refactorings in preparation for uniform paths 2.0

The main result is that in-scope resolution performed during macro expansion / import resolution is now consolidated in a single function (`fn early_resolve_ident_in_lexical_scope`), which can now be used for resolving first import segments as well when uniform paths are enabled.

r? @ghost

src/Cargo.lock

@@ -2388,6 +2388,7 @@ name = "rustc_resolve"
 version = "0.0.0"
 dependencies = [
  "arena 0.0.0",
+ "bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc 0.0.0",
  "rustc_data_structures 0.0.0",

src/librustc/hir/def.rs

@@ -36,6 +36,8 @@ pub enum NonMacroAttrKind {
     Tool,
     /// Single-segment custom attribute registered by a derive macro (`#[serde(default)]`).
     DeriveHelper,
+    /// Single-segment custom attriubte registered by a legacy plugin (`register_attribute`).
+    LegacyPluginHelper,
     /// Single-segment custom attribute not registered in any way (`#[my_attr]`).
     Custom,
 }
@@ -259,6 +261,7 @@ fn descr(self) -> &'static str {
             NonMacroAttrKind::Builtin => "built-in attribute",
             NonMacroAttrKind::Tool => "tool attribute",
             NonMacroAttrKind::DeriveHelper => "derive helper attribute",
+            NonMacroAttrKind::LegacyPluginHelper => "legacy plugin helper attribute",
             NonMacroAttrKind::Custom => "custom attribute",
         }
     }

src/librustc/ich/impls_hir.rs

@@ -1012,6 +1012,7 @@ fn to_stable_hash_key(&self,
     Builtin,
     Tool,
     DeriveHelper,
+    LegacyPluginHelper,
     Custom,
 });
 

src/librustc_resolve/Cargo.toml

@@ -10,6 +10,7 @@ crate-type = ["dylib"]
 test = false
 
 [dependencies]
+bitflags = "1.0"
 log = "0.4"
 syntax = { path = "../libsyntax" }
 rustc = { path = "../librustc" }

src/librustc_resolve/lib.rs

@@ -17,6 +17,8 @@
 #![feature(rustc_diagnostic_macros)]
 #![feature(slice_sort_by_cached_key)]
 
+#[macro_use]
+extern crate bitflags;
 #[macro_use]
 extern crate log;
 #[macro_use]
@@ -1012,7 +1014,8 @@ pub struct ModuleData<'a> {
     normal_ancestor_id: DefId,
 
     resolutions: RefCell<FxHashMap<(Ident, Namespace), &'a RefCell<NameResolution<'a>>>>,
-    legacy_macro_resolutions: RefCell<Vec<(Ident, MacroKind, ParentScope<'a>, Option<Def>)>>,
+    legacy_macro_resolutions: RefCell<Vec<(Ident, MacroKind, ParentScope<'a>,
+                                           Option<&'a NameBinding<'a>>)>>,
     macro_resolutions: RefCell<Vec<(Box<[Ident]>, Span)>>,
     builtin_attrs: RefCell<Vec<(Ident, ParentScope<'a>)>>,
 
@@ -1210,10 +1213,6 @@ fn def_ignoring_ambiguity(&self) -> Def {
         }
     }
 
-    fn get_macro<'b: 'a>(&self, resolver: &mut Resolver<'a, 'b>) -> Lrc<SyntaxExtension> {
-        resolver.get_macro(self.def_ignoring_ambiguity())
-    }
-
     // We sometimes need to treat variants as `pub` for backwards compatibility
     fn pseudo_vis(&self) -> ty::Visibility {
         if self.is_variant() && self.def().def_id().is_local() {
@@ -3664,8 +3663,8 @@ fn resolve_path_with_parent_scope(
                 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, None, parent_scope, record_used,
-                                                        record_used, path_span).map(|(b, _)| b)
+                self.early_resolve_ident_in_lexical_scope(ident, ns, None, parent_scope,
+                                                          record_used, record_used, path_span)
             } else {
                 let record_used_id =
                     if record_used { crate_lint.node_id().or(Some(CRATE_NODE_ID)) } else { None };

src/librustc_resolve/resolve_imports.rs

@@ -334,7 +334,7 @@ pub fn resolve_ident_in_module_unadjusted(&mut self,
         // expansion. With restricted shadowing names from globs and macro expansions cannot
         // shadow names from outer scopes, so we can freely fallback from module search to search
         // in outer scopes. To continue search in outer scopes we have to lie a bit and return
-        // `Determined` to `resolve_lexical_macro_path_segment` even if the correct answer
+        // `Determined` to `early_resolve_ident_in_lexical_scope` even if the correct answer
         // for in-module resolution could be `Undetermined`.
         if restricted_shadowing {
             return Err(Determined);

src/libsyntax/ext/expand.rs

@@ -220,14 +220,6 @@ pub struct Invocation {
     pub expansion_data: ExpansionData,
 }
 
-// Needed for feature-gating attributes used after derives or together with test/bench
-#[derive(Clone, Copy, PartialEq)]
-pub enum TogetherWith {
-    None,
-    Derive,
-    TestBench,
-}
-
 pub enum InvocationKind {
     Bang {
         mac: ast::Mac,
@@ -238,7 +230,8 @@ pub enum InvocationKind {
         attr: Option<ast::Attribute>,
         traits: Vec<Path>,
         item: Annotatable,
-        together_with: TogetherWith,
+        // We temporarily report errors for attribute macros placed after derives
+        after_derive: bool,
     },
     Derive {
         path: Path,
@@ -1084,19 +1077,17 @@ fn collect_attr(&mut self,
                     traits: Vec<Path>,
                     item: Annotatable,
                     kind: AstFragmentKind,
-                    together_with: TogetherWith)
+                    after_derive: bool)
                     -> AstFragment {
-        self.collect(kind, InvocationKind::Attr { attr, traits, item, together_with })
+        self.collect(kind, InvocationKind::Attr { attr, traits, item, after_derive })
     }
 
-    fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, together_with: &mut TogetherWith)
+    fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, after_derive: &mut bool)
                        -> Option<ast::Attribute> {
         let attr = attrs.iter()
                         .position(|a| {
                             if a.path == "derive" {
-                                *together_with = TogetherWith::Derive
-                            } else if a.path == "rustc_test_marker2" {
-                                *together_with = TogetherWith::TestBench
+                                *after_derive = true;
                             }
                             !attr::is_known(a) && !is_builtin_attr(a)
                         })
@@ -1109,19 +1100,15 @@ fn find_attr_invoc(&self, attrs: &mut Vec<ast::Attribute>, together_with: &mut T
                                  "non-builtin inner attributes are unstable");
             }
         }
-        if together_with == &TogetherWith::None &&
-           attrs.iter().any(|a| a.path == "rustc_test_marker2") {
-            *together_with = TogetherWith::TestBench;
-        }
         attr
     }
 
     /// If `item` is an attr invocation, remove and return the macro attribute and derive traits.
     fn classify_item<T>(&mut self, mut item: T)
-                        -> (Option<ast::Attribute>, Vec<Path>, T, TogetherWith)
+                        -> (Option<ast::Attribute>, Vec<Path>, T, /* after_derive */ bool)
         where T: HasAttrs,
     {
-        let (mut attr, mut traits, mut together_with) = (None, Vec::new(), TogetherWith::None);
+        let (mut attr, mut traits, mut after_derive) = (None, Vec::new(), false);
 
         item = item.map_attrs(|mut attrs| {
             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs,
@@ -1130,20 +1117,20 @@ fn classify_item<T>(&mut self, mut item: T)
                 return attrs;
             }
 
-            attr = self.find_attr_invoc(&mut attrs, &mut together_with);
+            attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
             traits = collect_derives(&mut self.cx, &mut attrs);
             attrs
         });
 
-        (attr, traits, item, together_with)
+        (attr, traits, item, after_derive)
     }
 
     /// Alternative of `classify_item()` that ignores `#[derive]` so invocations fallthrough
     /// to the unused-attributes lint (making it an error on statements and expressions
     /// is a breaking change)
     fn classify_nonitem<T: HasAttrs>(&mut self, mut item: T)
-                                     -> (Option<ast::Attribute>, T, TogetherWith) {
-        let (mut attr, mut together_with) = (None, TogetherWith::None);
+                                     -> (Option<ast::Attribute>, T, /* after_derive */ bool) {
+        let (mut attr, mut after_derive) = (None, false);
 
         item = item.map_attrs(|mut attrs| {
             if let Some(legacy_attr_invoc) = self.cx.resolver.find_legacy_attr_invoc(&mut attrs,
@@ -1152,11 +1139,11 @@ fn classify_nonitem<T: HasAttrs>(&mut self, mut item: T)
                 return attrs;
             }
 
-            attr = self.find_attr_invoc(&mut attrs, &mut together_with);
+            attr = self.find_attr_invoc(&mut attrs, &mut after_derive);
             attrs
         });
 
-        (attr, item, together_with)
+        (attr, item, after_derive)
     }
 
     fn configure<T: HasAttrs>(&mut self, node: T) -> Option<T> {
@@ -1195,7 +1182,7 @@ fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
         expr.node = self.cfg.configure_expr_kind(expr.node);
 
         // ignore derives so they remain unused
-        let (attr, expr, together_with) = self.classify_nonitem(expr);
+        let (attr, expr, after_derive) = self.classify_nonitem(expr);
 
         if attr.is_some() {
             // collect the invoc regardless of whether or not attributes are permitted here
@@ -1204,7 +1191,7 @@ fn fold_expr(&mut self, expr: P<ast::Expr>) -> P<ast::Expr> {
 
             // AstFragmentKind::Expr requires the macro to emit an expression
             return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
-                                     AstFragmentKind::Expr, together_with).make_expr();
+                                     AstFragmentKind::Expr, after_derive).make_expr();
         }
 
         if let ast::ExprKind::Mac(mac) = expr.node {
@@ -1220,13 +1207,13 @@ fn fold_opt_expr(&mut self, expr: P<ast::Expr>) -> Option<P<ast::Expr>> {
         expr.node = self.cfg.configure_expr_kind(expr.node);
 
         // ignore derives so they remain unused
-        let (attr, expr, together_with) = self.classify_nonitem(expr);
+        let (attr, expr, after_derive) = self.classify_nonitem(expr);
 
         if attr.is_some() {
             attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
 
             return self.collect_attr(attr, vec![], Annotatable::Expr(P(expr)),
-                                     AstFragmentKind::OptExpr, together_with).make_opt_expr();
+                                     AstFragmentKind::OptExpr, after_derive).make_opt_expr();
         }
 
         if let ast::ExprKind::Mac(mac) = expr.node {
@@ -1258,18 +1245,18 @@ fn fold_pat(&mut self, pat: P<ast::Pat>) -> P<ast::Pat> {
 
         // we'll expand attributes on expressions separately
         if !stmt.is_expr() {
-            let (attr, derives, stmt_, together_with) = if stmt.is_item() {
+            let (attr, derives, stmt_, after_derive) = if stmt.is_item() {
                 self.classify_item(stmt)
             } else {
                 // ignore derives on non-item statements so it falls through
                 // to the unused-attributes lint
-                let (attr, stmt, together_with) = self.classify_nonitem(stmt);
-                (attr, vec![], stmt, together_with)
+                let (attr, stmt, after_derive) = self.classify_nonitem(stmt);
+                (attr, vec![], stmt, after_derive)
             };
 
             if attr.is_some() || !derives.is_empty() {
                 return self.collect_attr(attr, derives, Annotatable::Stmt(P(stmt_)),
-                                         AstFragmentKind::Stmts, together_with).make_stmts();
+                                         AstFragmentKind::Stmts, after_derive).make_stmts();
             }
 
             stmt = stmt_;
@@ -1311,10 +1298,10 @@ fn fold_block(&mut self, block: P<Block>) -> P<Block> {
     fn fold_item(&mut self, item: P<ast::Item>) -> SmallVec<[P<ast::Item>; 1]> {
         let item = configure!(self, item);
 
-        let (attr, traits, item, together_with) = self.classify_item(item);
+        let (attr, traits, item, after_derive) = self.classify_item(item);
         if attr.is_some() || !traits.is_empty() {
             return self.collect_attr(attr, traits, Annotatable::Item(item),
-                                     AstFragmentKind::Items, together_with).make_items();
+                                     AstFragmentKind::Items, after_derive).make_items();
         }
 
         match item.node {
@@ -1386,10 +1373,10 @@ fn fold_block(&mut self, block: P<Block>) -> P<Block> {
     fn fold_trait_item(&mut self, item: ast::TraitItem) -> SmallVec<[ast::TraitItem; 1]> {
         let item = configure!(self, item);
 
-        let (attr, traits, item, together_with) = self.classify_item(item);
+        let (attr, traits, item, after_derive) = self.classify_item(item);
         if attr.is_some() || !traits.is_empty() {
             return self.collect_attr(attr, traits, Annotatable::TraitItem(P(item)),
-                                     AstFragmentKind::TraitItems, together_with).make_trait_items()
+                                     AstFragmentKind::TraitItems, after_derive).make_trait_items()
         }
 
         match item.node {
@@ -1405,10 +1392,10 @@ fn fold_block(&mut self, block: P<Block>) -> P<Block> {
     fn fold_impl_item(&mut self, item: ast::ImplItem) -> SmallVec<[ast::ImplItem; 1]> {
         let item = configure!(self, item);
 
-        let (attr, traits, item, together_with) = self.classify_item(item);
+        let (attr, traits, item, after_derive) = self.classify_item(item);
         if attr.is_some() || !traits.is_empty() {
             return self.collect_attr(attr, traits, Annotatable::ImplItem(P(item)),
-                                     AstFragmentKind::ImplItems, together_with).make_impl_items();
+                                     AstFragmentKind::ImplItems, after_derive).make_impl_items();
         }
 
         match item.node {
@@ -1440,11 +1427,11 @@ fn fold_foreign_mod(&mut self, foreign_mod: ast::ForeignMod) -> ast::ForeignMod
     fn fold_foreign_item(&mut self, foreign_item: ast::ForeignItem)
         -> SmallVec<[ast::ForeignItem; 1]>
     {
-        let (attr, traits, foreign_item, together_with) = self.classify_item(foreign_item);
+        let (attr, traits, foreign_item, after_derive) = self.classify_item(foreign_item);
 
         if attr.is_some() || !traits.is_empty() {
             return self.collect_attr(attr, traits, Annotatable::ForeignItem(P(foreign_item)),
-                                     AstFragmentKind::ForeignItems, together_with)
+                                     AstFragmentKind::ForeignItems, after_derive)
                                      .make_foreign_items();
         }
 

src/libsyntax/feature_gate.rs

@@ -995,10 +995,6 @@ pub fn is_builtin_attr(attr: &ast::Attribute) -> bool {
                                      "the `#[rustc_test_marker]` attribute \
                                       is used internally to track tests",
                                      cfg_fn!(rustc_attrs))),
-    ("rustc_test_marker2", Normal, Gated(Stability::Unstable,
-                                         "rustc_attrs",
-                                         "temporarily used by rustc to report some errors",
-                                         cfg_fn!(rustc_attrs))),
     ("rustc_transparent_macro", Whitelisted, Gated(Stability::Unstable,
                                                    "rustc_attrs",
                                                    "used internally for testing macro hygiene",

src/libsyntax_ext/test.rs

@@ -49,7 +49,7 @@ pub fn expand_test_or_bench(
     // If we're not in test configuration, remove the annotated item
     if !cx.ecfg.should_test { return vec![]; }
 
-    let mut item =
+    let item =
         if let Annotatable::Item(i) = item { i }
         else {
             cx.parse_sess.span_diagnostic.span_fatal(item.span(),
@@ -192,12 +192,6 @@ pub fn expand_test_or_bench(
 
     debug!("Synthetic test item:\n{}\n", pprust::item_to_string(&test_const));
 
-    // Temporarily add another marker to the original item for error reporting
-    let marker2 = cx.attribute(
-        attr_sp, cx.meta_word(attr_sp, Symbol::intern("rustc_test_marker2"))
-    );
-    item.attrs.push(marker2);
-
     vec![
         // Access to libtest under a gensymed name
         Annotatable::Item(test_extern),

src/test/run-pass-fulldeps/macro-crate.rs

@@ -19,8 +19,8 @@
 #[macro_use] #[no_link]
 extern crate macro_crate_test;
 
-#[derive(PartialEq, Clone, Debug)]
 #[rustc_into_multi_foo]
+#[derive(PartialEq, Clone, Debug)]
 fn foo() -> AnotherFakeTypeThatHadBetterGoAway {}
 
 // Check that the `#[into_multi_foo]`-generated `foo2` is configured away

src/test/ui-fulldeps/attribute-order-restricted.rs

 // aux-build:attr_proc_macro.rs
-// compile-flags:--test
 
-#![feature(test)]
-
-extern crate test;
 extern crate attr_proc_macro;
 use attr_proc_macro::*;
 
@@ -15,18 +11,4 @@
 #[attr_proc_macro] //~ ERROR macro attributes must be placed before `#[derive]`
 struct After;
 
-#[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-#[test]
-fn test_before() {}
-
-#[test]
-#[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-fn test_after() {}
-
-#[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-#[bench]
-fn bench_before(b: &mut test::Bencher) {}
-
-#[bench]
-#[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-fn bench_after(b: &mut test::Bencher) {}
+fn main() {}

src/test/ui-fulldeps/attribute-order-restricted.stderr

 error: macro attributes must be placed before `#[derive]`
-  --> $DIR/attribute-order-restricted.rs:15:1
+  --> $DIR/attribute-order-restricted.rs:11:1
    |
 LL | #[attr_proc_macro] //~ ERROR macro attributes must be placed before `#[derive]`
    | ^^^^^^^^^^^^^^^^^^
 
-error: macro attributes cannot be used together with `#[test]` or `#[bench]`
-  --> $DIR/attribute-order-restricted.rs:18:1
-   |
-LL | #[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-   | ^^^^^^^^^^^^^^^^^^
-
-error: macro attributes cannot be used together with `#[test]` or `#[bench]`
-  --> $DIR/attribute-order-restricted.rs:23:1
-   |
-LL | #[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-   | ^^^^^^^^^^^^^^^^^^
-
-error: macro attributes cannot be used together with `#[test]` or `#[bench]`
-  --> $DIR/attribute-order-restricted.rs:26:1
-   |
-LL | #[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-   | ^^^^^^^^^^^^^^^^^^
-
-error: macro attributes cannot be used together with `#[test]` or `#[bench]`
-  --> $DIR/attribute-order-restricted.rs:31:1
-   |
-LL | #[attr_proc_macro] //~ ERROR macro attributes cannot be used together with `#[test]` or `#[bench]`
-   | ^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 5 previous errors
+error: aborting due to previous error
 

src/test/ui/imports/shadow_builtin_macros.stderr

-error[E0659]: `panic` is ambiguous
-  --> $DIR/shadow_builtin_macros.rs:43:5
-   |
-LL |     panic!(); //~ ERROR `panic` is ambiguous
-   |     ^^^^^ ambiguous name
-   |
-note: `panic` could refer to the name defined here
-  --> $DIR/shadow_builtin_macros.rs:40:9
-   |
-LL |         macro_rules! panic { () => {} }
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |     } }
-LL |     m!();
-   |     ----- in this macro invocation
-   = note: `panic` is also a builtin macro
-   = note: macro-expanded macros do not shadow
-
 error[E0659]: `panic` is ambiguous
   --> $DIR/shadow_builtin_macros.rs:25:14
    |
@@ -43,6 +26,23 @@ LL |     ::two_macros::m!(use foo::panic;);
    = note: `panic` is also a builtin macro
    = note: macro-expanded macro imports do not shadow
 
+error[E0659]: `panic` is ambiguous
+  --> $DIR/shadow_builtin_macros.rs:43:5
+   |
+LL |     panic!(); //~ ERROR `panic` is ambiguous
+   |     ^^^^^ ambiguous name
+   |
+note: `panic` could refer to the name defined here
+  --> $DIR/shadow_builtin_macros.rs:40:9
+   |
+LL |         macro_rules! panic { () => {} }
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     } }
+LL |     m!();
+   |     ----- in this macro invocation
+   = note: `panic` is also a builtin macro
+   = note: macro-expanded macros do not shadow
+
 error[E0659]: `n` is ambiguous
   --> $DIR/shadow_builtin_macros.rs:59:5
    |