Add new ambiguity error for tools

compiler/rustc_resolve/src/ident.rs

@@ -109,7 +109,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             ScopeSet::All(ns)
             | ScopeSet::Module(ns, _)
             | ScopeSet::ModuleAndExternPrelude(ns, _) => (ns, None),
-            ScopeSet::ExternPrelude => (TypeNS, None),
+            ScopeSet::AttrParent | ScopeSet::ExternPrelude => (TypeNS, None),
             ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind)),
         };
         let module = match scope_set {
@@ -124,6 +124,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let mut scope = match ns {
             _ if module_only || module_and_extern_prelude => Scope::ModuleNonGlobs(module, None),
             _ if extern_prelude => Scope::ExternPreludeItems,
+            _ if matches!(scope_set, ScopeSet::AttrParent) => Scope::ToolPrelude,
             TypeNS | ValueNS => Scope::ModuleNonGlobs(module, None),
             MacroNS => Scope::DeriveHelpers(parent_scope.expansion),
         };
@@ -156,7 +157,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 Scope::ExternPreludeItems | Scope::ExternPreludeFlags => {
                     use_prelude || module_and_extern_prelude || extern_prelude
                 }
-                Scope::ToolPrelude => use_prelude,
+                Scope::ToolPrelude => true,
                 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
                 Scope::BuiltinTypes => true,
             };
@@ -222,8 +223,8 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 Scope::BuiltinAttrs => break, // nowhere else to search
                 Scope::ExternPreludeItems => Scope::ExternPreludeFlags,
                 Scope::ExternPreludeFlags if module_and_extern_prelude || extern_prelude => break,
-                Scope::ExternPreludeFlags => Scope::ToolPrelude,
-                Scope::ToolPrelude => Scope::StdLibPrelude,
+                Scope::ExternPreludeFlags => Scope::StdLibPrelude,
+                Scope::ToolPrelude => Scope::ModuleNonGlobs(module, None),
                 Scope::StdLibPrelude => match ns {
                     TypeNS => Scope::BuiltinTypes,
                     ValueNS => break, // nowhere else to search
@@ -424,7 +425,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             ScopeSet::All(ns)
             | ScopeSet::Module(ns, _)
             | ScopeSet::ModuleAndExternPrelude(ns, _) => (ns, None),
-            ScopeSet::ExternPrelude => (TypeNS, None),
+            ScopeSet::AttrParent | ScopeSet::ExternPrelude => (TypeNS, None),
             ScopeSet::Macro(macro_kind) => (MacroNS, Some(macro_kind)),
         };
         let derive_fallback_lint_id = match finalize {
@@ -720,7 +721,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     None => Err(Determinacy::Determined),
                 }
             }
-            Scope::ToolPrelude => match self.registered_tool_decls.get(&ident) {
+            Scope::ToolPrelude => match self.registered_tool_decls.get(&ident.name) {
                 Some(decl) => Ok(*decl),
                 None => Err(Determinacy::Determined),
             },
@@ -839,6 +840,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
 
         let ambiguity_error_kind = if is_builtin(innermost_res) || is_builtin(res) {
             Some(AmbiguityKind::BuiltinAttr)
+        } else if matches!(innermost_scope, Scope::ToolPrelude)
+            || matches!(scope, Scope::ToolPrelude)
+        {
+            Some(AmbiguityKind::ToolAttr)
         } else if innermost_res == derive_helper_compat {
             Some(AmbiguityKind::DeriveHelper)
         } else if res == derive_helper_compat && innermost_res != derive_helper {
@@ -1947,7 +1952,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             } else {
                 self.reborrow().resolve_ident_in_scope_set(
                     ident,
-                    ScopeSet::All(ns),
+                    if opt_ns == Some(MacroNS) && !is_last {
+                        // Resolving parent scope for MacroNS (where all attributes belong to, even
+                        // for tool or built-in macros).
+                        ScopeSet::AttrParent
+                    } else {
+                        ScopeSet::All(ns)
+                    },
                     parent_scope,
                     finalize,
                     ignore_decl,

compiler/rustc_resolve/src/lib.rs

@@ -145,7 +145,11 @@ enum Scope<'ra> {
 #[derive(Clone, Copy, Debug)]
 enum ScopeSet<'ra> {
     /// All scopes with the given namespace.
+    ///
+    /// Registered attribute tools are not included; they're available with `AttrParent` only.
     All(Namespace),
+    /// Scopes when resolving for parent scopes for attributes. This is `All` plus registered attribute tools.
+    AttrParent,
     /// Two scopes inside a module, for non-glob and glob bindings.
     Module(Namespace, Module<'ra>),
     /// A module, then extern prelude (used for mixed 2015-2018 mode in macros).
@@ -1082,6 +1086,7 @@ struct DelayedVisResolutionError<'ra> {
 #[derive(Clone, Copy, PartialEq, Debug)]
 enum AmbiguityKind {
     BuiltinAttr,
+    ToolAttr,
     DeriveHelper,
     MacroRulesVsModularized,
     GlobVsOuter,
@@ -1094,6 +1099,7 @@ impl AmbiguityKind {
     fn descr(self) -> &'static str {
         match self {
             AmbiguityKind::BuiltinAttr => "a name conflict with a builtin attribute",
+            AmbiguityKind::ToolAttr => "a name conflict with a tool attribute",
             AmbiguityKind::DeriveHelper => "a name conflict with a derive helper attribute",
             AmbiguityKind::MacroRulesVsModularized => {
                 "a conflict between a `macro_rules` name and a non-`macro_rules` name from another module"
@@ -1423,7 +1429,7 @@ pub struct Resolver<'ra, 'tcx> {
     dummy_decl: Decl<'ra>,
     builtin_type_decls: FxHashMap<Symbol, Decl<'ra>>,
     builtin_attr_decls: FxHashMap<Symbol, Decl<'ra>>,
-    registered_tool_decls: FxHashMap<IdentKey, Decl<'ra>>,
+    registered_tool_decls: FxHashMap<Symbol, Decl<'ra>>,
     macro_names: FxHashSet<IdentKey> = default::fx_hash_set(),
     builtin_macros: FxHashMap<Symbol, SyntaxExtensionKind> = default::fx_hash_map(),
     registered_tools: &'tcx RegisteredTools,
@@ -1845,7 +1851,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 .map(|&ident| {
                     let res = Res::ToolMod;
                     let decl = arenas.new_pub_def_decl(res, ident.span, LocalExpnId::ROOT);
-                    (IdentKey::new(ident), decl)
+                    (ident.name, decl)
                 })
                 .collect(),
             registered_tools,

tests/ui/diagnostic_namespace/existing_proc_macros.rs

@@ -1,4 +1,3 @@
-//@ check-pass
 //@ proc-macro: proc-macro-helper.rs
 
 extern crate proc_macro_helper;
@@ -16,7 +15,7 @@ mod test2 {
         pub use proc_macro_helper::diagnostic as on_unimplemented;
     }
 
-    #[diagnostic::on_unimplemented]
+    #[diagnostic::on_unimplemented(message = "")] //~ ERROR: ambiguous
     trait Foo {}
 }
 

tests/ui/diagnostic_namespace/existing_proc_macros.stderr

@@ -0,0 +1,20 @@
+error[E0659]: `diagnostic` is ambiguous
+  --> $DIR/existing_proc_macros.rs:18:7
+   |
+LL |     #[diagnostic::on_unimplemented(message = "")]
+   |       ^^^^^^^^^^ ambiguous name
+   |
+   = note: ambiguous because of a name conflict with a tool attribute
+   = note: `diagnostic` could refer to a tool module
+note: `diagnostic` could also refer to the module defined here
+  --> $DIR/existing_proc_macros.rs:14:5
+   |
+LL | /     mod diagnostic {
+LL | |         pub use proc_macro_helper::diagnostic as on_unimplemented;
+LL | |     }
+   | |_____^
+   = help: use `self::diagnostic` to refer to this module unambiguously
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0659`.

tests/ui/resolve/prelude-order.rs

@@ -13,10 +13,10 @@
 Type:
 | ...... |  tool  | extern | macro  | lang   | libs |
 |   tool |    N/A |                   mirror
-| extern | extern |    N/A |             universe
+| extern |      † |    N/A |             universe
 |  macro |    N/A |    N/A |    N/A |
-|   lang |   tool | extern |    N/A |   N/A  |
-|   libs |   tool | extern |    N/A |   X    |  N/A |
+|   lang |      † | extern |    N/A |   N/A  |
+|   libs |      † | extern |    N/A |   X    |  N/A |
 
 Macro:
 | ...... |  tool  | extern | macro  | lang   | libs |
@@ -28,7 +28,7 @@ Macro:
 
 Value: N/A. Only libs has items in the value namespace.
 
-† ambiguous
+† ambiguous if used as attributes
 X don't care (controlled namespace with no overlap)
 
 * Types are tested with `#[name::inner]`. Macros are tested with `#[name]`.
@@ -59,15 +59,15 @@ extern crate macro_helpers as _;
 /* lang and libs implicitly in scope */
 
 // tool/extern -> extern
-#[type_ns::inner] //~ ERROR cannot find `inner` in `type_ns`
+#[type_ns::inner] //~ ERROR ambiguous
 fn t1() {}
 
 // tool/lang -> tool
-#[i8::inner] // ok
+#[i8::inner] //~ ERROR ambiguous
 fn t2() {}
 
 // tool/libs -> tool
-#[Sync::not_real] // ok
+#[Sync::not_real] //~ ERROR ambiguous
 fn t3() {}
 
 // extern/lang -> extern

tests/ui/resolve/prelude-order.stderr

@@ -1,9 +1,3 @@
-error[E0433]: cannot find `inner` in `type_ns`
-  --> $DIR/prelude-order.rs:62:12
-   |
-LL | #[type_ns::inner]
-   |            ^^^^^ could not find `inner` in `type_ns`
-
 error[E0433]: cannot find `inner` in `usize`
   --> $DIR/prelude-order.rs:74:10
    |
@@ -21,6 +15,54 @@ help: consider importing this enum instead
 LL + use std::option::Option;
    |
 
+error[E0659]: `type_ns` is ambiguous
+  --> $DIR/prelude-order.rs:62:3
+   |
+LL | #[type_ns::inner]
+   |   ^^^^^^^ ambiguous name
+   |
+   = note: ambiguous because of a name conflict with a tool attribute
+note: `type_ns` could refer to the tool module defined here
+  --> $DIR/prelude-order.rs:46:18
+   |
+LL | #![register_tool(type_ns)] // extern prelude. type.
+   |                  ^^^^^^^
+note: `type_ns` could also refer to the crate imported here
+  --> $DIR/prelude-order.rs:51:1
+   |
+LL | extern crate macro_helpers as type_ns; // tool prelude. type.
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   = help: use `crate::type_ns` to refer to this crate unambiguously
+
+error[E0659]: `i8` is ambiguous
+  --> $DIR/prelude-order.rs:66:3
+   |
+LL | #[i8::inner]
+   |   ^^ ambiguous name
+   |
+   = note: ambiguous because of a name conflict with a tool attribute
+   = note: `i8` could refer to a builtin type
+note: `i8` could also refer to the tool module defined here
+  --> $DIR/prelude-order.rs:47:18
+   |
+LL | #![register_tool(i8)]      // lang   prelude. type.
+   |                  ^^
+
+error[E0659]: `Sync` is ambiguous
+  --> $DIR/prelude-order.rs:70:3
+   |
+LL | #[Sync::not_real]
+   |   ^^^^ ambiguous name
+   |
+   = note: ambiguous because of a name conflict with a tool attribute
+note: `Sync` could refer to the tool module defined here
+  --> $DIR/prelude-order.rs:48:18
+   |
+LL | #![register_tool(Sync)]    // libs   prelude. type.
+   |                  ^^^^
+note: `Sync` could also refer to a trait from prelude
+  --> $SRC_DIR/std/src/prelude/mod.rs:LL:COL
+
 error[E0308]: mismatched types
   --> $DIR/prelude-order.rs:83:1
    |
@@ -41,7 +83,7 @@ LL | #[global_allocator]
    |
    = note: this error originates in the attribute macro `global_allocator` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 5 previous errors
+error: aborting due to 7 previous errors
 
-Some errors have detailed explanations: E0308, E0433, E0573.
+Some errors have detailed explanations: E0308, E0433, E0573, E0659.
 For more information about an error, try `rustc --explain E0308`.

tests/ui/resolve/tool-import.rs

@@ -1,8 +1,7 @@
 //@ edition: 2018
 
 use clippy::time::Instant;
-//~^ ERROR: cannot find module `clippy`
-//~| NOTE: `clippy` is a tool module
+//~^ ERROR: cannot find module or crate `clippy`
 
 fn main() {
     Instant::now();

tests/ui/resolve/tool-import.stderr

@@ -1,8 +1,10 @@
-error[E0433]: cannot find module `clippy` in this scope
+error[E0433]: cannot find module or crate `clippy` in this scope
   --> $DIR/tool-import.rs:3:5
    |
 LL | use clippy::time::Instant;
-   |     ^^^^^^ `clippy` is a tool module, not a module
+   |     ^^^^^^ use of unresolved module or unlinked crate `clippy`
+   |
+   = help: you might be missing a crate named `clippy`
 
 error: aborting due to 1 previous error
 

tests/ui/rust-2018/uniform-paths/auxiliary/cross-crate.rs

@@ -2,4 +2,3 @@
 
 pub use ignore as built_in_attr;
 pub use u8 as built_in_type;
-pub use rustfmt as tool_mod;

tests/ui/rust-2018/uniform-paths/cross-crate.rs

@@ -5,8 +5,6 @@ extern crate cross_crate;
 use cross_crate::*;
 
 #[built_in_attr] //~ ERROR cannot use a built-in attribute through an import
-#[tool_mod::skip] //~ ERROR cannot use a tool module through an import
-                  //~| ERROR cannot use a tool module through an import
 fn main() {
     let _: built_in_type; // OK
 }

tests/ui/rust-2018/uniform-paths/cross-crate.stderr

@@ -10,30 +10,5 @@ note: the built-in attribute imported here
 LL | use cross_crate::*;
    |     ^^^^^^^^^^^^^^
 
-error: cannot use a tool module through an import
-  --> $DIR/cross-crate.rs:8:3
-   |
-LL | #[tool_mod::skip]
-   |   ^^^^^^^^
-   |
-note: the tool module imported here
-  --> $DIR/cross-crate.rs:5:5
-   |
-LL | use cross_crate::*;
-   |     ^^^^^^^^^^^^^^
-
-error: cannot use a tool module through an import
-  --> $DIR/cross-crate.rs:8:3
-   |
-LL | #[tool_mod::skip]
-   |   ^^^^^^^^
-   |
-note: the tool module imported here
-  --> $DIR/cross-crate.rs:5:5
-   |
-LL | use cross_crate::*;
-   |     ^^^^^^^^^^^^^^
-   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-
-error: aborting due to 3 previous errors
+error: aborting due to 1 previous error
 

tests/ui/rust-2018/uniform-paths/prelude-fail-2.rs

@@ -6,16 +6,6 @@ mod builtin {
     pub use inline as imported_inline;
 }
 
-// Tool module
-use rustfmt as imported_rustfmt;
-mod tool_mod {
-    pub use rustfmt as imported_rustfmt;
-}
-
 #[imported_inline] //~ ERROR cannot use a built-in attribute through an import
 #[builtin::imported_inline] //~ ERROR cannot use a built-in attribute through an import
-#[imported_rustfmt::skip] //~ ERROR cannot use a tool module through an import
-                          //~| ERROR cannot use a tool module through an import
-#[tool_mod::imported_rustfmt::skip] //~ ERROR cannot use a tool module through an import
-                                    //~| ERROR cannot use a tool module through an import
 fn main() {}