Make no_implicit_prelude not suppress tool attributes

compiler/rustc_resolve/src/ident.rs

@@ -161,7 +161,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                 Scope::ExternPreludeItems | Scope::ExternPreludeFlags => {
                     use_prelude || module_and_extern_prelude || extern_prelude
                 }
-                Scope::ToolAttributePrelude => use_prelude,
+                Scope::ToolAttributePrelude => true,
                 Scope::StdLibPrelude => use_prelude || ns == MacroNS,
                 Scope::BuiltinTypes => true,
             };

tests/ui/tool-attributes/no_implicit_prelude.rs

@@ -17,8 +17,8 @@ mod test2 {
         pub use ::std::derive as format_args;
     }
 
-    #[rustfmt::skip]
-    //~^ ERROR cannot find module or crate `rustfmt` in this scope
+    #[my_tool::attr] // Unaffected by the `no_implicit_prelude` attribute
+    #[rustfmt::skip] // Unaffected by the `no_implicit_prelude` attribute
     #[clippy::format_args(Debug)]
     //~^ ERROR attribute macro `clippy::format_args` is ambiguous
     struct Foo;

tests/ui/tool-attributes/no_implicit_prelude.stderr

@@ -16,12 +16,5 @@ LL |     #[clippy::format_args(Debug)]
    = note: ambiguous because of a name conflict with a tool namespace
    = note: `clippy` could refer to a tool namespace
 
-error[E0433]: cannot find module or crate `rustfmt` in this scope
-  --> $DIR/no_implicit_prelude.rs:20:7
-   |
-LL |     #[rustfmt::skip]
-   |       ^^^^^^^ use of unresolved module or unlinked crate `rustfmt`
-
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0433`.