Silence confusing 'unused import' warnings.

Author: m-ou-se

compiler/rustc_resolve/src/diagnostics.rs

@@ -986,6 +986,9 @@ impl<'a> Resolver<'a> {
                             import.span,
                             &format!("`{}` is imported here, but {}", ident, it_is),
                         );
+                        // Silence the 'unused import' warning we might get,
+                        // since this diagnostic already covers that import.
+                        self.record_use(ident, binding, false);
                         return;
                     }
                 }

src/test/ui/macros/issue-88206.rs

@@ -1,11 +1,9 @@
 // compile-flags: -Z deduplicate-diagnostics=yes
 
 #![warn(unused_imports)]
-//~^ NOTE lint level
 
 use std::str::*;
-//~^ WARNING unused import
-//~| NOTE `from_utf8` is imported here, but it is not a macro
+//~^ NOTE `from_utf8` is imported here, but it is not a macro
 //~| NOTE `from_utf8_mut` is imported here, but it is not a derive macro
 //~| NOTE `from_utf8_unchecked` is imported here, but it is not an attribute
 
@@ -15,8 +13,7 @@ mod hey {
 }
 
 use hey::{Serialize, Deserialize};
-//~^ WARNING unused import
-//~| NOTE `Serialize` is imported here, but it is not a derive macro
+//~^ NOTE `Serialize` is imported here, but it is not a derive macro
 //~| NOTE `Deserialize` is imported here, but it is not an attribute
 
 #[derive(Serialize)]

src/test/ui/macros/issue-88206.stderr

@@ -1,120 +1,102 @@
 error: cannot find macro `test` in this scope
-  --> $DIR/issue-88206.rs:60:5
+  --> $DIR/issue-88206.rs:57:5
    |
 LL |     test!();
    |     ^^^^
    |
    = note: `test` is in scope, but it is an attribute
 
 error: cannot find macro `Copy` in this scope
-  --> $DIR/issue-88206.rs:56:5
+  --> $DIR/issue-88206.rs:53:5
    |
 LL |     Copy!();
    |     ^^^^
    |
    = note: `Copy` is in scope, but it is a derive macro
 
 error: cannot find macro `Box` in this scope
-  --> $DIR/issue-88206.rs:52:5
+  --> $DIR/issue-88206.rs:49:5
    |
 LL |     Box!();
    |     ^^^
    |
    = note: `Box` is in scope, but it is not a macro
 
 error: cannot find macro `from_utf8` in this scope
-  --> $DIR/issue-88206.rs:49:5
+  --> $DIR/issue-88206.rs:46:5
    |
 LL |     from_utf8!();
    |     ^^^^^^^^^
    |
 note: `from_utf8` is imported here, but it is not a macro
-  --> $DIR/issue-88206.rs:6:5
+  --> $DIR/issue-88206.rs:5:5
    |
 LL | use std::str::*;
    |     ^^^^^^^^^^^
 
 error: cannot find attribute `println` in this scope
-  --> $DIR/issue-88206.rs:43:3
+  --> $DIR/issue-88206.rs:40:3
    |
 LL | #[println]
    |   ^^^^^^^
    |
    = note: `println` is in scope, but it is a function-like macro
 
 error: cannot find attribute `from_utf8_unchecked` in this scope
-  --> $DIR/issue-88206.rs:39:3
+  --> $DIR/issue-88206.rs:36:3
    |
 LL | #[from_utf8_unchecked]
    |   ^^^^^^^^^^^^^^^^^^^
    |
 note: `from_utf8_unchecked` is imported here, but it is not an attribute
-  --> $DIR/issue-88206.rs:6:5
+  --> $DIR/issue-88206.rs:5:5
    |
 LL | use std::str::*;
    |     ^^^^^^^^^^^
 
 error: cannot find attribute `Deserialize` in this scope
-  --> $DIR/issue-88206.rs:35:3
+  --> $DIR/issue-88206.rs:32:3
    |
 LL | #[Deserialize]
    |   ^^^^^^^^^^^
    |
 note: `Deserialize` is imported here, but it is not an attribute
-  --> $DIR/issue-88206.rs:17:22
+  --> $DIR/issue-88206.rs:15:22
    |
 LL | use hey::{Serialize, Deserialize};
    |                      ^^^^^^^^^^^
 
 error: cannot find derive macro `println` in this scope
-  --> $DIR/issue-88206.rs:30:10
+  --> $DIR/issue-88206.rs:27:10
    |
 LL | #[derive(println)]
    |          ^^^^^^^
    |
    = note: `println` is in scope, but it is a function-like macro
 
 error: cannot find derive macro `from_utf8_mut` in this scope
-  --> $DIR/issue-88206.rs:26:10
+  --> $DIR/issue-88206.rs:23:10
    |
 LL | #[derive(from_utf8_mut)]
    |          ^^^^^^^^^^^^^
    |
 note: `from_utf8_mut` is imported here, but it is not a derive macro
-  --> $DIR/issue-88206.rs:6:5
+  --> $DIR/issue-88206.rs:5:5
    |
 LL | use std::str::*;
    |     ^^^^^^^^^^^
 
 error: cannot find derive macro `Serialize` in this scope
-  --> $DIR/issue-88206.rs:22:10
+  --> $DIR/issue-88206.rs:19:10
    |
 LL | #[derive(Serialize)]
    |          ^^^^^^^^^
    |
 note: `Serialize` is imported here, but it is not a derive macro
-  --> $DIR/issue-88206.rs:17:11
+  --> $DIR/issue-88206.rs:15:11
    |
 LL | use hey::{Serialize, Deserialize};
    |           ^^^^^^^^^
 
-warning: unused import: `std::str::*`
-  --> $DIR/issue-88206.rs:6:5
-   |
-LL | use std::str::*;
-   |     ^^^^^^^^^^^
-   |
-note: the lint level is defined here
-  --> $DIR/issue-88206.rs:3:9
-   |
-LL | #![warn(unused_imports)]
-   |         ^^^^^^^^^^^^^^
-
-warning: unused imports: `Deserialize`, `Serialize`
-  --> $DIR/issue-88206.rs:17:11
-   |
-LL | use hey::{Serialize, Deserialize};
-   |           ^^^^^^^^^  ^^^^^^^^^^^
-
-error: aborting due to 10 previous errors; 2 warnings emitted
+error: aborting due to 10 previous errors