Expand lint note

Author: Jules-Bertholet

compiler/rustc_lint/messages.ftl

@@ -949,7 +949,7 @@ lint_unused_op = unused {$op} that must be used
 lint_unused_result = unused result of type `{$ty}`
 
 lint_unused_visibilities = visibility qualifiers have no effect on `const _` declarations
-    .note = there is no declared name for the qualifier to affect
+    .note = `const _` does not declare a name, so there is nothing for the qualifier to apply to
     .suggestion = remove the qualifier
 
 lint_use_let_underscore_ignore_suggestion = use `let _ = ...` to ignore the expression or result

tests/ui/lint/unused-visibilities.stderr

@@ -4,7 +4,7 @@ warning: visibility qualifiers have no effect on `const _` declarations
 LL | pub const _: () = {};
    | ^^^ help: remove the qualifier
    |
-   = note: there is no declared name for the qualifier to affect
+   = note: `const _` does not declare a name, so there is nothing for the qualifier to apply to
 note: the lint level is defined here
   --> $DIR/unused-visibilities.rs:4:9
    |
@@ -17,7 +17,7 @@ warning: visibility qualifiers have no effect on `const _` declarations
 LL | pub(self) const _: () = {};
    | ^^^^^^^^^ help: remove the qualifier
    |
-   = note: there is no declared name for the qualifier to affect
+   = note: `const _` does not declare a name, so there is nothing for the qualifier to apply to
 
 warning: visibility qualifiers have no effect on `const _` declarations
   --> $DIR/unused-visibilities.rs:14:9
@@ -28,7 +28,7 @@ LL |         pub const _: () = {};
 LL | foo!();
    | ------ in this macro invocation
    |
-   = note: there is no declared name for the qualifier to affect
+   = note: `const _` does not declare a name, so there is nothing for the qualifier to apply to
    = note: this warning originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 warning: 3 warnings emitted