Use crate:: prefix for root macro suggestions

Author: bvanjoi

compiler/rustc_resolve/src/diagnostics.rs

@@ -2493,7 +2493,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         let Res::Def(DefKind::Macro(MacroKind::Bang), _) = binding.res() else {
             return None;
         };
-        let module_name = crate_module.kind.name().unwrap_or(kw::Empty);
+        let module_name = crate_module.kind.name().unwrap_or(kw::Crate);
         let import_snippet = match import.kind {
             ImportKind::Single { source, target, .. } if source != target => {
                 format!("{source} as {target}")

tests/ui/imports/issue-99695-b.fixed renamed to tests/ui/imports/issue-99695-b.edition_2015.fixed

@@ -1,4 +1,8 @@
 //@ run-rustfix
+//@ revisions: edition_2015 edition_2018
+//@ [edition_2015] edition: 2015
+//@ [edition_2018] edition: 2018
+
 #![allow(unused, nonstandard_style)]
 mod m {
 
@@ -11,7 +15,7 @@ mod m {
         pub struct other_item;
     }
 
-    use ::nu;
+    use crate::nu;
 pub use self::p::{other_item as _};
     //~^ ERROR unresolved import `self::p::nu` [E0432]
     //~| HELP a macro with this name exists at the root of the crate

tests/ui/imports/issue-99695-b.stderr renamed to tests/ui/imports/issue-99695-b.edition_2015.stderr

@@ -1,13 +1,13 @@
 error[E0432]: unresolved import `self::p::nu`
-  --> $DIR/issue-99695-b.rs:14:23
+  --> $DIR/issue-99695-b.rs:18:23
    |
 LL |     pub use self::p::{nu, other_item as _};
    |                       ^^ no `nu` in `m::p`
    |
    = note: this could be because a macro annotated with `#[macro_export]` will be exported at the root of the crate instead of the module where it is defined
 help: a macro with this name exists at the root of the crate
    |
-LL ~     use ::nu;
+LL ~     use crate::nu;
 LL ~ pub use self::p::{other_item as _};
    |
 

tests/ui/imports/issue-99695-b.edition_2018.fixed

@@ -0,0 +1,24 @@
+//@ run-rustfix
+//@ revisions: edition_2015 edition_2018
+//@ [edition_2015] edition: 2015
+//@ [edition_2018] edition: 2018
+
+#![allow(unused, nonstandard_style)]
+mod m {
+
+    mod p {
+        #[macro_export]
+        macro_rules! nu {
+            {} => {};
+        }
+
+        pub struct other_item;
+    }
+
+    use crate::nu;
+pub use self::p::{other_item as _};
+    //~^ ERROR unresolved import `self::p::nu` [E0432]
+    //~| HELP a macro with this name exists at the root of the crate
+}
+
+fn main() {}

tests/ui/imports/issue-99695-b.edition_2018.stderr

@@ -0,0 +1,16 @@
+error[E0432]: unresolved import `self::p::nu`
+  --> $DIR/issue-99695-b.rs:18:23
+   |
+LL |     pub use self::p::{nu, other_item as _};
+   |                       ^^ no `nu` in `m::p`
+   |
+   = note: this could be because a macro annotated with `#[macro_export]` will be exported at the root of the crate instead of the module where it is defined
+help: a macro with this name exists at the root of the crate
+   |
+LL ~     use crate::nu;
+LL ~ pub use self::p::{other_item as _};
+   |
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0432`.

tests/ui/imports/issue-99695-b.rs

@@ -1,4 +1,8 @@
 //@ run-rustfix
+//@ revisions: edition_2015 edition_2018
+//@ [edition_2015] edition: 2015
+//@ [edition_2018] edition: 2018
+
 #![allow(unused, nonstandard_style)]
 mod m {
 

tests/ui/imports/issue-99695.fixed

@@ -8,7 +8,7 @@ mod m {
 
     pub struct other_item;
 
-    use ::nu;
+    use crate::nu;
 pub use self::{other_item as _};
     //~^ ERROR unresolved import `self::nu` [E0432]
     //~| HELP a macro with this name exists at the root of the crate

tests/ui/imports/issue-99695.stderr

@@ -7,7 +7,7 @@ LL |     pub use self::{nu, other_item as _};
    = note: this could be because a macro annotated with `#[macro_export]` will be exported at the root of the crate instead of the module where it is defined
 help: a macro with this name exists at the root of the crate
    |
-LL ~     use ::nu;
+LL ~     use crate::nu;
 LL ~ pub use self::{other_item as _};
    |