Emit error UnnamedCrateRootImport also for DollarCrate

Author: mu001999

compiler/rustc_resolve/messages.ftl

@@ -461,7 +461,10 @@ resolve_unexpected_res_use_at_op_in_slice_pat_with_range_sugg =
     if you meant to collect the rest of the slice in `{$ident}`, use the at operator
 
 resolve_unnamed_crate_root_import =
-    crate root imports need to be explicitly named: `use crate as name;`
+    {$dollar ->
+        [true] crate root imports need to be explicitly named: `use $crate as name;`
+        *[false] crate root imports need to be explicitly named: `use crate as name;`
+    }
 
 resolve_unreachable_label =
     use of unreachable label `{$name}`

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -651,8 +651,11 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                     }
                 }
 
-                if ident.name == kw::Crate {
-                    self.r.dcx().emit_err(errors::UnnamedCrateRootImport { span: ident.span });
+                if ident.name == kw::Crate || ident.name == kw::DollarCrate {
+                    self.r.dcx().emit_err(errors::UnnamedCrateRootImport {
+                        span: ident.span,
+                        dollar: ident.name == kw::DollarCrate,
+                    });
                 }
 
                 let kind = ImportKind::Single {

compiler/rustc_resolve/src/errors.rs

@@ -896,6 +896,7 @@ pub(crate) struct ArgumentsMacroUseNotAllowed {
 pub(crate) struct UnnamedCrateRootImport {
     #[primary_span]
     pub(crate) span: Span,
+    pub(crate) dollar: bool,
 }
 
 #[derive(Diagnostic)]

tests/ui/dollar-crate/dollar-crate-is-keyword-2.rs

@@ -3,6 +3,7 @@ mod a {}
 macro_rules! m {
     () => {
         use a::$crate; //~ ERROR unresolved import `a::$crate`
+        //~^ ERROR crate root imports need to be explicitly named: `use $crate as name;`
         use a::$crate::b; //~ ERROR `$crate` in paths can only be used in start position
         type A = a::$crate; //~ ERROR `$crate` in paths can only be used in start position
     }

tests/ui/dollar-crate/dollar-crate-is-keyword-2.stderr

@@ -1,5 +1,16 @@
+error: crate root imports need to be explicitly named: `use $crate as name;`
+  --> $DIR/dollar-crate-is-keyword-2.rs:5:16
+   |
+LL |         use a::$crate;
+   |                ^^^^^^
+...
+LL | m!();
+   | ---- in this macro invocation
+   |
+   = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
+
 error[E0433]: failed to resolve: `$crate` in paths can only be used in start position
-  --> $DIR/dollar-crate-is-keyword-2.rs:6:16
+  --> $DIR/dollar-crate-is-keyword-2.rs:7:16
    |
 LL |         use a::$crate::b;
    |                ^^^^^^ `$crate` in paths can only be used in start position
@@ -21,7 +32,7 @@ LL | m!();
    = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0433]: failed to resolve: `$crate` in paths can only be used in start position
-  --> $DIR/dollar-crate-is-keyword-2.rs:7:21
+  --> $DIR/dollar-crate-is-keyword-2.rs:8:21
    |
 LL |         type A = a::$crate;
    |                     ^^^^^^ `$crate` in paths can only be used in start position
@@ -31,7 +42,7 @@ LL | m!();
    |
    = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 3 previous errors
+error: aborting due to 4 previous errors
 
 Some errors have detailed explanations: E0432, E0433.
 For more information about an error, try `rustc --explain E0432`.

tests/ui/dollar-crate/dollar-crate-is-keyword.rs

@@ -9,6 +9,7 @@ macro_rules! m {
         use $crate; //~ ERROR `$crate` may not be imported
         use $crate as $crate; //~ ERROR expected identifier, found reserved identifier `$crate`
         //~^ ERROR `$crate` may not be imported
+        //~^^ ERROR crate root imports need to be explicitly named: `use $crate as name;`
     }
 }
 

tests/ui/dollar-crate/dollar-crate-is-keyword.stderr

@@ -42,5 +42,16 @@ LL | m!();
    |
    = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 4 previous errors
+error: crate root imports need to be explicitly named: `use $crate as name;`
+  --> $DIR/dollar-crate-is-keyword.rs:10:23
+   |
+LL |         use $crate as $crate;
+   |                       ^^^^^^
+...
+LL | m!();
+   | ---- in this macro invocation
+   |
+   = note: this error originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 5 previous errors
 

tests/ui/macros/use-dollar-crate.rs

@@ -0,0 +1,9 @@
+macro_rules! foo {
+    () => {
+        use $crate::{self}; //~ ERROR crate root imports need to be explicitly named: `use $crate as name;`
+    };
+}
+
+foo!();
+
+fn main() {}

tests/ui/macros/use-dollar-crate.stderr

@@ -0,0 +1,13 @@
+error: crate root imports need to be explicitly named: `use $crate as name;`
+  --> $DIR/use-dollar-crate.rs:3:22
+   |
+LL |         use $crate::{self};
+   |                      ^^^^
+...
+LL | foo!();
+   | ------ in this macro invocation
+   |
+   = note: this error originates in the macro `foo` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 1 previous error
+