Replacing self overwriting with proper resolution

compiler/rustc_resolve/src/build_reduced_graph.rs

@@ -622,42 +622,42 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
 
         match use_tree.kind {
             ast::UseTreeKind::Simple(rename) => {
-                let mut ident = use_tree.ident();
                 let mut module_path = prefix;
-                let mut source = module_path.pop().unwrap();
+                let source = module_path.pop().unwrap();
 
                 // `true` for `...::{self [as target]}` imports, `false` otherwise.
                 let type_ns_only = nested && source.ident.name == kw::SelfLower;
 
+                // Suggest `use prefix::{self};` for `use prefix::self;`
                 if source.ident.name == kw::SelfLower
-                    && let Some(parent) = module_path.pop()
+                    && let Some(parent) = module_path.last()
+                    && !type_ns_only
+                    && (parent.ident.name != kw::PathRoot
+                        || self.r.path_root_is_crate_root(parent.ident))
                 {
-                    // Suggest `use prefix::{self};` for `use prefix::self;`
-                    if !type_ns_only
-                        && (parent.ident.name != kw::PathRoot
-                            || self.r.path_root_is_crate_root(parent.ident))
-                    {
-                        let span_with_rename = match rename {
-                            Some(rename) => source.ident.span.to(rename.span),
-                            None => source.ident.span,
-                        };
-
-                        self.r.report_error(
-                            parent.ident.span.shrink_to_hi().to(source.ident.span),
-                            ResolutionError::SelfImportsOnlyAllowedWithin {
-                                root: parent.ident.name == kw::PathRoot,
-                                span_with_rename,
-                            },
-                        );
-                    }
+                    let span_with_rename = match rename {
+                        Some(rename) => source.ident.span.to(rename.span),
+                        None => source.ident.span,
+                    };
 
-                    let self_span = source.ident.span;
-                    source = parent;
-                    if rename.is_none() {
-                        ident = Ident::new(source.ident.name, self_span);
-                    }
+                    self.r.report_error(
+                        parent.ident.span.shrink_to_hi().to(source.ident.span),
+                        ResolutionError::SelfImportsOnlyAllowedWithin {
+                            root: parent.ident.name == kw::PathRoot,
+                            span_with_rename,
+                        },
+                    );
                 }
 
+                let ident = if source.ident.name == kw::SelfLower
+                    && rename.is_none()
+                    && let Some(parent) = module_path.last()
+                {
+                    Ident::new(parent.ident.name, source.ident.span)
+                } else {
+                    use_tree.ident()
+                };
+
                 match source.ident.name {
                     kw::DollarCrate => {
                         if !module_path.is_empty() {
@@ -694,7 +694,11 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> {
                         }
                     }
                     // Deny `use ::{self};` after edition 2015
-                    kw::PathRoot if !self.r.path_root_is_crate_root(source.ident) => {
+                    kw::SelfLower
+                        if let Some(parent) = module_path.last()
+                            && parent.ident.name == kw::PathRoot
+                            && !self.r.path_root_is_crate_root(parent.ident) =>
+                    {
                         self.r.dcx().span_err(use_tree.span, "extern prelude cannot be imported");
                         return;
                     }

compiler/rustc_resolve/src/ident.rs

@@ -953,12 +953,16 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
     ) -> Result<Decl<'ra>, Determinacy> {
         match module {
             ModuleOrUniformRoot::Module(module) => {
-                if ns == TypeNS
-                    && ident.name == kw::Super
-                    && let Some(module) =
-                        self.resolve_super_in_module(ident, Some(module), parent_scope)
-                {
-                    return Ok(module.self_decl.unwrap());
+                if ns == TypeNS {
+                    if ident.name == kw::SelfLower {
+                        return Ok(module.self_decl.unwrap());
+                    }
+                    if ident.name == kw::Super
+                        && let Some(module) =
+                            self.resolve_super_in_module(ident, Some(module), parent_scope)
+                    {
+                        return Ok(module.self_decl.unwrap());
+                    }
                 }
 
                 let (ident_key, def) = IdentKey::new_adjusted(ident, module.expansion);
@@ -1018,7 +1022,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                     {
                         let module = self.resolve_crate_root(ident);
                         return Ok(module.self_decl.unwrap());
-                    } else if ident.name == kw::Super || ident.name == kw::SelfLower {
+                    } else if ident.name == kw::Super {
                         // FIXME: Implement these with renaming requirements so that e.g.
                         // `use super;` doesn't work, but `use super as name;` does.
                         // Fall through here to get an error from `early_resolve_...`.

tests/ui/imports/cycle-import-in-std-1.stderr

@@ -1,11 +1,13 @@
 error[E0432]: unresolved import `ops`
-  --> $DIR/cycle-import-in-std-1.rs:5:11
+  --> $DIR/cycle-import-in-std-1.rs:5:5
    |
 LL | use ops::{self as std};
-   |           ^^^^^^^^^^^ no external crate `ops`
+   |     ^^^
    |
-   = help: consider importing this module instead:
-           std::ops
+help: a similar path exists
+   |
+LL | use core::ops::{self as std};
+   |     ++++++
 
 error: aborting due to 1 previous error
 

tests/ui/imports/cycle-import-in-std-2.stderr

@@ -1,11 +1,13 @@
 error[E0432]: unresolved import `ops`
-  --> $DIR/cycle-import-in-std-2.rs:5:11
+  --> $DIR/cycle-import-in-std-2.rs:5:5
    |
 LL | use ops::{self as std};
-   |           ^^^^^^^^^^^ no external crate `ops`
+   |     ^^^
    |
-   = help: consider importing this module instead:
-           std::ops
+help: a similar path exists
+   |
+LL | use core::ops::{self as std};
+   |     ++++++
 
 error: aborting due to 1 previous error
 

tests/ui/imports/issue-28388-1.stderr

@@ -2,7 +2,12 @@ error[E0432]: unresolved import `foo`
   --> $DIR/issue-28388-1.rs:4:5
    |
 LL | use foo::{};
-   |     ^^^^^^^ no `foo` in the root
+   |     ^^^ use of unresolved module or unlinked crate `foo`
+   |
+help: you might be missing a crate named `foo`, add it to your project and import it in your code
+   |
+LL + extern crate foo;
+   |
 
 error: aborting due to 1 previous error
 

tests/ui/imports/issue-38293.stderr

@@ -1,8 +1,8 @@
 error[E0432]: unresolved import `foo::f`
-  --> $DIR/issue-38293.rs:7:14
+  --> $DIR/issue-38293.rs:7:10
    |
 LL | use foo::f::{self};
-   |              ^^^^ no `f` in `foo`
+   |          ^ expected type, found function `f` in `foo`
 
 error[E0423]: expected function, found module `baz`
   --> $DIR/issue-38293.rs:16:5

tests/ui/imports/issue-45829/import-self.stderr

@@ -47,9 +47,8 @@ LL | use foo::self;
    = note: `foo` must be defined only once in the type namespace of this module
 help: you can use `as` to change the binding name of the import
    |
-LL - use foo::self;
-LL + use foo as other_foo;
-   |
+LL | use foo::self as other_foo;
+   |               ++++++++++++
 
 error[E0252]: the name `A` is defined multiple times
   --> $DIR/import-self.rs:16:11

tests/ui/privacy/private-variant-reexport.rs

@@ -8,7 +8,7 @@ mod m2 {
 }
 
 mod m3 {
-    pub use ::E::V::{self}; //~ ERROR `V` is only public within the crate, and cannot be re-exported outside
+    pub use ::E::V::{self}; //~ ERROR unresolved import `E::V`
 }
 
 #[deny(unused_imports)]

tests/ui/privacy/private-variant-reexport.stderr

@@ -22,13 +22,11 @@ note: consider marking `V` as `pub` in the imported module
 LL |     pub use ::E::{V};
    |                   ^
 
-error[E0365]: `V` is only public within the crate, and cannot be re-exported outside
-  --> $DIR/private-variant-reexport.rs:11:22
+error[E0432]: unresolved import `E::V`
+  --> $DIR/private-variant-reexport.rs:11:18
    |
 LL |     pub use ::E::V::{self};
-   |                      ^^^^ re-export of crate public `V`
-   |
-   = note: consider declaring type or module `V` with `pub`
+   |                  ^ `V` is a variant, not a module
 
 error: glob import doesn't reexport anything with visibility `pub` because no imported item is public enough
   --> $DIR/private-variant-reexport.rs:16:13
@@ -56,5 +54,5 @@ LL |     pub use ::E::*;
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0364, E0365.
+Some errors have detailed explanations: E0364, E0432.
 For more information about an error, try `rustc --explain E0364`.

tests/ui/resolve/resolve-bad-import-prefix.rs

@@ -8,7 +8,7 @@ use {}; // OK
 use ::{}; // OK
 use m::{}; // OK
 use E::{}; // OK
-use S::{}; // FIXME, this and `use S::{self};` should be an error
+use S::{}; //~ ERROR unresolved import `S`
 use Tr::{}; // FIXME, this and `use Tr::{self};` should be an error
 use Nonexistent::{}; //~ ERROR unresolved import `Nonexistent`
 

tests/ui/resolve/resolve-bad-import-prefix.stderr

@@ -1,9 +1,20 @@
+error[E0432]: unresolved import `S`
+  --> $DIR/resolve-bad-import-prefix.rs:11:5
+   |
+LL | use S::{};
+   |     ^ `S` is a struct, not a module
+
 error[E0432]: unresolved import `Nonexistent`
   --> $DIR/resolve-bad-import-prefix.rs:13:5
    |
 LL | use Nonexistent::{};
-   |     ^^^^^^^^^^^^^^^ no `Nonexistent` in the root
+   |     ^^^^^^^^^^^ use of unresolved module or unlinked crate `Nonexistent`
+   |
+help: you might be missing a crate named `Nonexistent`, add it to your project and import it in your code
+   |
+LL + extern crate Nonexistent;
+   |
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0432`.

tests/ui/use/use-mod/use-mod-4.stderr

@@ -31,10 +31,15 @@ LL | use std::mem::{self};
    |               +    +
 
 error[E0432]: unresolved import `crate::foo`
-  --> $DIR/use-mod-4.rs:1:5
+  --> $DIR/use-mod-4.rs:1:12
    |
 LL | use crate::foo::self;
-   |     ^^^^^^^^^^^^^^^^ no `foo` in the root
+   |            ^^^ use of unresolved module or unlinked crate `foo`
+   |
+help: you might be missing a crate named `foo`, add it to your project and import it in your code
+   |
+LL + extern crate foo;
+   |
 
 error: aborting due to 3 previous errors
 

tests/ui/use/use-path-segment-kw.e2015.stderr

@@ -935,39 +935,49 @@ help: try renaming it with a name
 LL |         use $crate::{self as name};
    |                           +++++++
 
-error[E0432]: unresolved import `foobar`
+error[E0433]: cannot find module or crate `foobar` in the crate root
   --> $DIR/use-path-segment-kw.rs:187:17
    |
 LL |         pub use foobar::qux::self;
-   |                 ^^^^^^
+   |                 ^^^^^^ use of unresolved module or unlinked crate `foobar`
    |
-help: a similar path exists
+help: you might be missing a crate named `foobar`, add it to your project and import it in your code
    |
-LL |         pub use self::foobar::qux::self;
-   |                 ++++++
-
-error[E0432]: unresolved import `foobar`
-  --> $DIR/use-path-segment-kw.rs:189:17
+LL + extern crate foobar;
    |
-LL |         pub use foobar::self as _self3;
-   |                 ^^^^^^^^^^^^^^^^^^^^^^ no `foobar` in the root
 
-error[E0432]: unresolved import `foobar`
+error[E0433]: cannot find module or crate `foobar` in the crate root
   --> $DIR/use-path-segment-kw.rs:191:17
    |
 LL |         pub use foobar::baz::{self};
+   |                 ^^^^^^ use of unresolved module or unlinked crate `foobar`
+   |
+help: you might be missing a crate named `foobar`, add it to your project and import it in your code
+   |
+LL + extern crate foobar;
+   |
+
+error[E0432]: unresolved import `foobar`
+  --> $DIR/use-path-segment-kw.rs:189:17
+   |
+LL |         pub use foobar::self as _self3;
    |                 ^^^^^^
    |
 help: a similar path exists
    |
-LL |         pub use self::foobar::baz::{self};
+LL |         pub use self::foobar::self as _self3;
    |                 ++++++
 
 error[E0432]: unresolved import `foobar`
-  --> $DIR/use-path-segment-kw.rs:192:26
+  --> $DIR/use-path-segment-kw.rs:192:17
    |
 LL |         pub use foobar::{self as _nested_self3};
-   |                          ^^^^^^^^^^^^^^^^^^^^^ no `foobar` in the root
+   |                 ^^^^^^
+   |
+help: a similar path exists
+   |
+LL |         pub use self::foobar::{self as _nested_self3};
+   |                 ++++++
 
 error[E0433]: `self` in paths can only be used in start position
   --> $DIR/use-path-segment-kw.rs:215:36

tests/ui/use/use-path-segment-kw.rs

@@ -185,10 +185,10 @@ mod foo {
 
         type D3 = foobar::self; //~ ERROR `self` in paths can only be used in start position
         pub use foobar::qux::self; //~ ERROR `self` imports are only allowed within a { } list
-        //[e2015]~^ ERROR unresolved import `foobar`
+        //[e2015]~^ ERROR cannot find module or crate `foobar` in the crate root
         pub use foobar::self as _self3; //~ ERROR `self` imports are only allowed within a { } list
         //[e2015]~^ ERROR unresolved import `foobar`
-        pub use foobar::baz::{self}; //[e2015]~ ERROR unresolved import `foobar`
+        pub use foobar::baz::{self}; //[e2015]~ ERROR cannot find module or crate `foobar` in the crate root
         pub use foobar::{self as _nested_self3}; //[e2015]~ ERROR unresolved import `foobar`
 
         type D4 = crate::self; //~ ERROR `self` in paths can only be used in start position