Rollup merge of rust-lang#119925 - bvanjoi:fix-112672, r=Nilstrieb

store the segment name when resolution fails

Fixes rust-lang#112672

The `find_cfg_stripped` does indeed get executed within `smart_resolve_report_errors`. However, this error is not reported as it is subsequently overridden by `parent_err`. (See: https://github.com/rust-lang/rust/blob/master/compiler/rustc_resolve/src/late.rs#L3760)

This PR changes `last_segment` to `segment`, which stores the name of the failed resolution, and ensures that the result of `find_cfg_stripped` is also included in `parent_err`.

r? ```@Nilstrieb```

Author: matthiaskrgr

Diff for: compiler/rustc_resolve/src/diagnostics.rs

@@ -786,7 +786,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             ResolutionError::SelfImportOnlyInImportListWithNonEmptyPrefix => {
                 self.dcx().create_err(errs::SelfImportOnlyInImportListWithNonEmptyPrefix { span })
             }
-            ResolutionError::FailedToResolve { last_segment, label, suggestion, module } => {
+            ResolutionError::FailedToResolve { segment, label, suggestion, module } => {
                 let mut err =
                     struct_span_code_err!(self.dcx(), span, E0433, "failed to resolve: {}", &label);
                 err.span_label(span, label);
@@ -801,9 +801,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
                 if let Some(ModuleOrUniformRoot::Module(module)) = module
                     && let Some(module) = module.opt_def_id()
-                    && let Some(last_segment) = last_segment
+                    && let Some(segment) = segment
                 {
-                    self.find_cfg_stripped(&mut err, &last_segment, module);
+                    self.find_cfg_stripped(&mut err, &segment, module);
                 }
 
                 err
@@ -981,12 +981,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
             VisResolutionError::FailedToResolve(span, label, suggestion) => self.into_struct_error(
                 span,
-                ResolutionError::FailedToResolve {
-                    last_segment: None,
-                    label,
-                    suggestion,
-                    module: None,
-                },
+                ResolutionError::FailedToResolve { segment: None, label, suggestion, module: None },
             ),
             VisResolutionError::ExpectedFound(span, path_str, res) => {
                 self.dcx().create_err(errs::ExpectedFound { span, res, path_str })
@@ -2450,7 +2445,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
     pub(crate) fn find_cfg_stripped(
         &mut self,
         err: &mut Diagnostic,
-        last_segment: &Symbol,
+        segment: &Symbol,
         module: DefId,
     ) {
         let local_items;
@@ -2469,7 +2464,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         };
 
         for &StrippedCfgItem { parent_module, name, ref cfg } in symbols {
-            if parent_module != module || name.name != *last_segment {
+            if parent_module != module || name.name != *segment {
                 continue;
             }
 

Diff for: compiler/rustc_resolve/src/ident.rs

@@ -1381,13 +1381,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                             continue;
                         }
                     }
-                    return PathResult::failed(
-                        ident.span,
-                        false,
-                        finalize.is_some(),
-                        module,
-                        || ("there are too many leading `super` keywords".to_string(), None),
-                    );
+                    return PathResult::failed(ident, false, finalize.is_some(), module, || {
+                        ("there are too many leading `super` keywords".to_string(), None)
+                    });
                 }
                 if segment_idx == 0 {
                     if name == kw::SelfLower {
@@ -1419,7 +1415,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
             // Report special messages for path segment keywords in wrong positions.
             if ident.is_path_segment_keyword() && segment_idx != 0 {
-                return PathResult::failed(ident.span, false, finalize.is_some(), module, || {
+                return PathResult::failed(ident, false, finalize.is_some(), module, || {
                     let name_str = if name == kw::PathRoot {
                         "crate root".to_string()
                     } else {
@@ -1515,7 +1511,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         ));
                     } else {
                         return PathResult::failed(
-                            ident.span,
+                            ident,
                             is_last,
                             finalize.is_some(),
                             module,
@@ -1541,24 +1537,18 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         }
                     }
 
-                    return PathResult::failed(
-                        ident.span,
-                        is_last,
-                        finalize.is_some(),
-                        module,
-                        || {
-                            self.report_path_resolution_error(
-                                path,
-                                opt_ns,
-                                parent_scope,
-                                ribs,
-                                ignore_binding,
-                                module,
-                                segment_idx,
-                                ident,
-                            )
-                        },
-                    );
+                    return PathResult::failed(ident, is_last, finalize.is_some(), module, || {
+                        self.report_path_resolution_error(
+                            path,
+                            opt_ns,
+                            parent_scope,
+                            ribs,
+                            ignore_binding,
+                            module,
+                            segment_idx,
+                            ident,
+                        )
+                    });
                 }
             }
         }

Diff for: compiler/rustc_resolve/src/imports.rs

@@ -886,6 +886,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             PathResult::Failed {
                 is_error_from_last_segment: false,
                 span,
+                segment_name,
                 label,
                 suggestion,
                 module,
@@ -895,7 +896,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     self.report_error(
                         span,
                         ResolutionError::FailedToResolve {
-                            last_segment: None,
+                            segment: Some(segment_name),
                             label,
                             suggestion,
                             module,

Diff for: compiler/rustc_resolve/src/late.rs

@@ -4054,11 +4054,12 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 label,
                 suggestion,
                 module,
+                segment_name,
             } => {
                 return Err(respan(
                     span,
                     ResolutionError::FailedToResolve {
-                        last_segment: None,
+                        segment: Some(segment_name),
                         label,
                         suggestion,
                         module,

Diff for: compiler/rustc_resolve/src/lib.rs

@@ -213,7 +213,7 @@ enum ResolutionError<'a> {
     SelfImportOnlyInImportListWithNonEmptyPrefix,
     /// Error E0433: failed to resolve.
     FailedToResolve {
-        last_segment: Option<Symbol>,
+        segment: Option<Symbol>,
         label: String,
         suggestion: Option<Suggestion>,
         module: Option<ModuleOrUniformRoot<'a>>,
@@ -396,20 +396,29 @@ enum PathResult<'a> {
         suggestion: Option<Suggestion>,
         is_error_from_last_segment: bool,
         module: Option<ModuleOrUniformRoot<'a>>,
+        /// The segment name of target
+        segment_name: Symbol,
     },
 }
 
 impl<'a> PathResult<'a> {
     fn failed(
-        span: Span,
+        ident: Ident,
         is_error_from_last_segment: bool,
         finalize: bool,
         module: Option<ModuleOrUniformRoot<'a>>,
         label_and_suggestion: impl FnOnce() -> (String, Option<Suggestion>),
     ) -> PathResult<'a> {
         let (label, suggestion) =
             if finalize { label_and_suggestion() } else { (String::new(), None) };
-        PathResult::Failed { span, label, suggestion, is_error_from_last_segment, module }
+        PathResult::Failed {
+            span: ident.span,
+            segment_name: ident.name,
+            label,
+            suggestion,
+            is_error_from_last_segment,
+            module,
+        }
     }
 }
 

Diff for: compiler/rustc_resolve/src/macros.rs

@@ -779,7 +779,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     self.report_error(
                         span,
                         ResolutionError::FailedToResolve {
-                            last_segment: path.last().map(|segment| segment.ident.name),
+                            segment: path.last().map(|segment| segment.ident.name),
                             label,
                             suggestion,
                             module,

Diff for: tests/ui/cfg/diagnostics-cross-crate.rs

@@ -14,9 +14,9 @@ fn main() {
 
     // The module isn't found - we would like to get a diagnostic, but currently don't due to
     // the awkward way the resolver diagnostics are currently implemented.
-    // FIXME(Nilstrieb): Also add a note to the cfg diagnostic here
     cfged_out::inner::doesnt_exist::hello(); //~ ERROR failed to resolve
     //~^ NOTE could not find `doesnt_exist` in `inner`
+    //~| NOTE found an item that was configured out
 
     // It should find the one in the right module, not the wrong one.
     cfged_out::inner::right::meow(); //~ ERROR cannot find function

Diff for: tests/ui/cfg/diagnostics-cross-crate.stderr

@@ -1,8 +1,14 @@
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-cross-crate.rs:18:23
+  --> $DIR/diagnostics-cross-crate.rs:17:23
    |
 LL |     cfged_out::inner::doesnt_exist::hello();
    |                       ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
+   |
+note: found an item that was configured out
+  --> $DIR/auxiliary/cfged_out.rs:6:13
+   |
+LL |     pub mod doesnt_exist {
+   |             ^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in crate `cfged_out`
   --> $DIR/diagnostics-cross-crate.rs:7:16

Diff for: tests/ui/cfg/diagnostics-same-crate.rs

@@ -4,7 +4,7 @@ pub mod inner {
     //~^ NOTE found an item that was configured out
 
     #[cfg(FALSE)]
-    pub mod doesnt_exist {
+    pub mod doesnt_exist { //~ NOTE found an item that was configured out
         pub fn hello() {}
     }
 
@@ -34,7 +34,6 @@ fn main() {
 
     // The module isn't found - we would like to get a diagnostic, but currently don't due to
     // the awkward way the resolver diagnostics are currently implemented.
-    // FIXME(Nilstrieb): Also add a note to the cfg diagnostic here
     inner::doesnt_exist::hello(); //~ ERROR failed to resolve
     //~| NOTE could not find `doesnt_exist` in `inner`
 

Diff for: tests/ui/cfg/diagnostics-same-crate.stderr

@@ -1,8 +1,14 @@
 error[E0433]: failed to resolve: could not find `doesnt_exist` in `inner`
-  --> $DIR/diagnostics-same-crate.rs:38:12
+  --> $DIR/diagnostics-same-crate.rs:37:12
    |
 LL |     inner::doesnt_exist::hello();
    |            ^^^^^^^^^^^^ could not find `doesnt_exist` in `inner`
+   |
+note: found an item that was configured out
+  --> $DIR/diagnostics-same-crate.rs:7:13
+   |
+LL |     pub mod doesnt_exist {
+   |             ^^^^^^^^^^^^
 
 error[E0425]: cannot find function `uwu` in module `inner`
   --> $DIR/diagnostics-same-crate.rs:32:12
@@ -17,7 +23,7 @@ LL |     pub fn uwu() {}
    |            ^^^
 
 error[E0425]: cannot find function `meow` in module `inner::right`
-  --> $DIR/diagnostics-same-crate.rs:42:19
+  --> $DIR/diagnostics-same-crate.rs:41:19
    |
 LL |     inner::right::meow();
    |                   ^^^^ not found in `inner::right`
@@ -36,7 +42,7 @@ LL |     uwu();
    |     ^^^ not found in this scope
 
 error[E0425]: cannot find function `vanished` in this scope
-  --> $DIR/diagnostics-same-crate.rs:49:5
+  --> $DIR/diagnostics-same-crate.rs:48:5
    |
 LL |     vanished();
    |     ^^^^^^^^ not found in this scope