Implement a Method to Seal DiagInner's Suggestions

Author: veera-sivarajan

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -16,7 +16,7 @@ use rustc_errors::emitter::Emitter;
 use rustc_errors::translation::Translate;
 use rustc_errors::{
     Diag, DiagArgMap, DiagCtxt, DiagMessage, ErrCode, FatalError, FluentBundle, Level, MultiSpan,
-    Style,
+    Style, Suggestions,
 };
 use rustc_fs_util::link_or_copy;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
@@ -1903,7 +1903,7 @@ impl Emitter for SharedEmitter {
         // Check that we aren't missing anything interesting when converting to
         // the cut-down local `DiagInner`.
         assert_eq!(diag.span, MultiSpan::new());
-        assert_eq!(diag.suggestions, Ok(vec![]));
+        assert_eq!(diag.suggestions, Suggestions::Enabled(vec![]));
         assert_eq!(diag.sort_span, rustc_span::DUMMY_SP);
         assert_eq!(diag.is_lint, None);
         // No sensible check for `diag.emitted_at`.

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -48,7 +48,7 @@ impl Emitter for AnnotateSnippetEmitter {
     fn emit_diagnostic(&mut self, mut diag: DiagInner) {
         let fluent_args = to_fluent_args(diag.args.iter());
 
-        let mut suggestions = diag.suggestions.unwrap_or(vec![]);
+        let mut suggestions = diag.suggestions.unwrap_tag();
         self.primary_span_formatted(&mut diag.span, &mut suggestions, &fluent_args);
 
         self.fix_multispans_in_extern_macros_and_render_macro_backtrace(

compiler/rustc_errors/src/diagnostic.rs

@@ -19,13 +19,9 @@ use crate::snippet::Style;
 use crate::{
     CodeSuggestion, DiagCtxtHandle, DiagMessage, ErrCode, ErrorGuaranteed, ExplicitBug, Level,
     MultiSpan, StashKey, SubdiagMessage, Substitution, SubstitutionPart, SuggestionStyle,
+    Suggestions,
 };
 
-/// Error type for `DiagInner`'s `suggestions` field, indicating that
-/// `.disable_suggestions()` was called on the `DiagInner`.
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
-pub struct SuggestionsDisabled;
-
 /// Simplified version of `FluentArg` that can implement `Encodable` and `Decodable`. Collection of
 /// `DiagArg` are converted to `FluentArgs` (consuming the collection) at the start of diagnostic
 /// emission.
@@ -296,7 +292,7 @@ pub struct DiagInner {
     pub code: Option<ErrCode>,
     pub span: MultiSpan,
     pub children: Vec<Subdiag>,
-    pub suggestions: Result<Vec<CodeSuggestion>, SuggestionsDisabled>,
+    pub suggestions: Suggestions,
     pub args: DiagArgMap,
 
     /// This is not used for highlighting or rendering any error message. Rather, it can be used
@@ -325,7 +321,7 @@ impl DiagInner {
             code: None,
             span: MultiSpan::new(),
             children: vec![],
-            suggestions: Ok(vec![]),
+            suggestions: Suggestions::Enabled(vec![]),
             args: Default::default(),
             sort_span: DUMMY_SP,
             is_lint: None,
@@ -409,7 +405,7 @@ impl DiagInner {
         &Option<ErrCode>,
         &MultiSpan,
         &[Subdiag],
-        &Result<Vec<CodeSuggestion>, SuggestionsDisabled>,
+        &Suggestions,
         Vec<(&DiagArgName, &DiagArgValue)>,
         &Option<IsLint>,
     ) {
@@ -823,16 +819,32 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self
     }
 
-    /// Disallow attaching suggestions this diagnostic.
+    /// Disallow attaching suggestions to this diagnostic.
     /// Any suggestions attached e.g. with the `span_suggestion_*` methods
     /// (before and after the call to `disable_suggestions`) will be ignored.
     #[rustc_lint_diagnostics]
     pub fn disable_suggestions(&mut self) -> &mut Self {
-        self.suggestions = Err(SuggestionsDisabled);
+        self.suggestions = Suggestions::Disabled;
         self
     }
 
-    /// Helper for pushing to `self.suggestions`, if available (not disable).
+    /// Prevent new suggestions from being added to this diagnostic.
+    ///
+    /// Suggestions added before the call to `.seal_suggestions()` will be preserved
+    /// and new suggestions will be ignored.
+    #[rustc_lint_diagnostics]
+    pub fn seal_suggestions(&mut self) -> &mut Self {
+        if let Suggestions::Enabled(suggestions) = &mut self.suggestions {
+            let suggestions_slice = std::mem::take(suggestions).into_boxed_slice();
+            self.suggestions = Suggestions::Sealed(suggestions_slice);
+        }
+        self
+    }
+
+    /// Helper for pushing to `self.suggestions`.
+    ///
+    /// A new suggestion is added if suggestions are enabled for this diagnostic.
+    /// Otherwise, they are ignored.
     #[rustc_lint_diagnostics]
     fn push_suggestion(&mut self, suggestion: CodeSuggestion) {
         for subst in &suggestion.substitutions {
@@ -846,7 +858,7 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
             }
         }
 
-        if let Ok(suggestions) = &mut self.suggestions {
+        if let Suggestions::Enabled(suggestions) = &mut self.suggestions {
             suggestions.push(suggestion);
         }
     }

compiler/rustc_errors/src/emitter.rs

@@ -498,7 +498,7 @@ impl Emitter for HumanEmitter {
     fn emit_diagnostic(&mut self, mut diag: DiagInner) {
         let fluent_args = to_fluent_args(diag.args.iter());
 
-        let mut suggestions = diag.suggestions.unwrap_or(vec![]);
+        let mut suggestions = diag.suggestions.unwrap_tag();
         self.primary_span_formatted(&mut diag.span, &mut suggestions, &fluent_args);
 
         self.fix_multispans_in_extern_macros_and_render_macro_backtrace(

compiler/rustc_errors/src/json.rs

@@ -33,7 +33,8 @@ use crate::emitter::{
 use crate::registry::Registry;
 use crate::translation::{to_fluent_args, Translate};
 use crate::{
-    CodeSuggestion, FluentBundle, LazyFallbackBundle, MultiSpan, SpanLabel, Subdiag, TerminalUrl,
+    CodeSuggestion, FluentBundle, LazyFallbackBundle, MultiSpan, SpanLabel, Subdiag, Suggestions,
+    TerminalUrl,
 };
 
 #[cfg(test)]
@@ -292,7 +293,7 @@ impl Diagnostic {
     /// Converts from `rustc_errors::DiagInner` to `Diagnostic`.
     fn from_errors_diagnostic(diag: crate::DiagInner, je: &JsonEmitter) -> Diagnostic {
         let args = to_fluent_args(diag.args.iter());
-        let sugg = diag.suggestions.iter().flatten().map(|sugg| {
+        let sugg_to_diag = |sugg: &CodeSuggestion| {
             let translated_message =
                 je.translate_message(&sugg.msg, &args).map_err(Report::new).unwrap();
             Diagnostic {
@@ -303,7 +304,12 @@ impl Diagnostic {
                 children: vec![],
                 rendered: None,
             }
-        });
+        };
+        let sugg = match &diag.suggestions {
+            Suggestions::Enabled(suggestions) => suggestions.iter().map(sugg_to_diag),
+            Suggestions::Sealed(suggestions) => suggestions.iter().map(sugg_to_diag),
+            Suggestions::Disabled => [].iter().map(sugg_to_diag),
+        };
 
         // generate regular command line output and store it in the json
 

compiler/rustc_errors/src/lib.rs

@@ -126,6 +126,41 @@ impl SuggestionStyle {
     }
 }
 
+/// Represents the help messages seen on a diagnostic.
+#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
+pub enum Suggestions {
+    /// Indicates that new suggestions can be added or removed from this diagnostic.
+    ///
+    /// `DiagInner`'s new_* methods initialize the `suggestions` field with
+    /// this variant. Also, this is the default variant for `Suggestions`.
+    Enabled(Vec<CodeSuggestion>),
+    /// Indicates that suggestions cannot be added or removed from this diagnostic.
+    ///
+    /// Gets toggled when `.seal_suggestions()` is called on the `DiagInner`.
+    Sealed(Box<[CodeSuggestion]>),
+    /// Indicates that no suggestion is available for this diagnostic.
+    ///
+    /// Gets toggled when `.disable_suggestions()` is called on the `DiagInner`.
+    Disabled,
+}
+
+impl Suggestions {
+    /// Returns the underlying list of suggestions.
+    pub fn unwrap_tag(self) -> Vec<CodeSuggestion> {
+        match self {
+            Suggestions::Enabled(suggestions) => suggestions,
+            Suggestions::Sealed(suggestions) => suggestions.into_vec(),
+            Suggestions::Disabled => Vec::new(),
+        }
+    }
+}
+
+impl Default for Suggestions {
+    fn default() -> Self {
+        Self::Enabled(vec![])
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub struct CodeSuggestion {
     /// Each substitute can have multiple variants due to multiple

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -1,6 +1,6 @@
 use core::ops::ControlFlow;
 
-use rustc_errors::{Applicability, StashKey};
+use rustc_errors::{Applicability, StashKey, Suggestions};
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::HirId;
@@ -670,7 +670,7 @@ fn infer_placeholder_type<'tcx>(
 
                 // The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
                 // We are typeck and have the real type, so remove that and suggest the actual type.
-                if let Ok(suggestions) = &mut err.suggestions {
+                if let Suggestions::Enabled(suggestions) = &mut err.suggestions {
                     suggestions.clear();
                 }
 

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -16,7 +16,7 @@ use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{
     pluralize, Applicability, Diag, DiagCtxtHandle, ErrorGuaranteed, FatalError, PErr, PResult,
-    Subdiagnostic,
+    Subdiagnostic, Suggestions,
 };
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::edit_distance::find_best_match_for_name;
@@ -775,7 +775,7 @@ impl<'a> Parser<'a> {
         }
 
         // Check for misspelled keywords if there are no suggestions added to the diagnostic.
-        if err.suggestions.as_ref().is_ok_and(|code_suggestions| code_suggestions.is_empty()) {
+        if matches!(&err.suggestions, Suggestions::Enabled(list) if list.is_empty()) {
             self.check_for_misspelled_kw(&mut err, &expected);
         }
         Err(err)
@@ -803,6 +803,9 @@ impl<'a> Parser<'a> {
             && let Some(misspelled_kw) = find_similar_kw(curr_ident, &expected_keywords)
         {
             err.subdiagnostic(misspelled_kw);
+            // We don't want other suggestions to be added as they are most likely meaningless
+            // when there is a misspelled keyword.
+            err.seal_suggestions();
         } else if let Some((prev_ident, _)) = self.prev_token.ident()
             && !prev_ident.is_used_keyword()
         {
@@ -818,6 +821,9 @@ impl<'a> Parser<'a> {
             // positives like suggesting keyword `for` for `extern crate foo {}`.
             if let Some(misspelled_kw) = find_similar_kw(prev_ident, &all_keywords) {
                 err.subdiagnostic(misspelled_kw);
+                // We don't want other suggestions to be added as they are most likely meaningless
+                // when there is a misspelled keyword.
+                err.seal_suggestions();
             }
         }
     }

compiler/rustc_resolve/src/late.rs

@@ -17,7 +17,7 @@ use rustc_ast::visit::{visit_opt, walk_list, AssocCtxt, BoundKind, FnCtxt, FnKin
 use rustc_ast::*;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_errors::codes::*;
-use rustc_errors::{Applicability, DiagArgValue, IntoDiagArg, StashKey};
+use rustc_errors::{Applicability, DiagArgValue, IntoDiagArg, StashKey, Suggestions};
 use rustc_hir::def::Namespace::{self, *};
 use rustc_hir::def::{self, CtorKind, DefKind, LifetimeRes, NonMacroAttrKind, PartialRes, PerNS};
 use rustc_hir::def_id::{DefId, LocalDefId, CRATE_DEF_ID, LOCAL_CRATE};
@@ -4052,6 +4052,56 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                 err.sort_span = parent_err.sort_span;
                 err.is_lint = parent_err.is_lint.clone();
 
+                // merge the parent_err's suggestions with the typo (err's) suggestions
+                match &mut err.suggestions {
+                    Suggestions::Enabled(typo_suggestions) => match &mut parent_err.suggestions {
+                        Suggestions::Enabled(parent_suggestions) => {
+                            // If both suggestions are enabled, append parent_err's suggestions to err's suggestions.
+                            typo_suggestions.append(parent_suggestions)
+                        }
+                        Suggestions::Sealed(_) | Suggestions::Disabled => {
+                            // If the parent's suggestions are either sealed or disabled, it signifies that
+                            // new suggestions cannot be added or removed from the diagnostic. Therefore,
+                            // we assign both types of suggestions to err's suggestions and discard the
+                            // existing suggestions in err.
+                            err.suggestions = std::mem::take(&mut parent_err.suggestions);
+                        }
+                    },
+                    Suggestions::Sealed(_) | Suggestions::Disabled => (),
+                }
+
+                let (mut err, candidates) = this.smart_resolve_report_errors(
+                    prefix_path,
+                    following_seg,
+                    path_span,
+                    PathSource::Type,
+                    None,
+                );
+
+                // There are two different error messages user might receive at
+                // this point:
+                // - E0412 cannot find type `{}` in this scope
+                // - E0433 failed to resolve: use of undeclared type or module `{}`
+                //
+                // The first one is emitted for paths in type-position, and the
+                // latter one - for paths in expression-position.
+                //
+                // Thus (since we're in expression-position at this point), not to
+                // confuse the user, we want to keep the *message* from E0433 (so
+                // `parent_err`), but we want *hints* from E0412 (so `err`).
+                //
+                // And that's what happens below - we're just mixing both messages
+                // into a single one.
+                let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
+
+                // overwrite all properties with the parent's error message
+                err.messages = take(&mut parent_err.messages);
+                err.code = take(&mut parent_err.code);
+                swap(&mut err.span, &mut parent_err.span);
+                err.children = take(&mut parent_err.children);
+                err.sort_span = parent_err.sort_span;
+                err.is_lint = parent_err.is_lint.clone();
+
                 // merge the parent's suggestions with the typo suggestions
                 fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
                     match res1 {

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -6,7 +6,7 @@ use rustc_data_structures::unord::UnordSet;
 use rustc_errors::codes::*;
 use rustc_errors::{
     pluralize, struct_span_code_err, Applicability, Diag, ErrorGuaranteed, MultiSpan, StashKey,
-    StringPart,
+    StringPart, Suggestions,
 };
 use rustc_hir::def::Namespace;
 use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
@@ -2136,8 +2136,8 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             if let Some(span) = err.span.primary_span()
                 && let Some(mut diag) =
                     self.dcx().steal_non_err(span, StashKey::AssociatedTypeSuggestion)
-                && let Ok(ref mut s1) = err.suggestions
-                && let Ok(ref mut s2) = diag.suggestions
+                && let Suggestions::Enabled(ref mut s1) = err.suggestions
+                && let Suggestions::Enabled(ref mut s2) = diag.suggestions
             {
                 s1.append(s2);
                 diag.cancel()