Rollup merge of rust-lang#142724 - xizheyin:avoid_overwrite_args, r=oli-obk

Add runtime check to avoid overwrite arg in `Diag`

## Origin PR description
At first, I set up a `debug_assert` check for the arg method to make sure that `args` in `Diag` aren't easily overwritten, and I added the `remove_arg()` method, so that if you do need to overwrite an arg, then you can explicitly call `remove_arg()` to remove it first, then call `arg()` to overwrite it.

For the code before the rust-lang#142015 change, it won't compile because it will report an error
```
arg `instance`already exists.
```

This PR also modifies all diagnostics that fail the check to pass the check. There are two cases of check failure:

1. ~~Between *the parent diagnostic and the subdiagnostic*, or *between the subdiagnostics* have the same field between them. In this case, I renamed the conflicting fields.~~
2. ~~For subdiagnostics stored in `Vec`, the rendering may iteratively write the same arg over and over again. In this case, I changed the auto-generation with `derive(SubDiagnostic)` to manually implementing `SubDiagnostic` and manually rendered it with `eagerly_translate()`, similar to rust-lang#142031 (comment), and after rendering it I manually deleted useless arg with the newly added `remove_arg` method.~~

## Final Decision

After trying and discussing, we made a final decision.

For `#[derive(Subdiagnostic)]`, This PR made two changes:

1. After the subdiagnostic is rendered, remove all args of this subdiagnostic, which allows for usage like `Vec<Subdiag>`.
2. Store `diag.args` before setting arguments, so that you can restore the contents of the main diagnostic after deleting the arguments after subdiagnostic is rendered, to avoid deleting the main diagnostic's arg when they have the same name args.

Author: jdonszelmann

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -1284,8 +1284,14 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                         && !spans.is_empty()
                     {
                         let mut span: MultiSpan = spans.clone().into();
+                        err.arg("ty", param_ty.to_string());
+                        let msg = err.dcx.eagerly_translate_to_string(
+                            fluent::borrowck_moved_a_fn_once_in_call_def,
+                            err.args.iter(),
+                        );
+                        err.remove_arg("ty");
                         for sp in spans {
-                            span.push_span_label(sp, fluent::borrowck_moved_a_fn_once_in_call_def);
+                            span.push_span_label(sp, msg.clone());
                         }
                         span.push_span_label(
                             fn_call_span,

compiler/rustc_builtin_macros/src/errors.rs

@@ -660,6 +660,7 @@ impl Subdiagnostic for FormatUnusedArg {
     fn add_to_diag<G: EmissionGuarantee>(self, diag: &mut Diag<'_, G>) {
         diag.arg("named", self.named);
         let msg = diag.eagerly_translate(crate::fluent_generated::builtin_macros_format_unused_arg);
+        diag.remove_arg("named");
         diag.span_label(self.span, msg);
     }
 }

compiler/rustc_const_eval/src/errors.rs

@@ -291,6 +291,9 @@ impl Subdiagnostic for FrameNote {
             span.push_span_label(self.span, fluent::const_eval_frame_note_last);
         }
         let msg = diag.eagerly_translate(fluent::const_eval_frame_note);
+        diag.remove_arg("times");
+        diag.remove_arg("where_");
+        diag.remove_arg("instance");
         diag.span_note(span, msg);
     }
 }

compiler/rustc_errors/src/diagnostic.rs

@@ -289,6 +289,9 @@ pub struct DiagInner {
     pub suggestions: Suggestions,
     pub args: DiagArgMap,
 
+    // This is used to store args and restore them after a subdiagnostic is rendered.
+    pub reserved_args: DiagArgMap,
+
     /// This is not used for highlighting or rendering any error message. Rather, it can be used
     /// as a sort key to sort a buffer of diagnostics. By default, it is the primary span of
     /// `span` if there is one. Otherwise, it is `DUMMY_SP`.
@@ -319,6 +322,7 @@ impl DiagInner {
             children: vec![],
             suggestions: Suggestions::Enabled(vec![]),
             args: Default::default(),
+            reserved_args: Default::default(),
             sort_span: DUMMY_SP,
             is_lint: None,
             long_ty_path: None,
@@ -390,7 +394,27 @@ impl DiagInner {
     }
 
     pub(crate) fn arg(&mut self, name: impl Into<DiagArgName>, arg: impl IntoDiagArg) {
-        self.args.insert(name.into(), arg.into_diag_arg(&mut self.long_ty_path));
+        let name = name.into();
+        let value = arg.into_diag_arg(&mut self.long_ty_path);
+        // This assertion is to avoid subdiagnostics overwriting an existing diagnostic arg.
+        debug_assert!(
+            !self.args.contains_key(&name) || self.args.get(&name) == Some(&value),
+            "arg {} already exists",
+            name
+        );
+        self.args.insert(name, value);
+    }
+
+    pub fn remove_arg(&mut self, name: &str) {
+        self.args.swap_remove(name);
+    }
+
+    pub fn store_args(&mut self) {
+        self.reserved_args = self.args.clone();
+    }
+
+    pub fn restore_args(&mut self) {
+        self.args = std::mem::take(&mut self.reserved_args);
     }
 
     /// Fields used for Hash, and PartialEq trait.
@@ -1423,6 +1447,12 @@ impl<'a, G: EmissionGuarantee> Diag<'a, G> {
         self.downgrade_to_delayed_bug();
         self.emit()
     }
+
+    pub fn remove_arg(&mut self, name: &str) {
+        if let Some(diag) = self.diag.as_mut() {
+            diag.remove_arg(name);
+        }
+    }
 }
 
 /// Destructor bomb: every `Diag` must be consumed (emitted, cancelled, etc.)

compiler/rustc_hir_analysis/src/errors.rs

@@ -127,6 +127,7 @@ pub(crate) enum AssocItemNotFoundSugg<'a> {
     SimilarInOtherTrait {
         #[primary_span]
         span: Span,
+        trait_name: &'a str,
         assoc_kind: &'static str,
         suggested_name: Symbol,
     },

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -309,6 +309,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                         // change the associated item.
                         err.sugg = Some(errors::AssocItemNotFoundSugg::SimilarInOtherTrait {
                             span: assoc_ident.span,
+                            trait_name: &trait_name,
                             assoc_kind: assoc_kind_str,
                             suggested_name,
                         });

compiler/rustc_lint/src/levels.rs

@@ -482,7 +482,8 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                     let name = lint_name.as_str();
                     let suggestion = RenamedLintSuggestion::WithoutSpan { replace };
                     let requested_level = RequestedLevel { level, lint_name };
-                    let lint = RenamedLintFromCommandLine { name, suggestion, requested_level };
+                    let lint =
+                        RenamedLintFromCommandLine { name, replace, suggestion, requested_level };
                     self.emit_lint(RENAMED_AND_REMOVED_LINTS, lint);
                 }
                 CheckLintNameResult::Removed(ref reason) => {
@@ -824,7 +825,7 @@ impl<'s, P: LintLevelsProvider> LintLevelsBuilder<'s, P> {
                                 RenamedLintSuggestion::WithSpan { suggestion: sp, replace };
                             let name =
                                 tool_ident.map(|tool| format!("{tool}::{name}")).unwrap_or(name);
-                            let lint = RenamedLint { name: name.as_str(), suggestion };
+                            let lint = RenamedLint { name: name.as_str(), replace, suggestion };
                             self.emit_span_lint(RENAMED_AND_REMOVED_LINTS, sp.into(), lint);
                         }
 

compiler/rustc_lint/src/lifetime_syntax.rs

@@ -422,12 +422,12 @@ fn build_mismatch_suggestion(
     lifetime_name: &str,
     infos: &[&Info<'_>],
 ) -> lints::MismatchedLifetimeSyntaxesSuggestion {
-    let lifetime_name = lifetime_name.to_owned();
+    let lifetime_name_sugg = lifetime_name.to_owned();
 
     let suggestions = infos.iter().map(|info| info.suggestion(&lifetime_name)).collect();
 
     lints::MismatchedLifetimeSyntaxesSuggestion::Explicit {
-        lifetime_name,
+        lifetime_name_sugg,
         suggestions,
         tool_only: false,
     }

compiler/rustc_lint/src/lints.rs

@@ -1089,6 +1089,7 @@ pub(crate) struct DeprecatedLintNameFromCommandLine<'a> {
 #[diag(lint_renamed_lint)]
 pub(crate) struct RenamedLint<'a> {
     pub name: &'a str,
+    pub replace: &'a str,
     #[subdiagnostic]
     pub suggestion: RenamedLintSuggestion<'a>,
 }
@@ -1109,6 +1110,7 @@ pub(crate) enum RenamedLintSuggestion<'a> {
 #[diag(lint_renamed_lint)]
 pub(crate) struct RenamedLintFromCommandLine<'a> {
     pub name: &'a str,
+    pub replace: &'a str,
     #[subdiagnostic]
     pub suggestion: RenamedLintSuggestion<'a>,
     #[subdiagnostic]
@@ -3244,7 +3246,7 @@ pub(crate) enum MismatchedLifetimeSyntaxesSuggestion {
     },
 
     Explicit {
-        lifetime_name: String,
+        lifetime_name_sugg: String,
         suggestions: Vec<(Span, String)>,
         tool_only: bool,
     },
@@ -3298,13 +3300,12 @@ impl Subdiagnostic for MismatchedLifetimeSyntaxesSuggestion {
                 );
             }
 
-            Explicit { lifetime_name, suggestions, tool_only } => {
-                diag.arg("lifetime_name", lifetime_name);
-
+            Explicit { lifetime_name_sugg, suggestions, tool_only } => {
+                diag.arg("lifetime_name_sugg", lifetime_name_sugg);
                 let msg = diag.eagerly_translate(
                     fluent::lint_mismatched_lifetime_syntaxes_suggestion_explicit,
                 );
-
+                diag.remove_arg("lifetime_name_sugg");
                 diag.multipart_suggestion_with_style(
                     msg,
                     suggestions,

compiler/rustc_macros/src/diagnostics/subdiagnostic.rs

@@ -220,7 +220,7 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
     }
 
     /// Generates the code for a field with no attributes.
-    fn generate_field_arg(&mut self, binding_info: &BindingInfo<'_>) -> TokenStream {
+    fn generate_field_arg(&mut self, binding_info: &BindingInfo<'_>) -> (TokenStream, TokenStream) {
         let diag = &self.parent.diag;
 
         let field = binding_info.ast();
@@ -230,12 +230,16 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
         let ident = field.ident.as_ref().unwrap();
         let ident = format_ident!("{}", ident); // strip `r#` prefix, if present
 
-        quote! {
+        let args = quote! {
             #diag.arg(
                 stringify!(#ident),
                 #field_binding
             );
-        }
+        };
+        let remove_args = quote! {
+            #diag.remove_arg(stringify!(#ident));
+        };
+        (args, remove_args)
     }
 
     /// Generates the necessary code for all attributes on a field.
@@ -600,8 +604,13 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
 
             calls.extend(call);
         }
-
-        let plain_args: TokenStream = self
+        let store_args = quote! {
+            #diag.store_args();
+        };
+        let restore_args = quote! {
+            #diag.restore_args();
+        };
+        let (plain_args, remove_args): (TokenStream, TokenStream) = self
             .variant
             .bindings()
             .iter()
@@ -610,12 +619,23 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
             .collect();
 
         let formatting_init = &self.formatting_init;
+
+        // For #[derive(Subdiagnostic)]
+        //
+        // - Store args of the main diagnostic for later restore.
+        // - add args of subdiagnostic.
+        // - Generate the calls, such as note, label, etc.
+        // - Remove the arguments for allowing Vec<Subdiagnostic> to be used.
+        // - Restore the arguments for allowing main and subdiagnostic share the same fields.
         Ok(quote! {
             #init
             #formatting_init
             #attr_args
+            #store_args
             #plain_args
             #calls
+            #remove_args
+            #restore_args
         })
     }
 }