Overhaul Diagnostic args.

First, introduce a typedef `DiagnosticArgMap`.

Second, make the `args` field public, and remove the `args` getter and
`replace_args` setter. These were necessary previously because the getter
had a `#[allow(rustc::potential_query_instability)]` attribute, but that
was removed in rust-lang#120931 when the args were changed from `FxHashMap` to
`FxIndexMap`. (All the other `Diagnostic` fields are public.)

compiler/rustc_codegen_llvm/src/errors.rs

@@ -103,8 +103,7 @@ impl<G: EmissionGuarantee> IntoDiagnostic<'_, G> for ParseTargetMachineConfig<'_
     fn into_diagnostic(self, dcx: &'_ DiagCtxt, level: Level) -> DiagnosticBuilder<'_, G> {
         let diag: DiagnosticBuilder<'_, G> = self.0.into_diagnostic(dcx, level);
         let (message, _) = diag.messages.first().expect("`LlvmError` with no message");
-        let message = dcx.eagerly_translate_to_string(message.clone(), diag.args());
-
+        let message = dcx.eagerly_translate_to_string(message.clone(), diag.args.iter());
         DiagnosticBuilder::new(dcx, level, fluent::codegen_llvm_parse_target_machine_config)
             .with_arg("error", message)
     }

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -16,8 +16,8 @@ use rustc_data_structures::sync::Lrc;
 use rustc_errors::emitter::Emitter;
 use rustc_errors::translation::Translate;
 use rustc_errors::{
-    DiagCtxt, DiagnosticArgName, DiagnosticArgValue, DiagnosticBuilder, DiagnosticMessage, ErrCode,
-    FatalError, FluentBundle, Level, Style,
+    DiagCtxt, DiagnosticArgMap, DiagnosticBuilder, DiagnosticMessage, ErrCode, FatalError,
+    FluentBundle, Level, Style,
 };
 use rustc_fs_util::link_or_copy;
 use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
@@ -1001,7 +1001,7 @@ pub struct CguMessage;
 
 struct Diagnostic {
     msgs: Vec<(DiagnosticMessage, Style)>,
-    args: FxIndexMap<DiagnosticArgName, DiagnosticArgValue>,
+    args: DiagnosticArgMap,
     code: Option<ErrCode>,
     lvl: Level,
 }
@@ -1813,8 +1813,8 @@ impl Translate for SharedEmitter {
 
 impl Emitter for SharedEmitter {
     fn emit_diagnostic(&mut self, diag: rustc_errors::Diagnostic) {
-        let args: FxIndexMap<DiagnosticArgName, DiagnosticArgValue> =
-            diag.args().map(|(name, arg)| (name.clone(), arg.clone())).collect();
+        let args: DiagnosticArgMap =
+            diag.args.iter().map(|(name, arg)| (name.clone(), arg.clone())).collect();
         drop(self.sender.send(SharedEmitterMessage::Diagnostic(Diagnostic {
             msgs: diag.messages.clone(),
             args: args.clone(),
@@ -1857,7 +1857,7 @@ impl SharedEmitterMain {
                     let dcx = sess.dcx();
                     let mut d = rustc_errors::Diagnostic::new_with_messages(diag.lvl, diag.msgs);
                     d.code = diag.code; // may be `None`, that's ok
-                    d.replace_args(diag.args);
+                    d.args = diag.args;
                     dcx.emit_diagnostic(d);
                 }
                 Ok(SharedEmitterMessage::InlineAsmError(cookie, msg, level, source)) => {

compiler/rustc_const_eval/src/errors.rs

@@ -437,7 +437,7 @@ pub trait ReportErrorExt {
             let mut diag = dcx.struct_allow(DiagnosticMessage::Str(String::new().into()));
             let message = self.diagnostic_message();
             self.add_args(&mut diag);
-            let s = dcx.eagerly_translate_to_string(message, diag.args());
+            let s = dcx.eagerly_translate_to_string(message, diag.args.iter());
             diag.cancel();
             s
         })
@@ -864,7 +864,7 @@ impl<'tcx> ReportErrorExt for InvalidProgramInfo<'tcx> {
                 let dummy_level = Level::Bug;
                 let dummy_diag: DiagnosticBuilder<'_, ()> =
                     e.into_diagnostic().into_diagnostic(diag.dcx, dummy_level);
-                for (name, val) in dummy_diag.args() {
+                for (name, val) in dummy_diag.args.iter() {
                     diag.arg(name.clone(), val.clone());
                 }
                 dummy_diag.cancel();

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -446,7 +446,7 @@ pub fn format_interp_error<'tcx>(dcx: &DiagCtxt, e: InterpErrorInfo<'tcx>) -> St
     let mut diag = dcx.struct_allow("");
     let msg = e.diagnostic_message();
     e.add_args(&mut diag);
-    let s = dcx.eagerly_translate_to_string(msg, diag.args());
+    let s = dcx.eagerly_translate_to_string(msg, diag.args.iter());
     diag.cancel();
     s
 }

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -45,7 +45,7 @@ impl Translate for AnnotateSnippetEmitter {
 impl Emitter for AnnotateSnippetEmitter {
     /// The entry point for the diagnostics generation
     fn emit_diagnostic(&mut self, mut diag: Diagnostic) {
-        let fluent_args = to_fluent_args(diag.args());
+        let fluent_args = to_fluent_args(diag.args.iter());
 
         let mut suggestions = diag.suggestions.unwrap_or(vec![]);
         self.primary_span_formatted(&mut diag.span, &mut suggestions, &fluent_args);

compiler/rustc_errors/src/diagnostic.rs

@@ -98,6 +98,8 @@ pub trait DecorateLint<'a, G: EmissionGuarantee> {
     fn msg(&self) -> DiagnosticMessage;
 }
 
+pub type DiagnosticArgMap = FxIndexMap<DiagnosticArgName, DiagnosticArgValue>;
+
 /// The main part of a diagnostic. Note that `DiagnosticBuilder`, which wraps
 /// this type, is used for most operations, and should be used instead whenever
 /// possible. This type should only be used when `DiagnosticBuilder`'s lifetime
@@ -114,7 +116,7 @@ pub struct Diagnostic {
     pub span: MultiSpan,
     pub children: Vec<SubDiagnostic>,
     pub suggestions: Result<Vec<CodeSuggestion>, SuggestionsDisabled>,
-    args: FxIndexMap<DiagnosticArgName, DiagnosticArgValue>,
+    pub args: DiagnosticArgMap,
 
     /// 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
@@ -328,14 +330,6 @@ impl Diagnostic {
     pub(crate) fn arg(&mut self, name: impl Into<DiagnosticArgName>, arg: impl IntoDiagnosticArg) {
         self.args.insert(name.into(), arg.into_diagnostic_arg());
     }
-
-    pub fn args(&self) -> impl Iterator<Item = DiagnosticArg<'_>> {
-        self.args.iter()
-    }
-
-    pub fn replace_args(&mut self, args: FxIndexMap<DiagnosticArgName, DiagnosticArgValue>) {
-        self.args = args;
-    }
 }
 
 /// `DiagnosticBuilder` impls many `&mut self -> &mut Self` methods. Each one
@@ -965,7 +959,7 @@ impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
         subdiagnostic: impl AddToDiagnostic,
     ) -> &mut Self {
         subdiagnostic.add_to_diagnostic_with(self, |diag, msg| {
-            let args = diag.args();
+            let args = diag.args.iter();
             let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
             dcx.eagerly_translate(msg, args)
         });
@@ -1043,7 +1037,7 @@ impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
 }
 
 impl Diagnostic {
-    /// Fields used for Hash, and PartialEq trait
+    /// Fields used for Hash, and PartialEq trait.
     fn keys(
         &self,
     ) -> (
@@ -1063,7 +1057,7 @@ impl Diagnostic {
             &self.span,
             &self.children,
             &self.suggestions,
-            self.args().collect(),
+            self.args.iter().collect(),
             // omit self.sort_span
             &self.is_lint,
             // omit self.emitted_at

compiler/rustc_errors/src/emitter.rs

@@ -519,7 +519,7 @@ impl Emitter for HumanEmitter {
     }
 
     fn emit_diagnostic(&mut self, mut diag: Diagnostic) {
-        let fluent_args = to_fluent_args(diag.args());
+        let fluent_args = to_fluent_args(diag.args.iter());
 
         let mut suggestions = diag.suggestions.unwrap_or(vec![]);
         self.primary_span_formatted(&mut diag.span, &mut suggestions, &fluent_args);

compiler/rustc_errors/src/json.rs

@@ -341,7 +341,7 @@ struct UnusedExterns<'a, 'b, 'c> {
 
 impl Diagnostic {
     fn from_errors_diagnostic(diag: crate::Diagnostic, je: &JsonEmitter) -> Diagnostic {
-        let args = to_fluent_args(diag.args());
+        let args = to_fluent_args(diag.args.iter());
         let sugg = diag.suggestions.iter().flatten().map(|sugg| {
             let translated_message =
                 je.translate_message(&sugg.msg, &args).map_err(Report::new).unwrap();

compiler/rustc_errors/src/lib.rs

@@ -37,7 +37,7 @@ extern crate self as rustc_errors;
 
 pub use codes::*;
 pub use diagnostic::{
-    AddToDiagnostic, DecorateLint, Diagnostic, DiagnosticArg, DiagnosticArgName,
+    AddToDiagnostic, DecorateLint, Diagnostic, DiagnosticArg, DiagnosticArgMap, DiagnosticArgName,
     DiagnosticArgValue, DiagnosticStyledString, IntoDiagnosticArg, StringPart, SubDiagnostic,
     SubdiagnosticMessageOp,
 };
@@ -1486,9 +1486,8 @@ impl DiagCtxtInner {
         diag: &Diagnostic,
         msg: impl Into<SubdiagnosticMessage>,
     ) -> SubdiagnosticMessage {
-        let args = diag.args();
         let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
-        self.eagerly_translate(msg, args)
+        self.eagerly_translate(msg, diag.args.iter())
     }
 
     fn flush_delayed(&mut self) {

src/librustdoc/passes/lint/check_code_block_syntax.rs

@@ -159,7 +159,7 @@ impl Emitter for BufferEmitter {
     fn emit_diagnostic(&mut self, diag: Diagnostic) {
         let mut buffer = self.buffer.borrow_mut();
 
-        let fluent_args = to_fluent_args(diag.args());
+        let fluent_args = to_fluent_args(diag.args.iter());
         let translated_main_message = self
             .translate_message(&diag.messages[0].0, &fluent_args)
             .unwrap_or_else(|e| panic!("{e}"));