macros: raw translation of subdiagnostics

Signed-off-by: David Wood <[email protected]>

compiler/rustc_ast_lowering/src/errors.rs

@@ -1,6 +1,4 @@
-use rustc_errors::{
-    codes::*, AddToDiagnostic, Diagnostic, DiagnosticArgFromDisplay, SubdiagnosticMessageOp,
-};
+use rustc_errors::{codes::*, AddToDiagnostic, DiagCtxt, Diagnostic, DiagnosticArgFromDisplay};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{symbol::Ident, Span, Symbol};
 
@@ -40,8 +38,8 @@ pub struct InvalidAbi {
 
 pub struct InvalidAbiReason(pub &'static str);
 
-impl AddToDiagnostic for InvalidAbiReason {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) {
+impl<'a> AddToDiagnostic<'a> for InvalidAbiReason {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut Diagnostic) {
         #[allow(rustc::untranslatable_diagnostic)]
         diag.note(self.0);
     }

compiler/rustc_ast_passes/src/errors.rs

@@ -1,7 +1,7 @@
 //! Errors emitted by ast_passes.
 
 use rustc_ast::ParamKindOrd;
-use rustc_errors::{codes::*, AddToDiagnostic, Applicability, Diagnostic, SubdiagnosticMessageOp};
+use rustc_errors::{codes::*, AddToDiagnostic, Applicability, DiagCtxt, Diagnostic};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{symbol::Ident, Span, Symbol};
 
@@ -371,8 +371,8 @@ pub struct ArgsBeforeConstraint {
 pub struct EmptyLabelManySpans(pub Vec<Span>);
 
 // The derive for `Vec<Span>` does multiple calls to `span_label`, adding commas between each
-impl AddToDiagnostic for EmptyLabelManySpans {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) {
+impl<'a> AddToDiagnostic<'a> for EmptyLabelManySpans {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut Diagnostic) {
         diag.span_labels(self.0, "");
     }
 }
@@ -728,8 +728,8 @@ pub struct StableFeature {
     pub since: Symbol,
 }
 
-impl AddToDiagnostic for StableFeature {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) {
+impl<'a> AddToDiagnostic<'a> for StableFeature {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut Diagnostic) {
         diag.arg("name", self.name);
         diag.arg("since", self.since);
         diag.help(fluent::ast_passes_stable_since);

compiler/rustc_builtin_macros/src/errors.rs

@@ -1,6 +1,6 @@
 use rustc_errors::{
     codes::*, AddToDiagnostic, DiagCtxt, Diagnostic, DiagnosticBuilder, EmissionGuarantee,
-    IntoDiagnostic, Level, MultiSpan, SingleLabelManySpans, SubdiagnosticMessageOp,
+    IntoDiagnostic, Level, MultiSpan, SingleLabelManySpans,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{symbol::Ident, Span, Symbol};
@@ -610,11 +610,14 @@ pub(crate) struct FormatUnusedArg {
 
 // Allow the singular form to be a subdiagnostic of the multiple-unused
 // form of diagnostic.
-impl AddToDiagnostic for FormatUnusedArg {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, f: F) {
+impl<'a> AddToDiagnostic<'a> for FormatUnusedArg {
+    fn add_to_diagnostic(self, dcx: &'a DiagCtxt, diag: &mut Diagnostic) {
         diag.arg("named", self.named);
-        let msg = f(diag, crate::fluent_generated::builtin_macros_format_unused_arg.into());
-        diag.span_label(self.span, msg);
+        let message = dcx.eagerly_translate(
+            crate::fluent_generated::builtin_macros_format_unused_arg,
+            diag.args(),
+        );
+        diag.span_label(self.span, message);
     }
 }
 

compiler/rustc_errors/src/diagnostic.rs

@@ -1,7 +1,7 @@
 use crate::snippet::Style;
 use crate::{
-    CodeSuggestion, DiagnosticBuilder, DiagnosticMessage, EmissionGuarantee, ErrCode, Level,
-    MultiSpan, SubdiagnosticMessage, Substitution, SubstitutionPart, SuggestionStyle,
+    CodeSuggestion, DiagCtxt, DiagnosticBuilder, DiagnosticMessage, EmissionGuarantee, ErrCode,
+    Level, MultiSpan, SubdiagnosticMessage, Substitution, SubstitutionPart, SuggestionStyle,
 };
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_error_messages::fluent_value_from_str_list_sep_by_and;
@@ -66,18 +66,12 @@ impl Into<FluentValue<'static>> for DiagnosticArgValue {
 /// Trait implemented by error types. This should not be implemented manually. Instead, use
 /// `#[derive(Subdiagnostic)]` -- see [rustc_macros::Subdiagnostic].
 #[rustc_diagnostic_item = "AddToDiagnostic"]
-pub trait AddToDiagnostic
+pub trait AddToDiagnostic<'a>
 where
     Self: Sized,
 {
     /// Add a subdiagnostic to an existing diagnostic.
-    fn add_to_diagnostic(self, diag: &mut Diagnostic) {
-        self.add_to_diagnostic_with(diag, |_, m| m);
-    }
-
-    /// Add a subdiagnostic to an existing diagnostic where `f` is invoked on every message used
-    /// (to optionally perform eager translation).
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, f: F);
+    fn add_to_diagnostic(self, dcx: &'a DiagCtxt, diag: &mut Diagnostic);
 }
 
 pub trait SubdiagnosticMessageOp =
@@ -855,16 +849,12 @@ impl Diagnostic {
     /// [rustc_macros::Subdiagnostic]). Performs eager translation of any translatable messages
     /// used in the subdiagnostic, so suitable for use with repeated messages (i.e. re-use of
     /// interpolated variables).
-    pub fn subdiagnostic(
+    pub fn subdiagnostic<'a>(
         &mut self,
-        dcx: &crate::DiagCtxt,
-        subdiagnostic: impl AddToDiagnostic,
+        dcx: &'a crate::DiagCtxt,
+        subdiagnostic: impl AddToDiagnostic<'a>,
     ) -> &mut Self {
-        subdiagnostic.add_to_diagnostic_with(self, |diag, msg| {
-            let args = diag.args();
-            let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
-            dcx.eagerly_translate(msg, args)
-        });
+        subdiagnostic.add_to_diagnostic(dcx, self);
         self
     }
 
@@ -911,7 +901,7 @@ impl Diagnostic {
     /// Helper function that takes a `SubdiagnosticMessage` and returns a `DiagnosticMessage` by
     /// combining it with the primary message of the diagnostic (if translatable, otherwise it just
     /// passes the user's string along).
-    pub(crate) fn subdiagnostic_message_to_diagnostic_message(
+    pub fn subdiagnostic_message_to_diagnostic_message(
         &self,
         attr: impl Into<SubdiagnosticMessage>,
     ) -> DiagnosticMessage {

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -403,10 +403,25 @@ impl<'a, G: EmissionGuarantee> DiagnosticBuilder<'a, G> {
     forward!((arg, with_arg)(
         name: impl Into<Cow<'static, str>>, arg: impl IntoDiagnosticArg,
     ));
-    forward!((subdiagnostic, with_subdiagnostic)(
-        dcx: &DiagCtxt,
-        subdiagnostic: impl crate::AddToDiagnostic,
-    ));
+
+    /// See [`Diagnostic::subdiagnostic()`].
+    pub fn subdiagnostic(
+        &mut self,
+        dcx: &'a DiagCtxt,
+        subdiagnostic: impl crate::AddToDiagnostic<'a>,
+    ) -> &mut Self {
+        self.diag.as_mut().unwrap().subdiagnostic(dcx, subdiagnostic);
+        self
+    }
+    /// See [`Diagnostic::subdiagnostic()`].
+    pub fn with_subdiagnostic(
+        mut self,
+        dcx: &'a DiagCtxt,
+        subdiagnostic: impl crate::AddToDiagnostic<'a>,
+    ) -> Self {
+        self.diag.as_mut().unwrap().subdiagnostic(dcx, subdiagnostic);
+        self
+    }
 }
 
 impl<G: EmissionGuarantee> Debug for DiagnosticBuilder<'_, G> {

compiler/rustc_errors/src/diagnostic_impls.rs

@@ -2,7 +2,7 @@ use crate::diagnostic::DiagnosticLocation;
 use crate::{fluent_generated as fluent, AddToDiagnostic};
 use crate::{
     DiagCtxt, DiagnosticArgValue, DiagnosticBuilder, EmissionGuarantee, ErrCode, IntoDiagnostic,
-    IntoDiagnosticArg, Level, SubdiagnosticMessageOp,
+    IntoDiagnosticArg, Level,
 };
 use rustc_ast as ast;
 use rustc_ast_pretty::pprust;
@@ -298,8 +298,8 @@ pub struct SingleLabelManySpans {
     pub spans: Vec<Span>,
     pub label: &'static str,
 }
-impl AddToDiagnostic for SingleLabelManySpans {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut crate::Diagnostic, _: F) {
+impl<'a> AddToDiagnostic<'a> for SingleLabelManySpans {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut crate::Diagnostic) {
         diag.span_labels(self.spans, self.label);
     }
 }

compiler/rustc_errors/src/lib.rs

@@ -1532,26 +1532,46 @@ impl DiagCtxtInner {
                 self.emit_diagnostic(Diagnostic::new(Note, note2));
             }
 
-            let mut bug =
-                if backtrace || self.ice_file.is_none() { bug.decorate(self) } else { bug.inner };
-
-            // "Undelay" the delayed bugs (into plain `Bug`s).
-            if bug.level != DelayedBug {
-                // NOTE(eddyb) not panicking here because we're already producing
-                // an ICE, and the more information the merrier.
-                let subdiag = InvalidFlushedDelayedDiagnosticLevel {
-                    span: bug.span.primary_span().unwrap(),
-                    level: bug.level,
-                };
-                // FIXME: Cannot use `Diagnostic::subdiagnostic` which takes `DiagCtxt`, but it
-                // just uses `DiagCtxtInner` functions.
-                subdiag.add_to_diagnostic_with(&mut bug, |diag, msg| {
-                    let args = diag.args();
-                    let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
-                    self.eagerly_translate(msg, args)
-                });
-            }
-            bug.level = Bug;
+            // This is a bit gnarly, but the `AddToDiagnostic` type uses a `DiagCtxt` to trigger
+            // translation. It could take an emitter or a `DiagCtxtInner` but it would make
+            // every other use of `AddToDiagnostic` more complex. This function is only invoked
+            // during the `Drop` of `DiagCtxtInner`, so we temporarily get a `T` from the `&mut T`
+            // here so we can put this back into a lock and back into a `DiagCtxt` to call the
+            // functions from `AddToDiagnostic`.
+            //
+            // FIXME(davidtwco): `AddToDiagnostic` should eventually be merged with
+            // `IntoDiagnostic`, and then the context determined by an associated type, depending
+            // on the needs of the specific diagnostic - once this is done, we can make these
+            // specific diagnostics take an emitter directly.
+            let bug = unsafe {
+                let old_dcx = std::ptr::read(self);
+                let (new_dcx, bug) = std::panic::catch_unwind(panic::AssertUnwindSafe(|| {
+                    let dcx = DiagCtxt { inner: Lock::new(old_dcx) };
+
+                    let mut bug = if backtrace || self.ice_file.is_none() {
+                        bug.decorate(&dcx)
+                    } else {
+                        bug.inner
+                    };
+
+                    // "Undelay" the delayed bugs (into plain `Bug`s).
+                    if bug.level != DelayedBug {
+                        // NOTE(eddyb) not panicking here because we're already producing
+                        // an ICE, and the more information the merrier.
+                        let subdiag = InvalidFlushedDelayedDiagnosticLevel {
+                            span: bug.span.primary_span().unwrap(),
+                            level: bug.level,
+                        };
+                        subdiag.add_to_diagnostic(&dcx, &mut bug);
+                    }
+                    bug.level = Bug;
+
+                    (dcx.inner.into_inner(), bug)
+                }))
+                .unwrap_or_else(|_| std::process::abort());
+                std::ptr::write(self, new_dcx);
+                bug
+            };
 
             self.emit_diagnostic(bug);
         }
@@ -1583,15 +1603,7 @@ impl DelayedDiagnostic {
         DelayedDiagnostic { inner: diagnostic, note: backtrace }
     }
 
-    fn decorate(mut self, dcx: &DiagCtxtInner) -> Diagnostic {
-        // FIXME: Cannot use `Diagnostic::subdiagnostic` which takes `DiagCtxt`, but it
-        // just uses `DiagCtxtInner` functions.
-        let subdiag_with = |diag: &mut Diagnostic, msg| {
-            let args = diag.args();
-            let msg = diag.subdiagnostic_message_to_diagnostic_message(msg);
-            dcx.eagerly_translate(msg, args)
-        };
-
+    fn decorate(mut self, dcx: &DiagCtxt) -> Diagnostic {
         match self.note.status() {
             BacktraceStatus::Captured => {
                 let inner = &self.inner;
@@ -1600,7 +1612,7 @@ impl DelayedDiagnostic {
                     emitted_at: inner.emitted_at.clone(),
                     note: self.note,
                 };
-                subdiag.add_to_diagnostic_with(&mut self.inner, subdiag_with);
+                subdiag.add_to_diagnostic(dcx, &mut self.inner);
             }
             // Avoid the needless newline when no backtrace has been captured,
             // the display impl should just be a single line.
@@ -1611,7 +1623,7 @@ impl DelayedDiagnostic {
                     emitted_at: inner.emitted_at.clone(),
                     note: self.note,
                 };
-                subdiag.add_to_diagnostic_with(&mut self.inner, subdiag_with);
+                subdiag.add_to_diagnostic(dcx, &mut self.inner);
             }
         }
 

compiler/rustc_hir_typeck/src/errors.rs

@@ -3,8 +3,8 @@ use std::borrow::Cow;
 
 use crate::fluent_generated as fluent;
 use rustc_errors::{
-    codes::*, AddToDiagnostic, Applicability, Diagnostic, DiagnosticArgValue, IntoDiagnosticArg,
-    MultiSpan, SubdiagnosticMessageOp,
+    codes::*, AddToDiagnostic, Applicability, DiagCtxt, Diagnostic, DiagnosticArgValue,
+    IntoDiagnosticArg, MultiSpan,
 };
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
 use rustc_middle::ty::Ty;
@@ -194,8 +194,8 @@ pub struct TypeMismatchFruTypo {
     pub expr: Option<String>,
 }
 
-impl AddToDiagnostic for TypeMismatchFruTypo {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) {
+impl<'a> AddToDiagnostic<'a> for TypeMismatchFruTypo {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut Diagnostic) {
         diag.arg("expr", self.expr.as_deref().unwrap_or("NONE"));
 
         // Only explain that `a ..b` is a range if it's split up
@@ -369,8 +369,8 @@ pub struct RemoveSemiForCoerce {
     pub semi: Span,
 }
 
-impl AddToDiagnostic for RemoveSemiForCoerce {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) {
+impl<'a> AddToDiagnostic<'a> for RemoveSemiForCoerce {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut Diagnostic) {
         let mut multispan: MultiSpan = self.semi.into();
         multispan.push_span_label(self.expr, fluent::hir_typeck_remove_semi_for_coerce_expr);
         multispan.push_span_label(self.ret, fluent::hir_typeck_remove_semi_for_coerce_ret);
@@ -541,18 +541,15 @@ pub enum CastUnknownPointerSub {
     From(Span),
 }
 
-impl AddToDiagnostic for CastUnknownPointerSub {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, f: F) {
+impl<'a> AddToDiagnostic<'a> for CastUnknownPointerSub {
+    fn add_to_diagnostic(self, _: &'a DiagCtxt, diag: &mut Diagnostic) {
         match self {
             CastUnknownPointerSub::To(span) => {
-                let msg = f(diag, crate::fluent_generated::hir_typeck_label_to);
-                diag.span_label(span, msg);
-                let msg = f(diag, crate::fluent_generated::hir_typeck_note);
-                diag.note(msg);
+                diag.span_label(span, crate::fluent_generated::hir_typeck_label_to);
+                diag.note(crate::fluent_generated::hir_typeck_note);
             }
             CastUnknownPointerSub::From(span) => {
-                let msg = f(diag, crate::fluent_generated::hir_typeck_label_from);
-                diag.span_label(span, msg);
+                diag.span_label(span, crate::fluent_generated::hir_typeck_label_from);
             }
         }
     }

compiler/rustc_hir_typeck/src/expr.rs

@@ -26,8 +26,8 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{
-    codes::*, pluralize, struct_span_code_err, AddToDiagnostic, Applicability, Diagnostic,
-    DiagnosticBuilder, ErrorGuaranteed, StashKey,
+    codes::*, pluralize, struct_span_code_err, Applicability, Diagnostic, DiagnosticBuilder,
+    ErrorGuaranteed, StashKey,
 };
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, DefKind, Res};
@@ -2611,7 +2611,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             // We know by construction that `<expr>.await` is either on Rust 2015
             // or results in `ExprKind::Await`. Suggest switching the edition to 2018.
             err.note("to `.await` a `Future`, switch to Rust 2018 or later");
-            HelpUseLatestEdition::new().add_to_diagnostic(&mut err);
+            err.subdiagnostic(self.dcx(), HelpUseLatestEdition::new());
         }
 
         err.emit()