Use a dedicated type instead of a reference for the diagnostic context

This paves the way for tracking more state (e.g. error tainting) in the diagnostic context handle

compiler/rustc_ast_lowering/src/lib.rs

@@ -50,7 +50,7 @@ use rustc_data_structures::fx::FxIndexSet;
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::sync::Lrc;
-use rustc_errors::{DiagArgFromDisplay, DiagCtxt, StashKey};
+use rustc_errors::{DiagArgFromDisplay, DiagCtxtHandle, StashKey};
 use rustc_hir::def::{DefKind, LifetimeRes, Namespace, PartialRes, PerNS, Res};
 use rustc_hir::def_id::{LocalDefId, LocalDefIdMap, CRATE_DEF_ID, LOCAL_CRATE};
 use rustc_hir::{self as hir};
@@ -188,7 +188,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
     }
 
-    pub(crate) fn dcx(&self) -> &'hir DiagCtxt {
+    pub(crate) fn dcx(&self) -> DiagCtxtHandle<'hir> {
         self.tcx.dcx()
     }
 }

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -12,6 +12,7 @@ use rustc_ast::visit::{walk_list, AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor}
 use rustc_ast::*;
 use rustc_ast_pretty::pprust::{self, State};
 use rustc_data_structures::fx::FxIndexMap;
+use rustc_errors::DiagCtxtHandle;
 use rustc_feature::Features;
 use rustc_parse::validate_attr;
 use rustc_session::lint::builtin::{
@@ -269,7 +270,7 @@ impl<'a> AstValidator<'a> {
         }
     }
 
-    fn dcx(&self) -> &rustc_errors::DiagCtxt {
+    fn dcx(&self) -> DiagCtxtHandle<'a> {
         self.session.dcx()
     }
 
@@ -809,11 +810,7 @@ impl<'a> AstValidator<'a> {
 
 /// Checks that generic parameters are in the correct order,
 /// which is lifetimes, then types and then consts. (`<'a, T, const N: usize>`)
-fn validate_generic_param_order(
-    dcx: &rustc_errors::DiagCtxt,
-    generics: &[GenericParam],
-    span: Span,
-) {
+fn validate_generic_param_order(dcx: DiagCtxtHandle<'_>, generics: &[GenericParam], span: Span) {
     let mut max_param: Option<ParamKindOrd> = None;
     let mut out_of_order = FxIndexMap::default();
     let mut param_idents = Vec::with_capacity(generics.len());

compiler/rustc_ast_passes/src/show_span.rs

@@ -8,6 +8,7 @@ use std::str::FromStr;
 use rustc_ast as ast;
 use rustc_ast::visit;
 use rustc_ast::visit::Visitor;
+use rustc_errors::DiagCtxtHandle;
 
 use crate::errors;
 
@@ -31,7 +32,7 @@ impl FromStr for Mode {
 }
 
 struct ShowSpanVisitor<'a> {
-    dcx: &'a rustc_errors::DiagCtxt,
+    dcx: DiagCtxtHandle<'a>,
     mode: Mode,
 }
 
@@ -58,7 +59,7 @@ impl<'a> Visitor<'a> for ShowSpanVisitor<'a> {
     }
 }
 
-pub fn run(dcx: &rustc_errors::DiagCtxt, mode: &str, krate: &ast::Crate) {
+pub fn run(dcx: DiagCtxtHandle<'_>, mode: &str, krate: &ast::Crate) {
     let Ok(mode) = mode.parse() else {
         return;
     };

compiler/rustc_attr/src/session_diagnostics.rs

@@ -1,7 +1,8 @@
 use std::num::IntErrorKind;
 
 use rustc_ast as ast;
-use rustc_errors::{codes::*, Applicability, Diag, DiagCtxt, Diagnostic, EmissionGuarantee, Level};
+use rustc_errors::DiagCtxtHandle;
+use rustc_errors::{codes::*, Applicability, Diag, Diagnostic, EmissionGuarantee, Level};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{Span, Symbol};
 
@@ -49,7 +50,7 @@ pub(crate) struct UnknownMetaItem<'a> {
 
 // Manual implementation to be able to format `expected` items correctly.
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for UnknownMetaItem<'_> {
-    fn into_diag(self, dcx: &'a DiagCtxt, level: Level) -> Diag<'a, G> {
+    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
         let expected = self.expected.iter().map(|name| format!("`{name}`")).collect::<Vec<_>>();
         Diag::new(dcx, level, fluent::attr_unknown_meta_item)
             .with_span(self.span)
@@ -202,7 +203,7 @@ pub(crate) struct UnsupportedLiteral {
 }
 
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for UnsupportedLiteral {
-    fn into_diag(self, dcx: &'a DiagCtxt, level: Level) -> Diag<'a, G> {
+    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
         let mut diag = Diag::new(
             dcx,
             level,

compiler/rustc_borrowck/src/borrowck_errors.rs

@@ -1,13 +1,13 @@
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
 
-use rustc_errors::{codes::*, struct_span_code_err, Diag, DiagCtxt};
+use rustc_errors::{codes::*, struct_span_code_err, Diag, DiagCtxtHandle};
 use rustc_middle::span_bug;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
 
 impl<'cx, 'tcx> crate::MirBorrowckCtxt<'cx, 'tcx> {
-    pub fn dcx(&self) -> &'tcx DiagCtxt {
+    pub fn dcx(&self) -> DiagCtxtHandle<'tcx> {
         self.infcx.dcx()
     }
 

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -4,8 +4,8 @@ use crate::session_diagnostics::{
     CaptureArgLabel, CaptureReasonLabel, CaptureReasonNote, CaptureReasonSuggest, CaptureVarCause,
     CaptureVarKind, CaptureVarPathUseCause, OnClosureNote,
 };
-use rustc_errors::{Applicability, Diag};
-use rustc_errors::{DiagCtxt, MultiSpan};
+use rustc_errors::MultiSpan;
+use rustc_errors::{Applicability, Diag, DiagCtxtHandle};
 use rustc_hir::def::{CtorKind, Namespace};
 use rustc_hir::CoroutineKind;
 use rustc_hir::{self as hir, LangItem};
@@ -593,7 +593,7 @@ impl UseSpans<'_> {
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub(super) fn args_subdiag(
         self,
-        dcx: &DiagCtxt,
+        dcx: DiagCtxtHandle<'_>,
         err: &mut Diag<'_>,
         f: impl FnOnce(Span) -> CaptureArgLabel,
     ) {
@@ -607,7 +607,7 @@ impl UseSpans<'_> {
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub(super) fn var_path_only_subdiag(
         self,
-        dcx: &DiagCtxt,
+        dcx: DiagCtxtHandle<'_>,
         err: &mut Diag<'_>,
         action: crate::InitializationRequiringAction,
     ) {
@@ -645,7 +645,7 @@ impl UseSpans<'_> {
     #[allow(rustc::diagnostic_outside_of_impl)]
     pub(super) fn var_subdiag(
         self,
-        dcx: &DiagCtxt,
+        dcx: DiagCtxtHandle<'_>,
         err: &mut Diag<'_>,
         kind: Option<rustc_middle::mir::BorrowKind>,
         f: impl FnOnce(hir::ClosureKind, Span) -> CaptureVarCause,

compiler/rustc_builtin_macros/src/errors.rs

@@ -1,5 +1,5 @@
 use rustc_errors::{
-    codes::*, Diag, DiagCtxt, Diagnostic, EmissionGuarantee, Level, MultiSpan,
+    codes::*, Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level, MultiSpan,
     SingleLabelManySpans, SubdiagMessageOp, Subdiagnostic,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
@@ -434,7 +434,7 @@ pub(crate) struct EnvNotDefinedWithUserMessage {
 // Hand-written implementation to support custom user messages.
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for EnvNotDefinedWithUserMessage {
     #[track_caller]
-    fn into_diag(self, dcx: &'a DiagCtxt, level: Level) -> Diag<'a, G> {
+    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
         #[expect(
             rustc::untranslatable_diagnostic,
             reason = "cannot translate user-provided messages"
@@ -801,7 +801,7 @@ pub(crate) struct AsmClobberNoReg {
 }
 
 impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for AsmClobberNoReg {
-    fn into_diag(self, dcx: &'a DiagCtxt, level: Level) -> Diag<'a, G> {
+    fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
         // eager translation as `span_labels` takes `AsRef<str>`
         let lbl1 = dcx.eagerly_translate_to_string(
             crate::fluent_generated::builtin_macros_asm_clobber_abi,

compiler/rustc_builtin_macros/src/proc_macro_harness.rs

@@ -3,6 +3,7 @@ use rustc_ast::ptr::P;
 use rustc_ast::visit::{self, Visitor};
 use rustc_ast::{self as ast, attr, NodeId};
 use rustc_ast_pretty::pprust;
+use rustc_errors::DiagCtxtHandle;
 use rustc_expand::base::{parse_macro_name_and_helper_attrs, ExtCtxt, ResolverExpand};
 use rustc_expand::expand::{AstFragment, ExpansionConfig};
 use rustc_feature::Features;
@@ -38,7 +39,7 @@ enum ProcMacro {
 struct CollectProcMacros<'a> {
     macros: Vec<ProcMacro>,
     in_root: bool,
-    dcx: &'a rustc_errors::DiagCtxt,
+    dcx: DiagCtxtHandle<'a>,
     source_map: &'a SourceMap,
     is_proc_macro_crate: bool,
     is_test_crate: bool,
@@ -52,7 +53,7 @@ pub fn inject(
     is_proc_macro_crate: bool,
     has_proc_macro_decls: bool,
     is_test_crate: bool,
-    dcx: &rustc_errors::DiagCtxt,
+    dcx: DiagCtxtHandle<'_>,
 ) {
     let ecfg = ExpansionConfig::default("proc_macro".to_string(), features);
     let mut cx = ExtCtxt::new(sess, ecfg, resolver, None);

compiler/rustc_builtin_macros/src/test_harness.rs

@@ -6,6 +6,7 @@ use rustc_ast::mut_visit::*;
 use rustc_ast::ptr::P;
 use rustc_ast::visit::{walk_item, Visitor};
 use rustc_ast::{attr, ModKind};
+use rustc_errors::DiagCtxtHandle;
 use rustc_expand::base::{ExtCtxt, ResolverExpand};
 use rustc_expand::expand::{AstFragment, ExpansionConfig};
 use rustc_feature::Features;
@@ -391,7 +392,7 @@ fn get_test_name(i: &ast::Item) -> Option<Symbol> {
     attr::first_attr_value_str_by_name(&i.attrs, sym::rustc_test_marker)
 }
 
-fn get_test_runner(dcx: &rustc_errors::DiagCtxt, krate: &ast::Crate) -> Option<ast::Path> {
+fn get_test_runner(dcx: DiagCtxtHandle<'_>, krate: &ast::Crate) -> Option<ast::Path> {
     let test_attr = attr::find_by_name(&krate.attrs, sym::test_runner)?;
     let meta_list = test_attr.meta_item_list()?;
     let span = test_attr.span;

compiler/rustc_codegen_cranelift/src/concurrency_limiter.rs

@@ -1,6 +1,7 @@
 use std::sync::{Arc, Condvar, Mutex};
 
 use jobserver::HelperThread;
+use rustc_errors::DiagCtxtHandle;
 use rustc_session::Session;
 
 // FIXME don't panic when a worker thread panics
@@ -46,7 +47,7 @@ impl ConcurrencyLimiter {
         }
     }
 
-    pub(super) fn acquire(&self, dcx: &rustc_errors::DiagCtxt) -> ConcurrencyLimiterToken {
+    pub(super) fn acquire(&self, dcx: DiagCtxtHandle<'_>) -> ConcurrencyLimiterToken {
         let mut state = self.state.lock().unwrap();
         loop {
             state.assert_invariants();

compiler/rustc_codegen_gcc/src/back/lto.rs

@@ -28,7 +28,7 @@ use rustc_codegen_ssa::back::write::{CodegenContext, FatLtoInput};
 use rustc_codegen_ssa::traits::*;
 use rustc_codegen_ssa::{looks_like_rust_object_file, ModuleCodegen, ModuleKind};
 use rustc_data_structures::memmap::Mmap;
-use rustc_errors::{DiagCtxt, FatalError};
+use rustc_errors::{DiagCtxtHandle, FatalError};
 use rustc_hir::def_id::LOCAL_CRATE;
 use rustc_middle::dep_graph::WorkProduct;
 use rustc_middle::middle::exported_symbols::{SymbolExportInfo, SymbolExportLevel};
@@ -59,7 +59,7 @@ struct LtoData {
 
 fn prepare_lto(
     cgcx: &CodegenContext<GccCodegenBackend>,
-    dcx: &DiagCtxt,
+    dcx: DiagCtxtHandle<'_>,
 ) -> Result<LtoData, FatalError> {
     let export_threshold = match cgcx.lto {
         // We're just doing LTO for our one crate
@@ -179,12 +179,13 @@ pub(crate) fn run_fat(
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
 ) -> Result<LtoModuleCodegen<GccCodegenBackend>, FatalError> {
     let dcx = cgcx.create_dcx();
-    let lto_data = prepare_lto(cgcx, &dcx)?;
+    let dcx = dcx.handle();
+    let lto_data = prepare_lto(cgcx, dcx)?;
     /*let symbols_below_threshold =
     lto_data.symbols_below_threshold.iter().map(|c| c.as_ptr()).collect::<Vec<_>>();*/
     fat_lto(
         cgcx,
-        &dcx,
+        dcx,
         modules,
         cached_modules,
         lto_data.upstream_modules,
@@ -195,7 +196,7 @@ pub(crate) fn run_fat(
 
 fn fat_lto(
     cgcx: &CodegenContext<GccCodegenBackend>,
-    _dcx: &DiagCtxt,
+    _dcx: DiagCtxtHandle<'_>,
     modules: Vec<FatLtoInput<GccCodegenBackend>>,
     cached_modules: Vec<(SerializedModule<ModuleBuffer>, WorkProduct)>,
     mut serialized_modules: Vec<(SerializedModule<ModuleBuffer>, CString)>,

compiler/rustc_codegen_gcc/src/back/write.rs

@@ -4,7 +4,7 @@ use gccjit::OutputKind;
 use rustc_codegen_ssa::back::link::ensure_removed;
 use rustc_codegen_ssa::back::write::{BitcodeSection, CodegenContext, EmitObj, ModuleConfig};
 use rustc_codegen_ssa::{CompiledModule, ModuleCodegen};
-use rustc_errors::DiagCtxt;
+use rustc_errors::DiagCtxtHandle;
 use rustc_fs_util::link_or_copy;
 use rustc_session::config::OutputType;
 use rustc_span::fatal_error::FatalError;
@@ -15,7 +15,7 @@ use crate::{GccCodegenBackend, GccContext};
 
 pub(crate) unsafe fn codegen(
     cgcx: &CodegenContext<GccCodegenBackend>,
-    dcx: &DiagCtxt,
+    dcx: DiagCtxtHandle<'_>,
     module: ModuleCodegen<GccContext>,
     config: &ModuleConfig,
 ) -> Result<CompiledModule, FatalError> {
@@ -166,7 +166,7 @@ pub(crate) unsafe fn codegen(
 
 pub(crate) fn link(
     _cgcx: &CodegenContext<GccCodegenBackend>,
-    _dcx: &DiagCtxt,
+    _dcx: DiagCtxtHandle<'_>,
     mut _modules: Vec<ModuleCodegen<GccContext>>,
 ) -> Result<ModuleCodegen<GccContext>, FatalError> {
     unimplemented!();

compiler/rustc_codegen_gcc/src/errors.rs

@@ -1,4 +1,4 @@
-use rustc_errors::{Diag, DiagCtxt, Diagnostic, EmissionGuarantee, Level};
+use rustc_errors::{Diag, DiagCtxtHandle, Diagnostic, EmissionGuarantee, Level};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::Span;
 
@@ -90,7 +90,7 @@ pub(crate) struct TargetFeatureDisableOrEnable<'a> {
 pub(crate) struct MissingFeatures;
 
 impl<G: EmissionGuarantee> Diagnostic<'_, G> for TargetFeatureDisableOrEnable<'_> {
-    fn into_diag(self, dcx: &'_ DiagCtxt, level: Level) -> Diag<'_, G> {
+    fn into_diag(self, dcx: DiagCtxtHandle<'_>, level: Level) -> Diag<'_, G> {
         let mut diag = Diag::new(dcx, level, fluent::codegen_gcc_target_feature_disable_or_enable);
         if let Some(span) = self.span {
             diag.span(span);

compiler/rustc_codegen_gcc/src/lib.rs

@@ -16,13 +16,7 @@
 #![allow(internal_features)]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
-#![feature(
-    rustc_private,
-    decl_macro,
-    never_type,
-    trusted_len,
-    hash_raw_entry
-)]
+#![feature(rustc_private, decl_macro, never_type, trusted_len, hash_raw_entry)]
 #![allow(broken_intra_doc_links)]
 #![recursion_limit = "256"]
 #![warn(rust_2018_idioms)]
@@ -104,7 +98,7 @@ use rustc_codegen_ssa::traits::{
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, ModuleCodegen};
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::sync::IntoDynSyncSend;
-use rustc_errors::{DiagCtxt, ErrorGuaranteed};
+use rustc_errors::{DiagCtxtHandle, ErrorGuaranteed};
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::ty::TyCtxt;
@@ -386,7 +380,7 @@ impl WriteBackendMethods for GccCodegenBackend {
 
     unsafe fn optimize(
         _cgcx: &CodegenContext<Self>,
-        _dcx: &DiagCtxt,
+        _dcx: DiagCtxtHandle<'_>,
         module: &ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
     ) -> Result<(), FatalError> {
@@ -411,14 +405,17 @@ impl WriteBackendMethods for GccCodegenBackend {
 
     unsafe fn codegen(
         cgcx: &CodegenContext<Self>,
-        dcx: &DiagCtxt,
+        dcx: DiagCtxtHandle<'_>,
         module: ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
     ) -> Result<CompiledModule, FatalError> {
         back::write::codegen(cgcx, dcx, module, config)
     }
 
-    fn prepare_thin(_module: ModuleCodegen<Self::Module>, _emit_summary: bool) -> (String, Self::ThinBuffer) {
+    fn prepare_thin(
+        _module: ModuleCodegen<Self::Module>,
+        _emit_summary: bool,
+    ) -> (String, Self::ThinBuffer) {
         unimplemented!();
     }
 
@@ -428,7 +425,7 @@ impl WriteBackendMethods for GccCodegenBackend {
 
     fn run_link(
         cgcx: &CodegenContext<Self>,
-        dcx: &DiagCtxt,
+        dcx: DiagCtxtHandle<'_>,
         modules: Vec<ModuleCodegen<Self::Module>>,
     ) -> Result<ModuleCodegen<Self::Module>, FatalError> {
         back::write::link(cgcx, dcx, modules)