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

src/back/lto.rs

@@ -28,7 +28,7 @@
 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)>,

src/back/write.rs

@@ -4,7 +4,7 @@
 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 @@
 
 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!();

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);

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::{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 @@ fn print_statistics(&self) {
 
     unsafe fn optimize(
         _cgcx: &CodegenContext<Self>,
-        _dcx: &DiagCtxt,
+        _dcx: DiagCtxtHandle<'_>,
         module: &ModuleCodegen<Self::Module>,
         config: &ModuleConfig,
     ) -> Result<(), FatalError> {
@@ -411,14 +405,17 @@ unsafe fn optimize_thin(
 
     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 @@ fn serialize_module(_module: ModuleCodegen<Self::Module>) -> (String, Self::Modu
 
     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)