Rename DiagnosticBuilder as Diag.

Much better!

Note that this involves renaming (and updating the value of)
`DIAGNOSTIC_BUILDER` in clippy.

compiler/rustc_hir_analysis/src/astconv/errors.rs

@@ -9,7 +9,7 @@ use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::unord::UnordMap;
 use rustc_errors::{
-    codes::*, pluralize, struct_span_code_err, Applicability, DiagnosticBuilder, ErrorGuaranteed,
+    codes::*, pluralize, struct_span_code_err, Applicability, Diag, ErrorGuaranteed,
 };
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
@@ -371,7 +371,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     // FIXME(fmease): Heavily adapted from `rustc_hir_typeck::method::suggest`. Deduplicate.
     fn note_ambiguous_inherent_assoc_type(
         &self,
-        err: &mut DiagnosticBuilder<'_>,
+        err: &mut Diag<'_>,
         candidates: Vec<DefId>,
         span: Span,
     ) {
@@ -429,7 +429,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let tcx = self.tcx();
 
         let adt_did = self_ty.ty_adt_def().map(|def| def.did());
-        let add_def_label = |err: &mut DiagnosticBuilder<'_>| {
+        let add_def_label = |err: &mut Diag<'_>| {
             if let Some(did) = adt_did {
                 err.span_label(
                     tcx.def_span(did),

compiler/rustc_hir_analysis/src/astconv/generics.rs

@@ -6,7 +6,7 @@ use crate::astconv::{
 use crate::structured_errors::{GenericArgsInfo, StructuredDiagnostic, WrongNumberOfGenericArgs};
 use rustc_ast::ast::ParamKindOrd;
 use rustc_errors::{
-    codes::*, struct_span_code_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, MultiSpan,
+    codes::*, struct_span_code_err, Applicability, Diag, ErrorGuaranteed, MultiSpan,
 };
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
@@ -47,7 +47,7 @@ fn generic_arg_mismatch_err(
         }
     }
 
-    let add_braces_suggestion = |arg: &GenericArg<'_>, err: &mut DiagnosticBuilder<'_>| {
+    let add_braces_suggestion = |arg: &GenericArg<'_>, err: &mut Diag<'_>| {
         let suggestions = vec![
             (arg.span().shrink_to_lo(), String::from("{ ")),
             (arg.span().shrink_to_hi(), String::from(" }")),

compiler/rustc_hir_analysis/src/astconv/lint.rs

@@ -1,5 +1,5 @@
 use rustc_ast::TraitObjectSyntax;
-use rustc_errors::{codes::*, DiagnosticBuilder, EmissionGuarantee, StashKey};
+use rustc_errors::{codes::*, Diag, EmissionGuarantee, StashKey};
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_lint_defs::{builtin::BARE_TRAIT_OBJECTS, Applicability};
@@ -13,7 +13,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     pub(super) fn maybe_lint_blanket_trait_impl<G: EmissionGuarantee>(
         &self,
         self_ty: &hir::Ty<'_>,
-        diag: &mut DiagnosticBuilder<'_, G>,
+        diag: &mut Diag<'_, G>,
     ) {
         let tcx = self.tcx();
         let parent_id = tcx.hir().get_parent_item(self_ty.hir_id).def_id;
@@ -75,11 +75,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     }
 
     /// Make sure that we are in the condition to suggest `impl Trait`.
-    fn maybe_lint_impl_trait(
-        &self,
-        self_ty: &hir::Ty<'_>,
-        diag: &mut DiagnosticBuilder<'_>,
-    ) -> bool {
+    fn maybe_lint_impl_trait(&self, self_ty: &hir::Ty<'_>, diag: &mut Diag<'_>) -> bool {
         let tcx = self.tcx();
         let parent_id = tcx.hir().get_parent_item(self_ty.hir_id).def_id;
         let (sig, generics, owner) = match tcx.hir_node_by_def_id(parent_id) {

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -18,8 +18,7 @@ use crate::require_c_abi_if_c_variadic;
 use rustc_ast::TraitObjectSyntax;
 use rustc_data_structures::fx::{FxHashSet, FxIndexMap};
 use rustc_errors::{
-    codes::*, struct_span_code_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, FatalError,
-    MultiSpan,
+    codes::*, struct_span_code_err, Applicability, Diag, ErrorGuaranteed, FatalError, MultiSpan,
 };
 use rustc_hir as hir;
 use rustc_hir::def::{CtorOf, DefKind, Namespace, Res};
@@ -1723,7 +1722,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
     pub fn prohibit_generics<'a>(
         &self,
         segments: impl Iterator<Item = &'a hir::PathSegment<'a>> + Clone,
-        extend: impl Fn(&mut DiagnosticBuilder<'_>),
+        extend: impl Fn(&mut Diag<'_>),
     ) -> bool {
         let args = segments.clone().flat_map(|segment| segment.args().args);
 
@@ -2739,7 +2738,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         &self,
         constrained_regions: FxHashSet<ty::BoundRegionKind>,
         referenced_regions: FxHashSet<ty::BoundRegionKind>,
-        generate_err: impl Fn(&str) -> DiagnosticBuilder<'tcx>,
+        generate_err: impl Fn(&str) -> Diag<'tcx>,
     ) {
         for br in referenced_regions.difference(&constrained_regions) {
             let br_name = match *br {