Auto merge of #120576 - nnethercote:merge-Diagnostic-DiagnosticBuilder, r=davidtwco

Overhaul `Diagnostic` and `DiagnosticBuilder`

Implements the first part of https://github.com/rust-lang/compiler-team/issues/722, which moves functionality and use away from `Diagnostic`, onto `DiagnosticBuilder`.

Likely follow-ups:
- Move things around, because this PR was written to minimize diff size, so some things end up in sub-optimal places. E.g. `DiagnosticBuilder` has impls in both `diagnostic.rs` and `diagnostic_builder.rs`.
- Rename `Diagnostic` as `DiagInner` and `DiagnosticBuilder` as `Diag`.

r? `@davidtwco`

5 files changed, 20 insertions, 18 deletions

diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
index 674f7218ea6..fde67ac089a 100644
--- a/compiler/rustc_parse/src/errors.rs
+++ b/compiler/rustc_parse/src/errors.rs
@@ -3,7 +3,7 @@ use std::borrow::Cow;
 use rustc_ast::token::Token;
 use rustc_ast::{Path, Visibility};
 use rustc_errors::{
-    codes::*, AddToDiagnostic, Applicability, DiagCtxt, Diagnostic, DiagnosticBuilder,
+    codes::*, AddToDiagnostic, Applicability, DiagCtxt, DiagnosticBuilder, EmissionGuarantee,
     IntoDiagnostic, Level, SubdiagnosticMessageOp,
 };
 use rustc_macros::{Diagnostic, Subdiagnostic};
@@ -1475,7 +1475,11 @@ pub(crate) struct FnTraitMissingParen {
 }
 
 impl AddToDiagnostic for FnTraitMissingParen {
-    fn add_to_diagnostic_with<F: SubdiagnosticMessageOp>(self, diag: &mut Diagnostic, _: F) {
+    fn add_to_diagnostic_with<G: EmissionGuarantee, F: SubdiagnosticMessageOp<G>>(
+        self,
+        diag: &mut DiagnosticBuilder<'_, G>,
+        _: F,
+    ) {
         diag.span_label(self.span, crate::fluent_generated::parse_fn_trait_missing_paren);
         let applicability = if self.machine_applicable {
             Applicability::MachineApplicable
diff --git a/compiler/rustc_parse/src/lexer/diagnostics.rs b/compiler/rustc_parse/src/lexer/diagnostics.rs
index b1bd4ac75e5..52a029b20f6 100644
--- a/compiler/rustc_parse/src/lexer/diagnostics.rs
+++ b/compiler/rustc_parse/src/lexer/diagnostics.rs
@@ -1,6 +1,6 @@
 use super::UnmatchedDelim;
 use rustc_ast::token::Delimiter;
-use rustc_errors::Diagnostic;
+use rustc_errors::DiagnosticBuilder;
 use rustc_span::source_map::SourceMap;
 use rustc_span::Span;
 
@@ -31,7 +31,7 @@ pub fn same_indentation_level(sm: &SourceMap, open_sp: Span, close_sp: Span) ->
 // When we get a `)` or `]` for `{`, we should emit help message here
 // it's more friendly compared to report `unmatched error` in later phase
 pub fn report_missing_open_delim(
-    err: &mut Diagnostic,
+    err: &mut DiagnosticBuilder<'_>,
     unmatched_delims: &[UnmatchedDelim],
 ) -> bool {
     let mut reported_missing_open = false;
@@ -55,7 +55,7 @@ pub fn report_missing_open_delim(
 }
 
 pub fn report_suspicious_mismatch_block(
-    err: &mut Diagnostic,
+    err: &mut DiagnosticBuilder<'_>,
     diag_info: &TokenTreeDiagInfo,
     sm: &SourceMap,
     delim: Delimiter,
diff --git a/compiler/rustc_parse/src/parser/attr.rs b/compiler/rustc_parse/src/parser/attr.rs
index 98e062dd784..6545429b95b 100644
--- a/compiler/rustc_parse/src/parser/attr.rs
+++ b/compiler/rustc_parse/src/parser/attr.rs
@@ -8,7 +8,7 @@ use super::{AttrWrapper, Capturing, FnParseMode, ForceCollect, Parser, PathStyle
 use rustc_ast as ast;
 use rustc_ast::attr;
 use rustc_ast::token::{self, Delimiter, Nonterminal};
-use rustc_errors::{codes::*, Diagnostic, PResult};
+use rustc_errors::{codes::*, DiagnosticBuilder, PResult};
 use rustc_span::{sym, BytePos, Span};
 use thin_vec::ThinVec;
 use tracing::debug;
@@ -141,7 +141,7 @@ impl<'a> Parser<'a> {
 
     fn annotate_following_item_if_applicable(
         &self,
-        err: &mut Diagnostic,
+        err: &mut DiagnosticBuilder<'_>,
         span: Span,
         attr_type: OuterAttributeType,
     ) -> Option<Span> {
diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs
index 659716548d9..0cc2170714c 100644
--- a/compiler/rustc_parse/src/parser/diagnostics.rs
+++ b/compiler/rustc_parse/src/parser/diagnostics.rs
@@ -34,8 +34,8 @@ use rustc_ast::{
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{
-    pluralize, AddToDiagnostic, Applicability, DiagCtxt, Diagnostic, DiagnosticBuilder,
-    ErrorGuaranteed, FatalError, PErr, PResult,
+    pluralize, AddToDiagnostic, Applicability, DiagCtxt, DiagnosticBuilder, ErrorGuaranteed,
+    FatalError, PErr, PResult,
 };
 use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::Spanned;
@@ -208,11 +208,11 @@ struct MultiSugg {
 }
 
 impl MultiSugg {
-    fn emit(self, err: &mut Diagnostic) {
+    fn emit(self, err: &mut DiagnosticBuilder<'_>) {
         err.multipart_suggestion(self.msg, self.patches, self.applicability);
     }
 
-    fn emit_verbose(self, err: &mut Diagnostic) {
+    fn emit_verbose(self, err: &mut DiagnosticBuilder<'_>) {
         err.multipart_suggestion_verbose(self.msg, self.patches, self.applicability);
     }
 }
@@ -846,7 +846,7 @@ impl<'a> Parser<'a> {
         err.emit();
     }
 
-    fn check_too_many_raw_str_terminators(&mut self, err: &mut Diagnostic) -> bool {
+    fn check_too_many_raw_str_terminators(&mut self, err: &mut DiagnosticBuilder<'_>) -> bool {
         let sm = self.sess.source_map();
         match (&self.prev_token.kind, &self.token.kind) {
             (
@@ -2179,7 +2179,7 @@ impl<'a> Parser<'a> {
 
     pub(super) fn parameter_without_type(
         &mut self,
-        err: &mut Diagnostic,
+        err: &mut DiagnosticBuilder<'_>,
         pat: P<ast::Pat>,
         require_name: bool,
         first_param: bool,
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 20b9581f2ef..8826c06bebd 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -25,9 +25,7 @@ use rustc_ast::{Arm, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLim
 use rustc_ast::{ClosureBinder, MetaItemLit, StmtKind};
 use rustc_ast_pretty::pprust;
 use rustc_data_structures::stack::ensure_sufficient_stack;
-use rustc_errors::{
-    AddToDiagnostic, Applicability, Diagnostic, DiagnosticBuilder, PResult, StashKey,
-};
+use rustc_errors::{AddToDiagnostic, Applicability, DiagnosticBuilder, PResult, StashKey};
 use rustc_lexer::unescape::unescape_char;
 use rustc_macros::Subdiagnostic;
 use rustc_session::errors::{report_lit_error, ExprParenthesesNeeded};
@@ -865,7 +863,7 @@ impl<'a> Parser<'a> {
             );
             let mut err = self.dcx().struct_span_err(span, msg);
 
-            let suggest_parens = |err: &mut Diagnostic| {
+            let suggest_parens = |err: &mut DiagnosticBuilder<'_>| {
                 let suggestions = vec![
                     (span.shrink_to_lo(), "(".to_string()),
                     (span.shrink_to_hi(), ")".to_string()),
@@ -3437,7 +3435,7 @@ impl<'a> Parser<'a> {
         let mut recover_async = false;
         let in_if_guard = self.restrictions.contains(Restrictions::IN_IF_GUARD);
 
-        let mut async_block_err = |e: &mut Diagnostic, span: Span| {
+        let mut async_block_err = |e: &mut DiagnosticBuilder<'_>, span: Span| {
             recover_async = true;
             errors::AsyncBlockIn2015 { span }.add_to_diagnostic(e);
             errors::HelpUseLatestEdition::new().add_to_diagnostic(e);