Auto merge of #119146 - nnethercote:rm-DiagCtxt-api-duplication, r=compiler-errors

Remove `DiagCtxt` API duplication

`DiagCtxt` defines the internal API for creating and emitting diagnostics: methods like `struct_err`, `struct_span_warn`, `note`, `create_fatal`, `emit_bug`. There are over 50 methods.

Some of these methods are then duplicated across several other types: `Session`, `ParseSess`, `Parser`, `ExtCtxt`, and `MirBorrowckCtxt`. `Session` duplicates the most, though half the ones it does are unused. Each duplicated method just calls forward to the corresponding method in `DiagCtxt`. So this duplication exists to (in the best case) shorten chains like `ecx.tcx.sess.parse_sess.dcx.emit_err()` to `ecx.emit_err()`.

This API duplication is ugly and has been bugging me for a while. And it's inconsistent: there's no real logic about which methods are duplicated, and the use of `#[rustc_lint_diagnostic]` and `#[track_caller]` attributes vary across the duplicates.

This PR removes the duplicated API methods and makes all diagnostic creation and emission go through `DiagCtxt`. It also adds `dcx` getter methods to several types to shorten chains. This approach scales *much* better than API duplication; indeed, the PR adds `dcx()` to numerous types that didn't have API duplication: `TyCtxt`, `LoweringCtxt`, `ConstCx`, `FnCtxt`, `TypeErrCtxt`, `InferCtxt`, `CrateLoader`, `CheckAttrVisitor`, and `Resolver`. These result in a lot of changes from `foo.tcx.sess.emit_err()` to `foo.dcx().emit_err()`. (You could do this with more types, but it gets into diminishing returns territory for types that don't emit many diagnostics.)

After all these changes, some call sites are more verbose, some are less verbose, and many are the same. The total number of lines is reduced, mostly because of the removed API duplication. And consistency is increased, because calls to `emit_err` and friends are always preceded with `.dcx()` or `.dcx`.

r? `@compiler-errors`

9 files changed, 14 insertions, 14 deletions

diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 75f9560f526..1a25d3f7993 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -2996,7 +2996,7 @@ fn clean_use_statement_inner<'tcx>(
 
     if pub_underscore && let Some(ref inline) = inline_attr {
         rustc_errors::struct_span_err!(
-            cx.tcx.sess,
+            cx.tcx.dcx(),
             inline.span(),
             E0780,
             "anonymous imports cannot be inlined"
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 150625c6d92..179f37e6d96 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1012,7 +1012,7 @@ pub(crate) trait AttributesExt {
                             match Cfg::parse(cfg_mi) {
                                 Ok(new_cfg) => cfg &= new_cfg,
                                 Err(e) => {
-                                    sess.span_err(e.span, e.msg);
+                                    sess.dcx().span_err(e.span, e.msg);
                                 }
                             }
                         }
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 4e904ffd768..102a9f40e9b 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -326,7 +326,7 @@ pub(crate) fn run_global_ctxt(
         tcx.hir().for_each_module(|module| tcx.ensure().check_mod_item_types(module))
     });
 
-    tcx.sess.abort_if_errors();
+    tcx.dcx().abort_if_errors();
     tcx.sess.time("missing_docs", || rustc_lint::check_crate(tcx));
     tcx.sess.time("check_mod_attrs", || {
         tcx.hir().for_each_module(|module| tcx.ensure().check_mod_attrs(module))
@@ -447,7 +447,7 @@ pub(crate) fn run_global_ctxt(
 
     tcx.sess.time("check_lint_expectations", || tcx.check_expectations(Some(sym::rustdoc)));
 
-    if tcx.sess.dcx().has_errors_or_lint_errors().is_some() {
+    if tcx.dcx().has_errors_or_lint_errors().is_some() {
         rustc_errors::FatalError.raise();
     }
 
@@ -494,7 +494,7 @@ impl<'tcx> Visitor<'tcx> for EmitIgnoredResolutionErrors<'tcx> {
                     .collect::<String>()
             );
             let mut err = rustc_errors::struct_span_err!(
-                self.tcx.sess,
+                self.tcx.dcx(),
                 path.span,
                 E0433,
                 "failed to resolve: {label}",
diff --git a/src/librustdoc/html/render/context.rs b/src/librustdoc/html/render/context.rs
index f0199703c4e..aad63f8578a 100644
--- a/src/librustdoc/html/render/context.rs
+++ b/src/librustdoc/html/render/context.rs
@@ -758,7 +758,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         // Flush pending errors.
         Rc::get_mut(&mut self.shared).unwrap().fs.close();
         let nb_errors =
-            self.shared.errors.iter().map(|err| self.tcx().sess.struct_err(err).emit()).count();
+            self.shared.errors.iter().map(|err| self.tcx().dcx().struct_err(err).emit()).count();
         if nb_errors > 0 {
             Err(Error::new(io::Error::new(io::ErrorKind::Other, "I/O error"), ""))
         } else {
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index 34350c2ed3a..118c6eeb289 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2362,7 +2362,7 @@ fn render_call_locations<W: fmt::Write>(mut w: W, cx: &mut Context<'_>, item: &c
             Ok(contents) => contents,
             Err(err) => {
                 let span = item.span(tcx).map_or(rustc_span::DUMMY_SP, |span| span.inner());
-                tcx.sess.span_err(span, format!("failed to read file {}: {err}", path.display()));
+                tcx.dcx().span_err(span, format!("failed to read file {}: {err}", path.display()));
                 return false;
             }
         };
diff --git a/src/librustdoc/html/sources.rs b/src/librustdoc/html/sources.rs
index e160ec12f52..d4b1da71b40 100644
--- a/src/librustdoc/html/sources.rs
+++ b/src/librustdoc/html/sources.rs
@@ -146,7 +146,7 @@ impl DocVisitor for SourceCollector<'_, '_> {
             self.cx.include_sources = match self.emit_source(&filename, file_span) {
                 Ok(()) => true,
                 Err(e) => {
-                    self.cx.shared.tcx.sess.span_err(
+                    self.cx.shared.tcx.dcx().span_err(
                         span,
                         format!(
                             "failed to render source code for `{filename}`: {e}",
diff --git a/src/librustdoc/lib.rs b/src/librustdoc/lib.rs
index 19db429ad8a..ad1838c53ad 100644
--- a/src/librustdoc/lib.rs
+++ b/src/librustdoc/lib.rs
@@ -690,10 +690,10 @@ fn run_renderer<'tcx, T: formats::FormatRenderer<'tcx>>(
     tcx: TyCtxt<'tcx>,
 ) -> MainResult {
     match formats::run_format::<T>(krate, renderopts, cache, tcx) {
-        Ok(_) => tcx.sess.has_errors().map_or(Ok(()), Err),
+        Ok(_) => tcx.dcx().has_errors().map_or(Ok(()), Err),
         Err(e) => {
             let mut msg =
-                tcx.sess.struct_err(format!("couldn't generate documentation: {}", e.error));
+                tcx.dcx().struct_err(format!("couldn't generate documentation: {}", e.error));
             let file = e.file.display().to_string();
             if !file.is_empty() {
                 msg.note(format!("failed to create or modify \"{file}\""));
@@ -800,7 +800,7 @@ fn main_args(
         compiler.enter(|queries| {
             let mut gcx = abort_on_err(queries.global_ctxt(), sess);
             if sess.dcx().has_errors_or_lint_errors().is_some() {
-                sess.fatal("Compilation failed, aborting rustdoc");
+                sess.dcx().fatal("Compilation failed, aborting rustdoc");
             }
 
             gcx.enter(|tcx| {
diff --git a/src/librustdoc/passes/collect_trait_impls.rs b/src/librustdoc/passes/collect_trait_impls.rs
index df2e8584b84..fc7ef4bcdfa 100644
--- a/src/librustdoc/passes/collect_trait_impls.rs
+++ b/src/librustdoc/passes/collect_trait_impls.rs
@@ -22,7 +22,7 @@ pub(crate) fn collect_trait_impls(mut krate: Crate, cx: &mut DocContext<'_>) ->
     let tcx = cx.tcx;
     // We need to check if there are errors before running this pass because it would crash when
     // we try to get auto and blanket implementations.
-    if tcx.sess.dcx().has_errors_or_lint_errors().is_some() {
+    if tcx.dcx().has_errors_or_lint_errors().is_some() {
         return krate;
     }
 
diff --git a/src/librustdoc/scrape_examples.rs b/src/librustdoc/scrape_examples.rs
index a343d7afcee..74bec5a2e11 100644
--- a/src/librustdoc/scrape_examples.rs
+++ b/src/librustdoc/scrape_examples.rs
@@ -311,7 +311,7 @@ pub(crate) fn run(
 
         // The visitor might have found a type error, which we need to
         // promote to a fatal error
-        if tcx.sess.dcx().has_errors_or_lint_errors().is_some() {
+        if tcx.dcx().has_errors_or_lint_errors().is_some() {
             return Err(String::from("Compilation failed, aborting rustdoc"));
         }
 
@@ -331,7 +331,7 @@ pub(crate) fn run(
     };
 
     if let Err(e) = inner() {
-        tcx.sess.fatal(e);
+        tcx.dcx().fatal(e);
     }
 
     Ok(())