Remove RunCompiler::emitter.

It's no longer used.

compiler/rustc_driver/src/lib.rs

@@ -35,7 +35,7 @@ use rustc_session::config::{ErrorOutputType, Input, OutputType, PrintRequest, Tr
 use rustc_session::cstore::MetadataLoader;
 use rustc_session::getopts;
 use rustc_session::lint::{Lint, LintId};
-use rustc_session::{config, DiagnosticOutput, Session};
+use rustc_session::{config, Session};
 use rustc_session::{early_error, early_error_no_abort, early_warn};
 use rustc_span::source_map::{FileLoader, FileName};
 use rustc_span::symbol::sym;
@@ -147,19 +147,21 @@ pub struct RunCompiler<'a, 'b> {
     at_args: &'a [String],
     callbacks: &'b mut (dyn Callbacks + Send),
     file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
-    emitter: Option<Box<dyn Write + Send>>,
     make_codegen_backend:
         Option<Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>>,
 }
 
 impl<'a, 'b> RunCompiler<'a, 'b> {
     pub fn new(at_args: &'a [String], callbacks: &'b mut (dyn Callbacks + Send)) -> Self {
-        Self { at_args, callbacks, file_loader: None, emitter: None, make_codegen_backend: None }
+        Self { at_args, callbacks, file_loader: None, make_codegen_backend: None }
     }
 
     /// Set a custom codegen backend.
     ///
-    /// Used by cg_clif.
+    /// Has no uses within this repository, but is used by bjorn3 for "the
+    /// hotswapping branch of cg_clif" for "setting the codegen backend from a
+    /// custom driver where the custom codegen backend has arbitrary data."
+    /// (See #102759.)
     pub fn set_make_codegen_backend(
         &mut self,
         make_codegen_backend: Option<
@@ -170,17 +172,11 @@ impl<'a, 'b> RunCompiler<'a, 'b> {
         self
     }
 
-    /// Emit diagnostics to the specified location.
-    ///
-    /// Used by RLS.
-    pub fn set_emitter(&mut self, emitter: Option<Box<dyn Write + Send>>) -> &mut Self {
-        self.emitter = emitter;
-        self
-    }
-
     /// Load files from sources other than the file system.
     ///
-    /// Used by RLS.
+    /// Has no uses within this repository, but may be used in the future by
+    /// bjorn3 for "hooking rust-analyzer's VFS into rustc at some point for
+    /// running rustc without having to save". (See #102759.)
     pub fn set_file_loader(
         &mut self,
         file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
@@ -191,27 +187,19 @@ impl<'a, 'b> RunCompiler<'a, 'b> {
 
     /// Parse args and run the compiler.
     pub fn run(self) -> interface::Result<()> {
-        run_compiler(
-            self.at_args,
-            self.callbacks,
-            self.file_loader,
-            self.emitter,
-            self.make_codegen_backend,
-        )
+        run_compiler(self.at_args, self.callbacks, self.file_loader, self.make_codegen_backend)
     }
 }
 fn run_compiler(
     at_args: &[String],
     callbacks: &mut (dyn Callbacks + Send),
     file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
-    emitter: Option<Box<dyn Write + Send>>,
     make_codegen_backend: Option<
         Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
     >,
 ) -> interface::Result<()> {
     let args = args::arg_expand_all(at_args);
 
-    let diagnostic_output = emitter.map_or(DiagnosticOutput::Default, DiagnosticOutput::Raw);
     let Some(matches) = handle_options(&args) else { return Ok(()) };
 
     let sopts = config::build_session_options(&matches);
@@ -233,7 +221,6 @@ fn run_compiler(
         output_file: ofile,
         output_dir: odir,
         file_loader,
-        diagnostic_output,
         lint_caps: Default::default(),
         parse_sess_created: None,
         register_lints: None,

compiler/rustc_interface/src/interface.rs

@@ -17,7 +17,7 @@ use rustc_session::config::{self, CheckCfg, ErrorOutputType, Input, OutputFilena
 use rustc_session::early_error;
 use rustc_session::lint;
 use rustc_session::parse::{CrateConfig, ParseSess};
-use rustc_session::{DiagnosticOutput, Session};
+use rustc_session::Session;
 use rustc_span::source_map::{FileLoader, FileName};
 use rustc_span::symbol::sym;
 use std::path::PathBuf;
@@ -247,7 +247,6 @@ pub struct Config {
     pub output_dir: Option<PathBuf>,
     pub output_file: Option<PathBuf>,
     pub file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
-    pub diagnostic_output: DiagnosticOutput,
 
     pub lint_caps: FxHashMap<lint::LintId, lint::Level>,
 
@@ -284,7 +283,6 @@ pub fn create_compiler_and_run<R>(config: Config, f: impl FnOnce(&Compiler) -> R
         config.opts,
         config.crate_cfg,
         config.crate_check_cfg,
-        config.diagnostic_output,
         config.file_loader,
         config.input_path.clone(),
         config.lint_caps,

compiler/rustc_interface/src/tests.rs

@@ -17,7 +17,7 @@ use rustc_session::config::{CFGuard, ExternEntry, LinkerPluginLto, LtoCli, Switc
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
 use rustc_session::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
-use rustc_session::{build_session, getopts, DiagnosticOutput, Session};
+use rustc_session::{build_session, getopts, Session};
 use rustc_span::edition::{Edition, DEFAULT_EDITION};
 use rustc_span::symbol::sym;
 use rustc_span::SourceFileHashAlgorithm;
@@ -40,16 +40,7 @@ fn build_session_options_and_crate_config(matches: getopts::Matches) -> (Options
 fn mk_session(matches: getopts::Matches) -> (Session, CfgSpecs) {
     let registry = registry::Registry::new(&[]);
     let (sessopts, cfg) = build_session_options_and_crate_config(matches);
-    let sess = build_session(
-        sessopts,
-        None,
-        None,
-        registry,
-        DiagnosticOutput::Default,
-        Default::default(),
-        None,
-        None,
-    );
+    let sess = build_session(sessopts, None, None, registry, Default::default(), None, None);
     (sess, cfg)
 }
 

compiler/rustc_interface/src/util.rs

@@ -18,7 +18,7 @@ use rustc_session::config::{self, CrateType};
 use rustc_session::config::{ErrorOutputType, Input, OutputFilenames};
 use rustc_session::lint::{self, BuiltinLintDiagnostics, LintBuffer};
 use rustc_session::parse::CrateConfig;
-use rustc_session::{early_error, filesearch, output, DiagnosticOutput, Session};
+use rustc_session::{early_error, filesearch, output, Session};
 use rustc_span::edition::Edition;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::source_map::FileLoader;
@@ -65,7 +65,6 @@ pub fn create_session(
     sopts: config::Options,
     cfg: FxHashSet<(String, Option<String>)>,
     check_cfg: CheckCfg,
-    diagnostic_output: DiagnosticOutput,
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
     input_path: Option<PathBuf>,
     lint_caps: FxHashMap<lint::LintId, lint::Level>,
@@ -104,7 +103,6 @@ pub fn create_session(
         input_path,
         bundle,
         descriptions,
-        diagnostic_output,
         lint_caps,
         file_loader,
         target_override,

compiler/rustc_session/src/session.rs

@@ -44,7 +44,6 @@ use rustc_target::spec::{
 use std::cell::{self, RefCell};
 use std::env;
 use std::fmt;
-use std::io::Write;
 use std::ops::{Div, Mul};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
@@ -1213,11 +1212,10 @@ fn default_emitter(
     source_map: Lrc<SourceMap>,
     bundle: Option<Lrc<FluentBundle>>,
     fallback_bundle: LazyFallbackBundle,
-    emitter_dest: Option<Box<dyn Write + Send>>,
 ) -> Box<dyn Emitter + sync::Send> {
     let macro_backtrace = sopts.unstable_opts.macro_backtrace;
-    match (sopts.error_format, emitter_dest) {
-        (config::ErrorOutputType::HumanReadable(kind), dst) => {
+    match sopts.error_format {
+        config::ErrorOutputType::HumanReadable(kind) => {
             let (short, color_config) = kind.unzip();
 
             if let HumanReadableErrorType::AnnotateSnippet(_) = kind {
@@ -1230,33 +1228,20 @@ fn default_emitter(
                 );
                 Box::new(emitter.ui_testing(sopts.unstable_opts.ui_testing))
             } else {
-                let emitter = match dst {
-                    None => EmitterWriter::stderr(
-                        color_config,
-                        Some(source_map),
-                        bundle,
-                        fallback_bundle,
-                        short,
-                        sopts.unstable_opts.teach,
-                        sopts.diagnostic_width,
-                        macro_backtrace,
-                    ),
-                    Some(dst) => EmitterWriter::new(
-                        dst,
-                        Some(source_map),
-                        bundle,
-                        fallback_bundle,
-                        short,
-                        false, // no teach messages when writing to a buffer
-                        false, // no colors when writing to a buffer
-                        None,  // no diagnostic width
-                        macro_backtrace,
-                    ),
-                };
+                let emitter = EmitterWriter::stderr(
+                    color_config,
+                    Some(source_map),
+                    bundle,
+                    fallback_bundle,
+                    short,
+                    sopts.unstable_opts.teach,
+                    sopts.diagnostic_width,
+                    macro_backtrace,
+                );
                 Box::new(emitter.ui_testing(sopts.unstable_opts.ui_testing))
             }
         }
-        (config::ErrorOutputType::Json { pretty, json_rendered }, None) => Box::new(
+        config::ErrorOutputType::Json { pretty, json_rendered } => Box::new(
             JsonEmitter::stderr(
                 Some(registry),
                 source_map,
@@ -1269,36 +1254,16 @@ fn default_emitter(
             )
             .ui_testing(sopts.unstable_opts.ui_testing),
         ),
-        (config::ErrorOutputType::Json { pretty, json_rendered }, Some(dst)) => Box::new(
-            JsonEmitter::new(
-                dst,
-                Some(registry),
-                source_map,
-                bundle,
-                fallback_bundle,
-                pretty,
-                json_rendered,
-                sopts.diagnostic_width,
-                macro_backtrace,
-            )
-            .ui_testing(sopts.unstable_opts.ui_testing),
-        ),
     }
 }
 
-pub enum DiagnosticOutput {
-    Default,
-    Raw(Box<dyn Write + Send>),
-}
-
 // JUSTIFICATION: literally session construction
 #[allow(rustc::bad_opt_access)]
 pub fn build_session(
     sopts: config::Options,
     local_crate_source_file: Option<PathBuf>,
     bundle: Option<Lrc<rustc_errors::FluentBundle>>,
     registry: rustc_errors::registry::Registry,
-    diagnostics_output: DiagnosticOutput,
     driver_lint_caps: FxHashMap<lint::LintId, lint::Level>,
     file_loader: Option<Box<dyn FileLoader + Send + Sync + 'static>>,
     target_override: Option<Target>,
@@ -1314,11 +1279,6 @@ pub fn build_session(
     let cap_lints_allow = sopts.lint_cap.map_or(false, |cap| cap == lint::Allow);
     let can_emit_warnings = !(warnings_allow || cap_lints_allow);
 
-    let write_dest = match diagnostics_output {
-        DiagnosticOutput::Default => None,
-        DiagnosticOutput::Raw(write) => Some(write),
-    };
-
     let sysroot = match &sopts.maybe_sysroot {
         Some(sysroot) => sysroot.clone(),
         None => filesearch::get_or_default_sysroot(),
@@ -1351,8 +1311,7 @@ pub fn build_session(
         rustc_errors::DEFAULT_LOCALE_RESOURCES,
         sopts.unstable_opts.translate_directionality_markers,
     );
-    let emitter =
-        default_emitter(&sopts, registry, source_map.clone(), bundle, fallback_bundle, write_dest);
+    let emitter = default_emitter(&sopts, registry, source_map.clone(), bundle, fallback_bundle);
 
     let span_diagnostic = rustc_errors::Handler::with_emitter_and_flags(
         emitter,

src/librustdoc/core.rs

@@ -14,7 +14,6 @@ use rustc_middle::ty::{ParamEnv, Ty, TyCtxt};
 use rustc_resolve as resolve;
 use rustc_session::config::{self, CrateType, ErrorOutputType};
 use rustc_session::lint;
-use rustc_session::DiagnosticOutput;
 use rustc_session::Session;
 use rustc_span::symbol::sym;
 use rustc_span::{source_map, Span, Symbol};
@@ -286,7 +285,6 @@ pub(crate) fn create_config(
         output_file: None,
         output_dir: None,
         file_loader: None,
-        diagnostic_output: DiagnosticOutput::Default,
         lint_caps,
         parse_sess_created: None,
         register_lints: Some(Box::new(crate::lint::register_lints)),

src/librustdoc/doctest.rs

@@ -14,7 +14,7 @@ use rustc_parse::maybe_new_parser_from_source_str;
 use rustc_parse::parser::attr::InnerAttrPolicy;
 use rustc_session::config::{self, CrateType, ErrorOutputType};
 use rustc_session::parse::ParseSess;
-use rustc_session::{lint, DiagnosticOutput, Session};
+use rustc_session::{lint, Session};
 use rustc_span::edition::Edition;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::sym;
@@ -100,7 +100,6 @@ pub(crate) fn run(options: RustdocOptions) -> Result<(), ErrorGuaranteed> {
         output_file: None,
         output_dir: None,
         file_loader: None,
-        diagnostic_output: DiagnosticOutput::Default,
         lint_caps,
         parse_sess_created: None,
         register_lints: Some(Box::new(crate::lint::register_lints)),

src/test/run-make-fulldeps/issue-19371/foo.rs

@@ -5,7 +5,6 @@ extern crate rustc_driver;
 extern crate rustc_session;
 extern crate rustc_span;
 
-use rustc_session::DiagnosticOutput;
 use rustc_session::config::{Input, Options, OutputType, OutputTypes};
 use rustc_interface::interface;
 use rustc_span::source_map::FileName;
@@ -55,7 +54,6 @@ fn compile(code: String, output: PathBuf, sysroot: PathBuf) {
         output_file: Some(output),
         output_dir: None,
         file_loader: None,
-        diagnostic_output: DiagnosticOutput::Default,
         lint_caps: Default::default(),
         parse_sess_created: None,
         register_lints: None,