Remove RunCompiler and related things.

I tried removing two methods in `RunCompiler` that were marked as being used by
RLS. Tugging on this loose thread led to lots of code removal, including:
- `RunCompiler`
- `DiagnosticOutput`
- `FileLoader` and `RealFileLoader`
- Three fields in `Config`

Note also that the "Ideally, ..." comment in `SourceMap::load_binary_file` is
removed because it's no longer relevant.

Author: nnethercote

compiler/rustc_driver/src/lib.rs

@@ -35,9 +35,9 @@ 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::source_map::FileName;
 use rustc_span::symbol::sym;
 use rustc_target::json::ToJson;
 
@@ -139,76 +139,13 @@ pub fn diagnostics_registry() -> Registry {
     Registry::new(rustc_error_codes::DIAGNOSTICS)
 }
 
-/// This is the primary entry point for rustc.
-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 }
-    }
-
-    /// Set a custom codegen backend.
-    ///
-    /// Used by cg_clif.
-    pub fn set_make_codegen_backend(
-        &mut self,
-        make_codegen_backend: Option<
-            Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
-        >,
-    ) -> &mut Self {
-        self.make_codegen_backend = make_codegen_backend;
-        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.
-    pub fn set_file_loader(
-        &mut self,
-        file_loader: Option<Box<dyn FileLoader + Send + Sync>>,
-    ) -> &mut Self {
-        self.file_loader = file_loader;
-        self
-    }
-
-    /// 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,
-        )
-    }
-}
-fn run_compiler(
+// Primary entry point used by rustc, clippy, and miri.
+pub 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);
@@ -229,13 +166,10 @@ fn run_compiler(
         input_path: None,
         output_file: ofile,
         output_dir: odir,
-        file_loader,
-        diagnostic_output,
         lint_caps: Default::default(),
         parse_sess_created: None,
         register_lints: None,
         override_queries: None,
-        make_codegen_backend,
         registry: diagnostics_registry(),
     };
 
@@ -1371,7 +1305,7 @@ pub fn main() -> ! {
                 })
             })
             .collect::<Vec<_>>();
-        RunCompiler::new(&args, &mut callbacks).run()
+        run_compiler(&args, &mut callbacks)
     });
 
     if callbacks.time_passes {

compiler/rustc_expand/src/module.rs

@@ -4,7 +4,6 @@ use rustc_ast::{token, AttrVec, Attribute, Inline, Item, ModSpans};
 use rustc_errors::{struct_span_err, DiagnosticBuilder, ErrorGuaranteed};
 use rustc_parse::new_parser_from_file;
 use rustc_parse::validate_attr;
-use rustc_session::parse::ParseSess;
 use rustc_session::Session;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
@@ -151,7 +150,7 @@ fn mod_file_path<'a>(
         DirOwnership::Owned { relative } => relative,
         DirOwnership::UnownedViaBlock => None,
     };
-    let result = default_submod_path(&sess.parse_sess, ident, relative, dir_path);
+    let result = default_submod_path(ident, relative, dir_path);
     match dir_ownership {
         DirOwnership::Owned { .. } => result,
         DirOwnership::UnownedViaBlock => Err(ModError::ModInBlock(match result {
@@ -201,7 +200,6 @@ fn mod_file_path_from_attr(
 /// Returns a path to a module.
 // Public for rustfmt usage.
 pub fn default_submod_path<'a>(
-    sess: &'a ParseSess,
     ident: Ident,
     relative: Option<Ident>,
     dir_path: &Path,
@@ -223,8 +221,8 @@ pub fn default_submod_path<'a>(
         format!("{}{}{}mod.rs", relative_prefix, ident.name, path::MAIN_SEPARATOR);
     let default_path = dir_path.join(&default_path_str);
     let secondary_path = dir_path.join(&secondary_path_str);
-    let default_exists = sess.source_map().file_exists(&default_path);
-    let secondary_exists = sess.source_map().file_exists(&secondary_path);
+    let default_exists = default_path.exists();
+    let secondary_exists = secondary_path.exists();
 
     match (default_exists, secondary_exists) {
         (true, false) => Ok(ModulePathSuccess {

compiler/rustc_interface/src/interface.rs

@@ -17,8 +17,8 @@ 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_span::source_map::{FileLoader, FileName};
+use rustc_session::Session;
+use rustc_span::source_map::FileName;
 use rustc_span::symbol::sym;
 use std::path::PathBuf;
 use std::result;
@@ -246,8 +246,6 @@ pub struct Config {
     pub input_path: Option<PathBuf>,
     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>,
 
@@ -268,10 +266,6 @@ pub struct Config {
     pub override_queries:
         Option<fn(&Session, &mut ty::query::Providers, &mut ty::query::ExternProviders)>,
 
-    /// This is a callback from the driver that is called to create a codegen backend.
-    pub make_codegen_backend:
-        Option<Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>>,
-
     /// Registry of diagnostics codes.
     pub registry: Registry,
 }
@@ -284,11 +278,8 @@ 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,
-        config.make_codegen_backend,
         registry.clone(),
     );
 

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);
     (sess, cfg)
 }
 

compiler/rustc_interface/src/util.rs

@@ -18,10 +18,9 @@ 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;
 use rustc_span::symbol::{sym, Symbol};
 use std::env;
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
@@ -65,23 +64,14 @@ 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>,
-    make_codegen_backend: Option<
-        Box<dyn FnOnce(&config::Options) -> Box<dyn CodegenBackend> + Send>,
-    >,
     descriptions: Registry,
 ) -> (Lrc<Session>, Lrc<Box<dyn CodegenBackend>>) {
-    let codegen_backend = if let Some(make_codegen_backend) = make_codegen_backend {
-        make_codegen_backend(&sopts)
-    } else {
-        get_codegen_backend(
-            &sopts.maybe_sysroot,
-            sopts.unstable_opts.codegen_backend.as_ref().map(|name| &name[..]),
-        )
-    };
+    let codegen_backend = get_codegen_backend(
+        &sopts.maybe_sysroot,
+        sopts.unstable_opts.codegen_backend.as_ref().map(|name| &name[..]),
+    );
 
     // target_override is documented to be called before init(), so this is okay
     let target_override = codegen_backend.target_override(&sopts);
@@ -99,16 +89,8 @@ pub fn create_session(
         }
     };
 
-    let mut sess = session::build_session(
-        sopts,
-        input_path,
-        bundle,
-        descriptions,
-        diagnostic_output,
-        lint_caps,
-        file_loader,
-        target_override,
-    );
+    let mut sess =
+        session::build_session(sopts, input_path, bundle, descriptions, lint_caps, target_override);
 
     codegen_backend.init(&sess);