Fewer early errors.

`build_session` is passed an `EarlyErrorHandler` and then constructs a
`Handler`. But the `EarlyErrorHandler` is still used for some time after
that.

This commit changes `build_session` so it consumes the passed
`EarlyErrorHandler`, and also drops it as soon as the `Handler` is
built. As a result, `parse_cfg` and `parse_check_cfg` now take a
`Handler` instead of an `EarlyErrorHandler`.

Author: nnethercote

compiler/rustc_interface/src/interface.rs

@@ -42,7 +42,7 @@ pub struct Compiler {
 }
 
 /// Converts strings provided as `--cfg [cfgspec]` into a `Cfg`.
-pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg {
+pub(crate) fn parse_cfg(handler: &Handler, cfgs: Vec<String>) -> Cfg {
     cfgs.into_iter()
         .map(|s| {
             let sess = ParseSess::with_silent_emitter(Some(format!(
@@ -52,10 +52,14 @@ pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg {
 
             macro_rules! error {
                 ($reason: expr) => {
-                    handler.early_error(format!(
-                        concat!("invalid `--cfg` argument: `{}` (", $reason, ")"),
-                        s
-                    ));
+                    #[allow(rustc::untranslatable_diagnostic)]
+                    #[allow(rustc::diagnostic_outside_of_impl)]
+                    handler
+                        .struct_fatal(format!(
+                            concat!("invalid `--cfg` argument: `{}` (", $reason, ")"),
+                            s
+                        ))
+                        .emit();
                 };
             }
 
@@ -97,7 +101,7 @@ pub(crate) fn parse_cfg(handler: &EarlyErrorHandler, cfgs: Vec<String>) -> Cfg {
 }
 
 /// Converts strings provided as `--check-cfg [specs]` into a `CheckCfg`.
-pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -> CheckCfg {
+pub(crate) fn parse_check_cfg(handler: &Handler, specs: Vec<String>) -> CheckCfg {
     // If any --check-cfg is passed then exhaustive_values and exhaustive_names
     // are enabled by default.
     let exhaustive_names = !specs.is_empty();
@@ -113,10 +117,14 @@ pub(crate) fn parse_check_cfg(handler: &EarlyErrorHandler, specs: Vec<String>) -
 
         macro_rules! error {
             ($reason:expr) => {
-                handler.early_error(format!(
-                    concat!("invalid `--check-cfg` argument: `{}` (", $reason, ")"),
-                    s
-                ))
+                #[allow(rustc::untranslatable_diagnostic)]
+                #[allow(rustc::diagnostic_outside_of_impl)]
+                handler
+                    .struct_fatal(format!(
+                        concat!("invalid `--check-cfg` argument: `{}` (", $reason, ")"),
+                        s
+                    ))
+                    .emit()
             };
         }
 
@@ -388,13 +396,13 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
         || {
             crate::callbacks::setup_callbacks();
 
-            let handler = EarlyErrorHandler::new(config.opts.error_format);
+            let early_handler = EarlyErrorHandler::new(config.opts.error_format);
 
             let codegen_backend = if let Some(make_codegen_backend) = config.make_codegen_backend {
                 make_codegen_backend(&config.opts)
             } else {
                 util::get_codegen_backend(
-                    &handler,
+                    &early_handler,
                     &config.opts.maybe_sysroot,
                     config.opts.unstable_opts.codegen_backend.as_deref(),
                 )
@@ -411,7 +419,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             ) {
                 Ok(bundle) => bundle,
                 Err(e) => {
-                    handler.early_error(format!("failed to load fluent bundle: {e}"));
+                    early_handler.early_error(format!("failed to load fluent bundle: {e}"));
                 }
             };
 
@@ -422,7 +430,7 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
             let target_override = codegen_backend.target_override(&config.opts);
 
             let mut sess = rustc_session::build_session(
-                &handler,
+                early_handler,
                 config.opts,
                 CompilerIO {
                     input: config.input,
@@ -444,12 +452,12 @@ pub fn run_compiler<R: Send>(config: Config, f: impl FnOnce(&Compiler) -> R + Se
 
             codegen_backend.init(&sess);
 
-            let cfg = parse_cfg(&handler, config.crate_cfg);
+            let cfg = parse_cfg(&sess.diagnostic(), config.crate_cfg);
             let mut cfg = config::build_configuration(&sess, cfg);
             util::add_configuration(&mut cfg, &mut sess, &*codegen_backend);
             sess.parse_sess.config = cfg;
 
-            let mut check_cfg = parse_check_cfg(&handler, config.crate_check_cfg);
+            let mut check_cfg = parse_check_cfg(&sess.diagnostic(), config.crate_check_cfg);
             check_cfg.fill_well_known(&sess.target);
             sess.parse_sess.check_config = check_cfg;
 

compiler/rustc_interface/src/tests.rs

@@ -26,10 +26,9 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
 fn mk_session(matches: getopts::Matches) -> (Session, Cfg) {
-    let mut handler = EarlyErrorHandler::new(ErrorOutputType::default());
+    let mut early_handler = EarlyErrorHandler::new(ErrorOutputType::default());
     let registry = registry::Registry::new(&[]);
-    let sessopts = build_session_options(&mut handler, &matches);
-    let cfg = parse_cfg(&handler, matches.opt_strs("cfg"));
+    let sessopts = build_session_options(&mut early_handler, &matches);
     let temps_dir = sessopts.unstable_opts.temps_dir.as_deref().map(PathBuf::from);
     let io = CompilerIO {
         input: Input::Str { name: FileName::Custom(String::new()), input: String::new() },
@@ -38,7 +37,7 @@ fn mk_session(matches: getopts::Matches) -> (Session, Cfg) {
         temps_dir,
     };
     let sess = build_session(
-        &handler,
+        early_handler,
         sessopts,
         io,
         None,
@@ -52,6 +51,7 @@ fn mk_session(matches: getopts::Matches) -> (Session, Cfg) {
         Arc::default(),
         Default::default(),
     );
+    let cfg = parse_cfg(&sess.diagnostic(), matches.opt_strs("cfg"));
     (sess, cfg)
 }
 

compiler/rustc_session/messages.ftl

@@ -16,6 +16,8 @@ session_crate_name_invalid = crate names cannot start with a `-`, but `{$s}` has
 
 session_expr_parentheses_needed = parentheses are required to parse this as an expression
 
+session_failed_to_create_profiler = failed to create profiler: {$err}
+
 session_feature_diagnostic_for_issue =
     see issue #{$n} <https://github.com/rust-lang/rust/issues/{$n}> for more information
 
@@ -73,6 +75,7 @@ session_not_supported = not supported
 session_nul_in_c_str = null characters in C string literals are not supported
 
 session_octal_float_literal_not_supported = octal float literal is not supported
+
 session_optimization_fuel_exhausted = optimization-fuel-exhausted: {$msg}
 
 session_profile_sample_use_file_does_not_exist = file `{$path}` passed to `-C profile-sample-use` does not exist.

compiler/rustc_session/src/errors.rs

@@ -444,3 +444,9 @@ pub(crate) struct FunctionReturnRequiresX86OrX8664;
 #[derive(Diagnostic)]
 #[diag(session_function_return_thunk_extern_requires_non_large_code_model)]
 pub(crate) struct FunctionReturnThunkExternRequiresNonLargeCodeModel;
+
+#[derive(Diagnostic)]
+#[diag(session_failed_to_create_profiler)]
+pub struct FailedToCreateProfiler {
+    pub err: String,
+}

compiler/rustc_session/src/session.rs

@@ -24,7 +24,7 @@ use rustc_errors::registry::Registry;
 use rustc_errors::{
     error_code, fallback_fluent_bundle, DiagnosticBuilder, DiagnosticId, DiagnosticMessage,
     ErrorGuaranteed, FluentBundle, Handler, IntoDiagnostic, LazyFallbackBundle, MultiSpan, Noted,
-    SubdiagnosticMessage, TerminalUrl,
+    TerminalUrl,
 };
 use rustc_macros::HashStable_Generic;
 pub use rustc_span::def_id::StableCrateId;
@@ -1349,7 +1349,7 @@ fn default_emitter(
 // JUSTIFICATION: literally session construction
 #[allow(rustc::bad_opt_access)]
 pub fn build_session(
-    handler: &EarlyErrorHandler,
+    early_handler: EarlyErrorHandler,
     sopts: config::Options,
     io: CompilerIO,
     bundle: Option<Lrc<rustc_errors::FluentBundle>>,
@@ -1379,12 +1379,13 @@ pub fn build_session(
         None => filesearch::get_or_default_sysroot().expect("Failed finding sysroot"),
     };
 
-    let target_cfg = config::build_target_config(handler, &sopts, target_override, &sysroot);
+    let target_cfg = config::build_target_config(&early_handler, &sopts, target_override, &sysroot);
     let host_triple = TargetTriple::from_triple(config::host_triple());
-    let (host, target_warnings) = Target::search(&host_triple, &sysroot)
-        .unwrap_or_else(|e| handler.early_error(format!("Error loading host specification: {e}")));
+    let (host, target_warnings) = Target::search(&host_triple, &sysroot).unwrap_or_else(|e| {
+        early_handler.early_error(format!("Error loading host specification: {e}"))
+    });
     for warning in target_warnings.warning_messages() {
-        handler.early_warn(warning)
+        early_handler.early_warn(warning)
     }
 
     let loader = file_loader.unwrap_or_else(|| Box::new(RealFileLoader));
@@ -1413,6 +1414,10 @@ pub fn build_session(
         span_diagnostic = span_diagnostic.with_ice_file(ice_file);
     }
 
+    // Now that the proper handler has been constructed, drop the early handler
+    // to prevent accidental use.
+    drop(early_handler);
+
     let self_profiler = if let SwitchWithOptPath::Enabled(ref d) = sopts.unstable_opts.self_profile
     {
         let directory =
@@ -1427,7 +1432,7 @@ pub fn build_session(
         match profiler {
             Ok(profiler) => Some(Arc::new(profiler)),
             Err(e) => {
-                handler.early_warn(format!("failed to create profiler: {e}"));
+                span_diagnostic.emit_warning(errors::FailedToCreateProfiler { err: e.to_string() });
                 None
             }
         }
@@ -1471,7 +1476,13 @@ pub fn build_session(
 
     // Check jobserver before getting `jobserver::client`.
     jobserver::check(|err| {
-        handler.early_warn_with_note(err, "the build environment is likely misconfigured")
+        #[allow(rustc::untranslatable_diagnostic)]
+        #[allow(rustc::diagnostic_outside_of_impl)]
+        parse_sess
+            .span_diagnostic
+            .struct_warn(err)
+            .note("the build environment is likely misconfigured")
+            .emit()
     });
 
     let sess = Session {
@@ -1781,16 +1792,6 @@ impl EarlyErrorHandler {
     pub fn early_warn(&self, msg: impl Into<DiagnosticMessage>) {
         self.handler.struct_warn(msg).emit()
     }
-
-    #[allow(rustc::untranslatable_diagnostic)]
-    #[allow(rustc::diagnostic_outside_of_impl)]
-    pub fn early_warn_with_note(
-        &self,
-        msg: impl Into<DiagnosticMessage>,
-        note: impl Into<SubdiagnosticMessage>,
-    ) {
-        self.handler.struct_warn(msg).note(note).emit()
-    }
 }
 
 fn mk_emitter(output: ErrorOutputType) -> Box<DynEmitter> {

tests/run-make/jobserver-error/cannot_open_fd.stderr

@@ -4,3 +4,5 @@ warning: failed to connect to jobserver from environment variable `MAKEFLAGS="--
 
 error: no input filename given
 
+warning: 1 warning emitted
+

tests/run-make/jobserver-error/not_a_pipe.stderr

@@ -2,3 +2,5 @@ warning: failed to connect to jobserver from environment variable `MAKEFLAGS="--
   |
   = note: the build environment is likely misconfigured
 
+warning: 1 warning emitted
+