Auto merge of #64272 - Mark-Simulacrum:parallel-handler, r=estebank

Refactor librustc_errors::Handler API

This should be reviewed by-commit.

The last commit moves all fields into an inner struct behind a single lock; this is done to prevent possible deadlocks in a multi-threaded compiler, as well as inconsistent state observation.

src/librustc/dep_graph/graph.rs

@@ -1,4 +1,4 @@
-use errors::{Diagnostic, DiagnosticBuilder};
+use errors::Diagnostic;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
@@ -819,7 +819,7 @@ impl DepGraph {
             let handle = tcx.sess.diagnostic();
 
             for diagnostic in diagnostics {
-                DiagnosticBuilder::new_diagnostic(handle, diagnostic).emit();
+                handle.emit_diagnostic(&diagnostic);
             }
 
             // Mark the node as green now that diagnostics are emitted

src/librustc/infer/error_reporting/mod.rs

@@ -1119,7 +1119,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                     Some((expected, found)) => Some((expected, found)),
                     None => {
                         // Derived error. Cancel the emitter.
-                        self.tcx.sess.diagnostic().cancel(diag);
+                        diag.cancel();
                         return;
                     }
                 };

src/librustc/session/config.rs

@@ -1855,7 +1855,7 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
 struct NullEmitter;
 
 impl errors::emitter::Emitter for NullEmitter {
-    fn emit_diagnostic(&mut self, _: &errors::DiagnosticBuilder<'_>) {}
+    fn emit_diagnostic(&mut self, _: &errors::Diagnostic) {}
 }
 
 // Converts strings provided as `--cfg [cfgspec]` into a `crate_cfg`.

src/librustc/session/config/tests.rs

@@ -87,7 +87,7 @@ fn test_can_print_warnings() {
         let registry = errors::registry::Registry::new(&[]);
         let (sessopts, _) = build_session_options_and_crate_config(&matches);
         let sess = build_session(sessopts, None, registry);
-        assert!(!sess.diagnostic().flags.can_emit_warnings);
+        assert!(!sess.diagnostic().can_emit_warnings());
     });
 
     syntax::with_default_globals(|| {
@@ -97,15 +97,15 @@ fn test_can_print_warnings() {
         let registry = errors::registry::Registry::new(&[]);
         let (sessopts, _) = build_session_options_and_crate_config(&matches);
         let sess = build_session(sessopts, None, registry);
-        assert!(sess.diagnostic().flags.can_emit_warnings);
+        assert!(sess.diagnostic().can_emit_warnings());
     });
 
     syntax::with_default_globals(|| {
         let matches = optgroups().parse(&["-Adead_code".to_string()]).unwrap();
         let registry = errors::registry::Registry::new(&[]);
         let (sessopts, _) = build_session_options_and_crate_config(&matches);
         let sess = build_session(sessopts, None, registry);
-        assert!(sess.diagnostic().flags.can_emit_warnings);
+        assert!(sess.diagnostic().can_emit_warnings());
     });
 }
 

src/librustc/session/mod.rs

@@ -365,12 +365,6 @@ impl Session {
     pub fn span_note_without_error<S: Into<MultiSpan>>(&self, sp: S, msg: &str) {
         self.diagnostic().span_note_without_error(sp, msg)
     }
-    pub fn span_unimpl<S: Into<MultiSpan>>(&self, sp: S, msg: &str) -> ! {
-        self.diagnostic().span_unimpl(sp, msg)
-    }
-    pub fn unimpl(&self, msg: &str) -> ! {
-        self.diagnostic().unimpl(msg)
-    }
 
     pub fn buffer_lint<S: Into<MultiSpan>>(
         &self,
@@ -1040,6 +1034,7 @@ fn default_emitter(
     source_map: &Lrc<source_map::SourceMap>,
     emitter_dest: Option<Box<dyn Write + Send>>,
 ) -> Box<dyn Emitter + sync::Send> {
+    let external_macro_backtrace = sopts.debugging_opts.external_macro_backtrace;
     match (sopts.error_format, emitter_dest) {
         (config::ErrorOutputType::HumanReadable(kind), dst) => {
             let (short, color_config) = kind.unzip();
@@ -1048,6 +1043,7 @@ fn default_emitter(
                 let emitter = AnnotateSnippetEmitterWriter::new(
                     Some(source_map.clone()),
                     short,
+                    external_macro_backtrace,
                 );
                 Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing))
             } else {
@@ -1058,6 +1054,7 @@ fn default_emitter(
                         short,
                         sopts.debugging_opts.teach,
                         sopts.debugging_opts.terminal_width,
+                        external_macro_backtrace,
                     ),
                     Some(dst) => EmitterWriter::new(
                         dst,
@@ -1066,6 +1063,7 @@ fn default_emitter(
                         false, // no teach messages when writing to a buffer
                         false, // no colors when writing to a buffer
                         None,  // no terminal width
+                        external_macro_backtrace,
                     ),
                 };
                 Box::new(emitter.ui_testing(sopts.debugging_opts.ui_testing))
@@ -1077,6 +1075,7 @@ fn default_emitter(
                 source_map.clone(),
                 pretty,
                 json_rendered,
+                external_macro_backtrace,
             ).ui_testing(sopts.debugging_opts.ui_testing),
         ),
         (config::ErrorOutputType::Json { pretty, json_rendered }, Some(dst)) => Box::new(
@@ -1086,6 +1085,7 @@ fn default_emitter(
                 source_map.clone(),
                 pretty,
                 json_rendered,
+                external_macro_backtrace,
             ).ui_testing(sopts.debugging_opts.ui_testing),
         ),
     }
@@ -1382,27 +1382,27 @@ pub fn early_error(output: config::ErrorOutputType, msg: &str) -> ! {
     let emitter: Box<dyn Emitter + sync::Send> = match output {
         config::ErrorOutputType::HumanReadable(kind) => {
             let (short, color_config) = kind.unzip();
-            Box::new(EmitterWriter::stderr(color_config, None, short, false, None))
+            Box::new(EmitterWriter::stderr(color_config, None, short, false, None, false))
         }
         config::ErrorOutputType::Json { pretty, json_rendered } =>
-            Box::new(JsonEmitter::basic(pretty, json_rendered)),
+            Box::new(JsonEmitter::basic(pretty, json_rendered, false)),
     };
     let handler = errors::Handler::with_emitter(true, None, emitter);
-    handler.emit(&MultiSpan::new(), msg, errors::Level::Fatal);
+    handler.struct_fatal(msg).emit();
     errors::FatalError.raise();
 }
 
 pub fn early_warn(output: config::ErrorOutputType, msg: &str) {
     let emitter: Box<dyn Emitter + sync::Send> = match output {
         config::ErrorOutputType::HumanReadable(kind) => {
             let (short, color_config) = kind.unzip();
-            Box::new(EmitterWriter::stderr(color_config, None, short, false, None))
+            Box::new(EmitterWriter::stderr(color_config, None, short, false, None, false))
         }
         config::ErrorOutputType::Json { pretty, json_rendered } =>
-            Box::new(JsonEmitter::basic(pretty, json_rendered)),
+            Box::new(JsonEmitter::basic(pretty, json_rendered, false)),
     };
     let handler = errors::Handler::with_emitter(true, None, emitter);
-    handler.emit(&MultiSpan::new(), msg, errors::Level::Warning);
+    handler.struct_warn(msg).emit();
 }
 
 pub type CompileResult = Result<(), ErrorReported>;

src/librustc/ty/query/plumbing.rs

@@ -330,14 +330,13 @@ impl<'tcx> TyCtxt<'tcx> {
                 let mut i = 0;
 
                 while let Some(query) = current_query {
-                    let mut db = DiagnosticBuilder::new(icx.tcx.sess.diagnostic(),
-                        Level::FailureNote,
+                    let mut diag = Diagnostic::new(Level::FailureNote,
                         &format!("#{} [{}] {}",
                                  i,
                                  query.info.query.name(),
                                  query.info.query.describe(icx.tcx)));
-                    db.set_span(icx.tcx.sess.source_map().def_span(query.info.span));
-                    icx.tcx.sess.diagnostic().force_print_db(db);
+                    diag.span = icx.tcx.sess.source_map().def_span(query.info.span).into();
+                    icx.tcx.sess.diagnostic().force_print_diagnostic(diag);
 
                     current_query = query.parent.clone();
                     i += 1;

src/librustc_codegen_ssa/back/write.rs

@@ -22,12 +22,11 @@ use rustc::util::common::{time_depth, set_time_depth, print_time_passes_entry};
 use rustc::util::profiling::SelfProfiler;
 use rustc_fs_util::link_or_copy;
 use rustc_data_structures::svh::Svh;
-use rustc_errors::{Handler, Level, DiagnosticBuilder, FatalError, DiagnosticId};
+use rustc_errors::{Handler, Level, FatalError, DiagnosticId};
 use rustc_errors::emitter::{Emitter};
 use rustc_target::spec::MergeFunctions;
 use syntax::attr;
 use syntax::ext::hygiene::ExpnId;
-use syntax_pos::MultiSpan;
 use syntax_pos::symbol::{Symbol, sym};
 use jobserver::{Client, Acquired};
 
@@ -1725,7 +1724,7 @@ impl SharedEmitter {
 }
 
 impl Emitter for SharedEmitter {
-    fn emit_diagnostic(&mut self, db: &DiagnosticBuilder<'_>) {
+    fn emit_diagnostic(&mut self, db: &rustc_errors::Diagnostic) {
         drop(self.sender.send(SharedEmitterMessage::Diagnostic(Diagnostic {
             msg: db.message(),
             code: db.code.clone(),
@@ -1760,19 +1759,12 @@ impl SharedEmitterMain {
             match message {
                 Ok(SharedEmitterMessage::Diagnostic(diag)) => {
                     let handler = sess.diagnostic();
-                    match diag.code {
-                        Some(ref code) => {
-                            handler.emit_with_code(&MultiSpan::new(),
-                                                   &diag.msg,
-                                                   code.clone(),
-                                                   diag.lvl);
-                        }
-                        None => {
-                            handler.emit(&MultiSpan::new(),
-                                         &diag.msg,
-                                         diag.lvl);
-                        }
+                    let mut d = rustc_errors::Diagnostic::new(diag.lvl, &diag.msg);
+                    if let Some(code) = diag.code {
+                        d.code(code);
                     }
+                    handler.emit_diagnostic(&d);
+                    handler.abort_if_errors_and_should_abort();
                 }
                 Ok(SharedEmitterMessage::InlineAsmError(cookie, msg)) => {
                     sess.span_err(ExpnId::from_u32(cookie).expn_data().call_site, &msg)

src/librustc_driver/lib.rs

@@ -66,7 +66,7 @@ use syntax::source_map::FileLoader;
 use syntax::feature_gate::{GatedCfg, UnstableFeatures};
 use syntax::parse::{self, PResult};
 use syntax::symbol::sym;
-use syntax_pos::{DUMMY_SP, MultiSpan, FileName};
+use syntax_pos::{DUMMY_SP, FileName};
 
 pub mod pretty;
 mod args;
@@ -1196,15 +1196,16 @@ pub fn report_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
         false,
         false,
         None,
+        false,
     ));
     let handler = errors::Handler::with_emitter(true, None, emitter);
 
     // a .span_bug or .bug call has already printed what
     // it wants to print.
     if !info.payload().is::<errors::ExplicitBug>() {
-        handler.emit(&MultiSpan::new(),
-                     "unexpected panic",
-                     errors::Level::Bug);
+        let d = errors::Diagnostic::new(errors::Level::Bug, "unexpected panic");
+        handler.emit_diagnostic(&d);
+        handler.abort_if_errors_and_should_abort();
     }
 
     let mut xs: Vec<Cow<'static, str>> = vec![
@@ -1224,9 +1225,7 @@ pub fn report_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
     }
 
     for note in &xs {
-        handler.emit(&MultiSpan::new(),
-                     note,
-                     errors::Level::Note);
+        handler.note_without_error(&note);
     }
 
     // If backtraces are enabled, also print the query stack

src/librustc_errors/annotate_snippet_emitter_writer.rs

@@ -7,7 +7,7 @@
 
 use syntax_pos::{SourceFile, MultiSpan, Loc};
 use crate::{
-    Level, CodeSuggestion, DiagnosticBuilder, Emitter,
+    Level, CodeSuggestion, Diagnostic, Emitter,
     SourceMapperDyn, SubDiagnostic, DiagnosticId
 };
 use crate::emitter::FileWithAnnotatedLines;
@@ -25,19 +25,21 @@ pub struct AnnotateSnippetEmitterWriter {
     short_message: bool,
     /// If true, will normalize line numbers with `LL` to prevent noise in UI test diffs.
     ui_testing: bool,
+
+    external_macro_backtrace: bool,
 }
 
 impl Emitter for AnnotateSnippetEmitterWriter {
     /// The entry point for the diagnostics generation
-    fn emit_diagnostic(&mut self, db: &DiagnosticBuilder<'_>) {
+    fn emit_diagnostic(&mut self, db: &Diagnostic) {
         let mut children = db.children.clone();
         let (mut primary_span, suggestions) = self.primary_span_formatted(&db);
 
         self.fix_multispans_in_std_macros(&self.source_map,
                                           &mut primary_span,
                                           &mut children,
                                           &db.level,
-                                          db.handler().flags.external_macro_backtrace);
+                                          self.external_macro_backtrace);
 
         self.emit_messages_default(&db.level,
                                    db.message(),
@@ -163,12 +165,14 @@ impl<'a>  DiagnosticConverter<'a> {
 impl AnnotateSnippetEmitterWriter {
     pub fn new(
         source_map: Option<Lrc<SourceMapperDyn>>,
-        short_message: bool
+        short_message: bool,
+        external_macro_backtrace: bool,
     ) -> Self {
         Self {
             source_map,
             short_message,
             ui_testing: false,
+            external_macro_backtrace,
         }
     }
 

src/librustc_errors/diagnostic_builder.rs

@@ -99,17 +99,9 @@ impl<'a> DerefMut for DiagnosticBuilder<'a> {
 }
 
 impl<'a> DiagnosticBuilder<'a> {
-    pub fn handler(&self) -> &'a Handler{
-        self.0.handler
-    }
-
     /// Emit the diagnostic.
     pub fn emit(&mut self) {
-        if self.cancelled() {
-            return;
-        }
-
-        self.0.handler.emit_db(&self);
+        self.0.handler.emit_diagnostic(&self);
         self.cancel();
     }
 
@@ -354,7 +346,7 @@ impl<'a> DiagnosticBuilder<'a> {
 
     /// Convenience function for internal use, clients should use one of the
     /// struct_* methods on Handler.
-    pub fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
+    crate fn new(handler: &'a Handler, level: Level, message: &str) -> DiagnosticBuilder<'a> {
         DiagnosticBuilder::new_with_code(handler, level, None, message)
     }
 
@@ -371,7 +363,8 @@ impl<'a> DiagnosticBuilder<'a> {
 
     /// Creates a new `DiagnosticBuilder` with an already constructed
     /// diagnostic.
-    pub fn new_diagnostic(handler: &'a Handler, diagnostic: Diagnostic) -> DiagnosticBuilder<'a> {
+    crate fn new_diagnostic(handler: &'a Handler, diagnostic: Diagnostic)
+                         -> DiagnosticBuilder<'a> {
         DiagnosticBuilder(Box::new(DiagnosticBuilderInner {
             handler,
             diagnostic,