span: move MultiSpan

`MultiSpan` contains labels, which are more complicated with the
introduction of diagnostic translation and will use types from
`rustc_errors` - however, `rustc_errors` depends on `rustc_span` so
`rustc_span` cannot use types like `DiagnosticMessage` without
dependency cycles. Introduce a new `rustc_error_messages` crate that can
contain `DiagnosticMessage` and `MultiSpan`.

Signed-off-by: David Wood <david.wood@huawei.com>

compiler/rustc_errors/src/annotate_snippet_emitter_writer.rs

@@ -7,12 +7,12 @@
 
 use crate::emitter::FileWithAnnotatedLines;
 use crate::snippet::Line;
-use crate::{CodeSuggestion, Diagnostic, DiagnosticId, Emitter, Level, SubDiagnostic};
+use crate::{CodeSuggestion, Diagnostic, DiagnosticId, Emitter, Level, MultiSpan, SubDiagnostic};
 use annotate_snippets::display_list::{DisplayList, FormatOptions};
 use annotate_snippets::snippet::*;
 use rustc_data_structures::sync::Lrc;
 use rustc_span::source_map::SourceMap;
-use rustc_span::{MultiSpan, SourceFile};
+use rustc_span::SourceFile;
 
 /// Generates diagnostics using annotate-snippet
 pub struct AnnotateSnippetEmitterWriter {

compiler/rustc_errors/src/diagnostic.rs

@@ -1,15 +1,13 @@
 use crate::snippet::Style;
-use crate::CodeSuggestion;
-use crate::Level;
-use crate::Substitution;
-use crate::SubstitutionPart;
-use crate::SuggestionStyle;
-use crate::ToolMetadata;
+use crate::{
+    CodeSuggestion, DiagnosticMessage, Level, MultiSpan, Substitution, SubstitutionPart,
+    SuggestionStyle, ToolMetadata,
+};
 use rustc_data_structures::stable_map::FxHashMap;
 use rustc_lint_defs::{Applicability, LintExpectationId};
 use rustc_serialize::json::Json;
 use rustc_span::edition::LATEST_STABLE_EDITION;
-use rustc_span::{MultiSpan, Span, DUMMY_SP};
+use rustc_span::{Span, DUMMY_SP};
 use std::fmt;
 use std::hash::{Hash, Hasher};
 
@@ -18,34 +16,6 @@ use std::hash::{Hash, Hasher};
 #[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
 pub struct SuggestionsDisabled;
 
-/// Abstraction over a message in a diagnostic to support both translatable and non-translatable
-/// diagnostic messages.
-#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
-pub enum DiagnosticMessage {
-    /// Non-translatable diagnostic message.
-    Str(String),
-    /// Identifier for a Fluent message corresponding to the diagnostic message.
-    FluentIdentifier(String),
-}
-
-impl DiagnosticMessage {
-    /// Convert `DiagnosticMessage` to a `&str`.
-    pub fn as_str(&self) -> &str {
-        match self {
-            DiagnosticMessage::Str(msg) => msg,
-            DiagnosticMessage::FluentIdentifier(..) => unimplemented!(),
-        }
-    }
-
-    /// Convert `DiagnosticMessage` to an owned `String`.
-    pub fn to_string(self) -> String {
-        match self {
-            DiagnosticMessage::Str(msg) => msg,
-            DiagnosticMessage::FluentIdentifier(..) => unimplemented!(),
-        }
-    }
-}
-
 #[must_use]
 #[derive(Clone, Debug, Encodable, Decodable)]
 pub struct Diagnostic {
@@ -262,7 +232,7 @@ impl Diagnostic {
         self.set_span(after);
         for span_label in before.span_labels() {
             if let Some(label) = span_label.label {
-                self.span_label(after, label);
+                self.span.push_span_message(after, label);
             }
         }
         self

compiler/rustc_errors/src/diagnostic_builder.rs

@@ -1,8 +1,8 @@
 use crate::{Diagnostic, DiagnosticId, DiagnosticStyledString, ErrorGuaranteed};
-use crate::{Handler, Level, StashKey};
+use crate::{Handler, Level, MultiSpan, StashKey};
 use rustc_lint_defs::Applicability;
 
-use rustc_span::{MultiSpan, Span};
+use rustc_span::Span;
 use std::fmt::{self, Debug};
 use std::marker::PhantomData;
 use std::ops::{Deref, DerefMut};

compiler/rustc_errors/src/emitter.rs

@@ -10,13 +10,13 @@
 use Destination::*;
 
 use rustc_span::source_map::SourceMap;
-use rustc_span::{MultiSpan, SourceFile, Span};
+use rustc_span::{SourceFile, Span};
 
 use crate::snippet::{Annotation, AnnotationType, Line, MultilineAnnotation, Style, StyledString};
 use crate::styled_buffer::StyledBuffer;
 use crate::{
-    CodeSuggestion, Diagnostic, DiagnosticId, DiagnosticMessage, Handler, Level, SubDiagnostic,
-    SubstitutionHighlight, SuggestionStyle,
+    CodeSuggestion, Diagnostic, DiagnosticId, DiagnosticMessage, Handler, Level, MultiSpan,
+    SubDiagnostic, SubstitutionHighlight, SuggestionStyle,
 };
 
 use rustc_lint_defs::pluralize;
@@ -2003,7 +2003,7 @@ impl FileWithAnnotatedLines {
                         start_col: lo.col_display,
                         end_col: hi.col_display,
                         is_primary: span_label.is_primary,
-                        label: span_label.label,
+                        label: span_label.label.map(|m| m.to_string()),
                         overlaps_exactly: false,
                     };
                     multiline_annotations.push((lo.file, ml));
@@ -2012,7 +2012,7 @@ impl FileWithAnnotatedLines {
                         start_col: lo.col_display,
                         end_col: hi.col_display,
                         is_primary: span_label.is_primary,
-                        label: span_label.label,
+                        label: span_label.label.map(|m| m.to_string()),
                         annotation_type: AnnotationType::Singleline,
                     };
                     add_annotation_to_file(&mut output, lo.file, lo.line, ann);

compiler/rustc_errors/src/json.rs

@@ -15,12 +15,12 @@ use crate::emitter::{Emitter, HumanReadableErrorType};
 use crate::registry::Registry;
 use crate::DiagnosticId;
 use crate::ToolMetadata;
-use crate::{CodeSuggestion, SubDiagnostic};
+use crate::{CodeSuggestion, MultiSpan, SpanLabel, SubDiagnostic};
 use rustc_lint_defs::Applicability;
 
 use rustc_data_structures::sync::Lrc;
 use rustc_span::hygiene::ExpnData;
-use rustc_span::{MultiSpan, Span, SpanLabel};
+use rustc_span::Span;
 use std::io::{self, Write};
 use std::path::Path;
 use std::sync::{Arc, Mutex};
@@ -423,7 +423,13 @@ impl DiagnosticSpan {
         suggestion: Option<(&String, Applicability)>,
         je: &JsonEmitter,
     ) -> DiagnosticSpan {
-        Self::from_span_etc(span.span, span.is_primary, span.label, suggestion, je)
+        Self::from_span_etc(
+            span.span,
+            span.is_primary,
+            span.label.map(|m| m.to_string()),
+            suggestion,
+            je,
+        )
     }
 
     fn from_span_etc(

compiler/rustc_errors/src/lib.rs

@@ -31,11 +31,12 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
 use rustc_data_structures::stable_hasher::StableHasher;
 use rustc_data_structures::sync::{self, Lock, Lrc};
 use rustc_data_structures::AtomicRef;
+pub use rustc_error_messages::{DiagnosticMessage, MultiSpan, SpanLabel};
 pub use rustc_lint_defs::{pluralize, Applicability};
 use rustc_serialize::json::Json;
 use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
 use rustc_span::source_map::SourceMap;
-use rustc_span::{Loc, MultiSpan, Span};
+use rustc_span::{Loc, Span};
 
 use std::borrow::Cow;
 use std::hash::{Hash, Hasher};
@@ -55,6 +56,7 @@ mod lock;
 pub mod registry;
 mod snippet;
 mod styled_buffer;
+
 pub use snippet::Style;
 
 pub type PResult<'a, T> = Result<T, DiagnosticBuilder<'a, ErrorGuaranteed>>;
@@ -400,9 +402,7 @@ impl fmt::Display for ExplicitBug {
 
 impl error::Error for ExplicitBug {}
 
-pub use diagnostic::{
-    Diagnostic, DiagnosticId, DiagnosticMessage, DiagnosticStyledString, SubDiagnostic,
-};
+pub use diagnostic::{Diagnostic, DiagnosticId, DiagnosticStyledString, SubDiagnostic};
 pub use diagnostic_builder::{DiagnosticBuilder, EmissionGuarantee};
 use std::backtrace::Backtrace;