Rework rustc_serialize

- Move the type parameter from `encode` and `decode` methods to
  the trait.
- Remove `UseSpecialized(En|De)codable` traits.
- Remove blanket impls for references.
- Add `RefDecodable` trait to allow deserializing to arena-allocated
  references safely.
- Remove ability to (de)serialize HIR.
- Create proc-macros `(Ty)?(En|De)codable` to help implement these new
  traits.

src/librustc_errors/Cargo.toml

@@ -13,6 +13,7 @@ doctest = false
 log = { package = "tracing", version = "0.1" }
 rustc_serialize = { path = "../librustc_serialize" }
 rustc_span = { path = "../librustc_span" }
+rustc_macros = { path = "../librustc_macros" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 unicode-width = "0.1.4"
 atty = "0.2"

src/librustc_errors/diagnostic.rs

@@ -9,7 +9,7 @@ use rustc_span::{MultiSpan, Span, DUMMY_SP};
 use std::fmt;
 
 #[must_use]
-#[derive(Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub struct Diagnostic {
     pub level: Level,
     pub message: Vec<(String, Style)>,
@@ -24,14 +24,14 @@ pub struct Diagnostic {
     pub sort_span: Span,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, PartialEq, Eq, Hash, Encodable, Decodable)]
 pub enum DiagnosticId {
     Error(String),
     Lint(String),
 }
 
 /// For example a note attached to an error.
-#[derive(Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub struct SubDiagnostic {
     pub level: Level,
     pub message: Vec<(String, Style)>,

src/librustc_errors/json.rs

@@ -145,7 +145,7 @@ impl Emitter for JsonEmitter {
 
 // The following data types are provided just for serialisation.
 
-#[derive(RustcEncodable)]
+#[derive(Encodable)]
 struct Diagnostic {
     /// The primary error message.
     message: String,
@@ -159,7 +159,7 @@ struct Diagnostic {
     rendered: Option<String>,
 }
 
-#[derive(RustcEncodable)]
+#[derive(Encodable)]
 struct DiagnosticSpan {
     file_name: String,
     byte_start: u32,
@@ -186,7 +186,7 @@ struct DiagnosticSpan {
     expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
 }
 
-#[derive(RustcEncodable)]
+#[derive(Encodable)]
 struct DiagnosticSpanLine {
     text: String,
 
@@ -196,7 +196,7 @@ struct DiagnosticSpanLine {
     highlight_end: usize,
 }
 
-#[derive(RustcEncodable)]
+#[derive(Encodable)]
 struct DiagnosticSpanMacroExpansion {
     /// span where macro was applied to generate this code; note that
     /// this may itself derive from a macro (if
@@ -210,7 +210,7 @@ struct DiagnosticSpanMacroExpansion {
     def_site_span: DiagnosticSpan,
 }
 
-#[derive(RustcEncodable)]
+#[derive(Encodable)]
 struct DiagnosticCode {
     /// The code itself.
     code: String,
@@ -218,7 +218,7 @@ struct DiagnosticCode {
     explanation: Option<&'static str>,
 }
 
-#[derive(RustcEncodable)]
+#[derive(Encodable)]
 struct ArtifactNotification<'a> {
     /// The path of the artifact.
     artifact: &'a Path,

src/librustc_errors/json/tests.rs

@@ -10,12 +10,12 @@ use rustc_span::{BytePos, Span};
 
 use std::str;
 
-#[derive(RustcDecodable, Debug, PartialEq, Eq)]
+#[derive(Decodable, Debug, PartialEq, Eq)]
 struct TestData {
     spans: Vec<SpanTestData>,
 }
 
-#[derive(RustcDecodable, Debug, PartialEq, Eq)]
+#[derive(Decodable, Debug, PartialEq, Eq)]
 struct SpanTestData {
     pub byte_start: u32,
     pub byte_end: u32,

src/librustc_errors/lib.rs

@@ -6,6 +6,9 @@
 #![feature(crate_visibility_modifier)]
 #![feature(nll)]
 
+#[macro_use]
+extern crate rustc_macros;
+
 pub use emitter::ColorConfig;
 
 use log::debug;
@@ -50,7 +53,7 @@ rustc_data_structures::static_assert_size!(PResult<'_, bool>, 16);
 /// All suggestions are marked with an `Applicability`. Tools use the applicability of a suggestion
 /// to determine whether it should be automatically applied or if the user should be consulted
 /// before applying the suggestion.
-#[derive(Copy, Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub enum Applicability {
     /// The suggestion is definitely what the user intended. This suggestion should be
     /// automatically applied.
@@ -69,7 +72,7 @@ pub enum Applicability {
     Unspecified,
 }
 
-#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Hash, Encodable, Decodable)]
 pub enum SuggestionStyle {
     /// Hide the suggested code when displaying this suggestion inline.
     HideCodeInline,
@@ -94,7 +97,7 @@ impl SuggestionStyle {
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub struct CodeSuggestion {
     /// Each substitute can have multiple variants due to multiple
     /// applicable suggestions
@@ -129,13 +132,13 @@ pub struct CodeSuggestion {
     pub applicability: Applicability,
 }
 
-#[derive(Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 /// See the docs on `CodeSuggestion::substitutions`
 pub struct Substitution {
     pub parts: Vec<SubstitutionPart>,
 }
 
-#[derive(Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub struct SubstitutionPart {
     pub span: Span,
     pub snippet: String,
@@ -943,7 +946,7 @@ impl HandlerInner {
     }
 }
 
-#[derive(Copy, PartialEq, Clone, Hash, Debug, RustcEncodable, RustcDecodable)]
+#[derive(Copy, PartialEq, Clone, Hash, Debug, Encodable, Decodable)]
 pub enum Level {
     Bug,
     Fatal,
@@ -1012,7 +1015,7 @@ macro_rules! pluralize {
 
 // Useful type to use with `Result<>` indicate that an error has already
 // been reported to the user, so no need to continue checking.
-#[derive(Clone, Copy, Debug, RustcEncodable, RustcDecodable, Hash, PartialEq, Eq)]
+#[derive(Clone, Copy, Debug, Encodable, Decodable, Hash, PartialEq, Eq)]
 pub struct ErrorReported;
 
 rustc_data_structures::impl_stable_hash_via_hash!(ErrorReported);

src/librustc_errors/snippet.rs

@@ -173,7 +173,7 @@ pub struct StyledString {
     pub style: Style,
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Hash, RustcEncodable, RustcDecodable)]
+#[derive(Copy, Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
 pub enum Style {
     MainHeaderMsg,
     HeaderMsg,