improve early lint to use multispan from diagnostic

src/librustc/lint/context.rs

@@ -83,15 +83,11 @@ pub struct LintStore {
 
 /// When you call `add_lint` on the session, you wind up storing one
 /// of these, which records a "potential lint" at a particular point.
+#[derive(PartialEq)]
 pub struct EarlyLint {
     /// what lint is this? (e.g., `dead_code`)
     pub id: LintId,
 
-    /// what span was it attached to (this is used for Eq comparisons;
-    /// it duplicates to some extent the information in
-    /// `diagnostic.span`)
-    pub span: MultiSpan,
-
     /// the main message
     pub diagnostic: Diagnostic,
 }
@@ -106,38 +102,22 @@ impl fmt::Debug for EarlyLint {
     }
 }
 
-impl EarlyLint {
-    pub fn new<M: EarlyLintMessage>(id: LintId, span: Span, msg: M) -> Self {
-        let diagnostic = msg.into_diagnostic(span);
-        EarlyLint { id: id, span: MultiSpan::from(span), diagnostic: diagnostic }
-    }
-
-    pub fn with_diagnostic(id: LintId, span: Span, diagnostic: Diagnostic) -> Self {
-        EarlyLint { id: id, span: MultiSpan::from(span), diagnostic: diagnostic }
-    }
-
-    pub fn matches(&self, other: &EarlyLint) -> bool {
-        self.id == other.id &&
-            self.span == other.span &&
-            self.diagnostic.message == other.diagnostic.message
-    }
+pub trait IntoEarlyLint {
+    fn into_early_lint(self, id: LintId) -> EarlyLint;
 }
 
-pub trait EarlyLintMessage {
-    fn into_diagnostic(self, span: Span) -> Diagnostic;
-}
-
-impl EarlyLintMessage for String {
-    fn into_diagnostic(self, span: Span) -> Diagnostic {
-        let mut diagnostic = Diagnostic::new(errors::Level::Warning, &self);
+impl<'a> IntoEarlyLint for (Span, &'a str) {
+    fn into_early_lint(self, id: LintId) -> EarlyLint {
+        let (span, msg) = self;
+        let mut diagnostic = Diagnostic::new(errors::Level::Warning, msg);
         diagnostic.set_span(span);
-        diagnostic
+        EarlyLint { id: id, diagnostic: diagnostic }
     }
 }
 
-impl EarlyLintMessage for Diagnostic {
-    fn into_diagnostic(self, _span: Span) -> Diagnostic {
-        self
+impl IntoEarlyLint for Diagnostic {
+    fn into_early_lint(self, id: LintId) -> EarlyLint {
+        EarlyLint { id: id, diagnostic: self }
     }
 }
 
@@ -578,8 +558,9 @@ pub trait LintContext: Sized {
     }
 
     fn early_lint(&self, early_lint: EarlyLint) {
+        let span = early_lint.diagnostic.span.primary_span().expect("early lint w/o primary span");
         let mut err = self.struct_span_lint(early_lint.id.lint,
-                                            early_lint.span,
+                                            span,
                                             &early_lint.diagnostic.message);
         err.copy_details_not_message(&early_lint.diagnostic);
         err.emit();
@@ -1283,7 +1264,7 @@ pub fn check_crate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
     // in the iteration code.
     for (id, v) in tcx.sess.lints.borrow().iter() {
         for early_lint in v {
-            span_bug!(early_lint.span.clone(),
+            span_bug!(early_lint.diagnostic.span.clone(),
                       "unprocessed lint {:?} at {}",
                       early_lint, tcx.map.node_to_string(*id));
         }
@@ -1321,7 +1302,7 @@ pub fn check_ast_crate(sess: &Session, krate: &ast::Crate) {
     // in the iteration code.
     for (_, v) in sess.lints.borrow().iter() {
         for early_lint in v {
-            span_bug!(early_lint.span.clone(), "unprocessed lint {:?}", early_lint);
+            span_bug!(early_lint.diagnostic.span.clone(), "unprocessed lint {:?}", early_lint);
         }
     }
 }

src/librustc/lint/mod.rs

@@ -41,7 +41,7 @@ use hir;
 
 pub use lint::context::{LateContext, EarlyContext, LintContext, LintStore,
                         raw_emit_lint, check_crate, check_ast_crate, gather_attrs,
-                        raw_struct_lint, FutureIncompatibleInfo, EarlyLint, EarlyLintMessage};
+                        raw_struct_lint, FutureIncompatibleInfo, EarlyLint, IntoEarlyLint};
 
 /// Specification of a single lint.
 #[derive(Copy, Clone, Debug)]

src/librustc/session/mod.rs

@@ -258,16 +258,25 @@ impl Session {
     pub fn unimpl(&self, msg: &str) -> ! {
         self.diagnostic().unimpl(msg)
     }
-    pub fn add_lint<M: lint::EarlyLintMessage>(&self,
-                                               lint: &'static lint::Lint,
-                                               id: ast::NodeId,
-                                               sp: Span,
-                                               msg: M) {
+    pub fn add_lint(&self,
+                    lint: &'static lint::Lint,
+                    id: ast::NodeId,
+                    sp: Span,
+                    msg: String)
+    {
+        self.add_lint_diagnostic(lint, id, (sp, &msg[..]))
+    }
+    pub fn add_lint_diagnostic<M>(&self,
+                                  lint: &'static lint::Lint,
+                                  id: ast::NodeId,
+                                  msg: M)
+        where M: lint::IntoEarlyLint,
+    {
         let lint_id = lint::LintId::of(lint);
         let mut lints = self.lints.borrow_mut();
-        let early_lint = lint::EarlyLint::new(lint_id, sp, msg);
+        let early_lint = msg.into_early_lint(lint_id);
         if let Some(arr) = lints.get_mut(&id) {
-            if !arr.iter().any(|l| l.matches(&early_lint)) {
+            if !arr.contains(&early_lint) {
                 arr.push(early_lint);
             }
             return;

src/librustc_errors/diagnostic.rs

@@ -6,7 +6,7 @@ use std::fmt;
 use syntax_pos::{MultiSpan, Span};
 
 #[must_use]
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub struct Diagnostic {
     pub level: Level,
     pub message: String,
@@ -16,7 +16,7 @@ pub struct Diagnostic {
 }
 
 /// For example a note attached to an error.
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub struct SubDiagnostic {
     pub level: Level,
     pub message: String,

src/librustc_errors/lib.rs

@@ -57,7 +57,7 @@ mod lock;
 use syntax_pos::{BytePos, Loc, FileLinesResult, FileName, MultiSpan, Span, NO_EXPANSION};
 use syntax_pos::MacroBacktrace;
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum RenderSpan {
     /// A FullSpan renders with both with an initial line for the
     /// message, prefixed by file:linenum, followed by a summary of
@@ -71,7 +71,7 @@ pub enum RenderSpan {
     Suggestion(CodeSuggestion),
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub struct CodeSuggestion {
     pub msp: MultiSpan,
     pub substitutes: Vec<String>,