Rename def_span to guess_head_span

src/librustc/traits/mod.rs

@@ -108,7 +108,9 @@ impl<'tcx> ObligationCause<'tcx> {
         match self.code {
             ObligationCauseCode::CompareImplMethodObligation { .. }
             | ObligationCauseCode::MainFunctionType
-            | ObligationCauseCode::StartFunctionType => tcx.sess.source_map().def_span(self.span),
+            | ObligationCauseCode::StartFunctionType => {
+                tcx.sess.source_map().guess_head_span(self.span)
+            }
             ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
                 arm_span,
                 ..

src/librustc/ty/query/plumbing.rs

@@ -388,7 +388,7 @@ impl<'tcx> TyCtxt<'tcx> {
         assert!(!stack.is_empty());
 
         let fix_span = |span: Span, query: &Query<'tcx>| {
-            self.sess.source_map().def_span(query.default_span(self, span))
+            self.sess.source_map().guess_head_span(query.default_span(self, span))
         };
 
         // Disable naming impls with types in this path, since that
@@ -456,7 +456,8 @@ impl<'tcx> TyCtxt<'tcx> {
                             query_info.info.query.describe(icx.tcx)
                         ),
                     );
-                    diag.span = icx.tcx.sess.source_map().def_span(query_info.info.span).into();
+                    diag.span =
+                        icx.tcx.sess.source_map().guess_head_span(query_info.info.span).into();
                     handler.force_print_diagnostic(diag);
 
                     current_query = query_info.job.parent;

src/librustc_ast_passes/ast_validation.rs

@@ -402,7 +402,7 @@ impl<'a> AstValidator<'a> {
 
     fn check_defaultness(&self, span: Span, defaultness: Defaultness) {
         if let Defaultness::Default(def_span) = defaultness {
-            let span = self.session.source_map().def_span(span);
+            let span = self.session.source_map().guess_head_span(span);
             self.err_handler()
                 .struct_span_err(span, "`default` is only allowed on items in `impl` definitions")
                 .span_label(def_span, "`default` because of this")
@@ -517,7 +517,7 @@ impl<'a> AstValidator<'a> {
     }
 
     fn current_extern_span(&self) -> Span {
-        self.session.source_map().def_span(self.extern_mod.unwrap().span)
+        self.session.source_map().guess_head_span(self.extern_mod.unwrap().span)
     }
 
     /// An `fn` in `extern { ... }` cannot have qualfiers, e.g. `async fn`.

src/librustc_ast_passes/feature_gate.rs

@@ -257,7 +257,7 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             gate_feature_post!(
                 &self,
                 non_ascii_idents,
-                self.parse_sess.source_map().def_span(sp),
+                self.parse_sess.source_map().guess_head_span(sp),
                 "non-ascii idents are not fully supported"
             );
         }

src/librustc_builtin_macros/proc_macro_harness.rs

@@ -198,7 +198,7 @@ impl<'a> CollectProcMacros<'a> {
             } else {
                 "functions tagged with `#[proc_macro_derive]` must be `pub`"
             };
-            self.handler.span_err(self.source_map.def_span(item.span), msg);
+            self.handler.span_err(self.source_map.guess_head_span(item.span), msg);
         }
     }
 
@@ -217,7 +217,7 @@ impl<'a> CollectProcMacros<'a> {
             } else {
                 "functions tagged with `#[proc_macro_attribute]` must be `pub`"
             };
-            self.handler.span_err(self.source_map.def_span(item.span), msg);
+            self.handler.span_err(self.source_map.guess_head_span(item.span), msg);
         }
     }
 
@@ -236,7 +236,7 @@ impl<'a> CollectProcMacros<'a> {
             } else {
                 "functions tagged with `#[proc_macro]` must be `pub`"
             };
-            self.handler.span_err(self.source_map.def_span(item.span), msg);
+            self.handler.span_err(self.source_map.guess_head_span(item.span), msg);
         }
     }
 }
@@ -247,7 +247,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
             if self.is_proc_macro_crate && attr::contains_name(&item.attrs, sym::macro_export) {
                 let msg =
                     "cannot export macro_rules! macros from a `proc-macro` crate type currently";
-                self.handler.span_err(self.source_map.def_span(item.span), msg);
+                self.handler.span_err(self.source_map.guess_head_span(item.span), msg);
             }
         }
 
@@ -298,7 +298,7 @@ impl<'a> Visitor<'a> for CollectProcMacros<'a> {
 
         let attr = match found_attr {
             None => {
-                self.check_not_pub_in_root(&item.vis, self.source_map.def_span(item.span));
+                self.check_not_pub_in_root(&item.vis, self.source_map.guess_head_span(item.span));
                 let prev_in_root = mem::replace(&mut self.in_root, false);
                 visit::walk_item(self, item);
                 self.in_root = prev_in_root;

src/librustc_expand/mbe/macro_rules.rs

@@ -326,7 +326,7 @@ fn generic_extension<'cx>(
     let mut err = cx.struct_span_err(span, &parse_failure_msg(&token));
     err.span_label(span, label);
     if !def_span.is_dummy() && !cx.source_map().is_imported(def_span) {
-        err.span_label(cx.source_map().def_span(def_span), "when calling this macro");
+        err.span_label(cx.source_map().guess_head_span(def_span), "when calling this macro");
     }
 
     // Check whether there's a missing comma in this macro call, like `println!("{}" a);`

src/librustc_infer/infer/error_reporting/mod.rs

@@ -200,7 +200,7 @@ fn msg_span_from_early_bound_and_free_regions(
     };
     let (prefix, span) = match *region {
         ty::ReEarlyBound(ref br) => {
-            let mut sp = sm.def_span(tcx.hir().span(node));
+            let mut sp = sm.guess_head_span(tcx.hir().span(node));
             if let Some(param) =
                 tcx.hir().get_generics(scope).and_then(|generics| generics.get_named(br.name))
             {
@@ -209,7 +209,7 @@ fn msg_span_from_early_bound_and_free_regions(
             (format!("the lifetime `{}` as defined on", br.name), sp)
         }
         ty::ReFree(ty::FreeRegion { bound_region: ty::BoundRegion::BrNamed(_, name), .. }) => {
-            let mut sp = sm.def_span(tcx.hir().span(node));
+            let mut sp = sm.guess_head_span(tcx.hir().span(node));
             if let Some(param) =
                 tcx.hir().get_generics(scope).and_then(|generics| generics.get_named(name))
             {
@@ -223,7 +223,7 @@ fn msg_span_from_early_bound_and_free_regions(
             }
             _ => (
                 format!("the lifetime `{}` as defined on", region),
-                sm.def_span(tcx.hir().span(node)),
+                sm.guess_head_span(tcx.hir().span(node)),
             ),
         },
         _ => bug!(),

src/librustc_infer/traits/error_reporting/mod.rs

@@ -20,12 +20,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         requirement: &dyn fmt::Display,
     ) -> DiagnosticBuilder<'tcx> {
         let msg = "impl has stricter requirements than trait";
-        let sp = self.tcx.sess.source_map().def_span(error_span);
+        let sp = self.tcx.sess.source_map().guess_head_span(error_span);
 
         let mut err = struct_span_err!(self.tcx.sess, sp, E0276, "{}", msg);
 
         if let Some(trait_item_span) = self.tcx.hir().span_if_local(trait_item_def_id) {
-            let span = self.tcx.sess.source_map().def_span(trait_item_span);
+            let span = self.tcx.sess.source_map().guess_head_span(trait_item_span);
             err.span_label(span, format!("definition of `{}` from trait", item_name));
         }
 
@@ -46,7 +46,7 @@ pub fn report_object_safety_error(
         hir::Node::Item(item) => Some(item.ident.span),
         _ => None,
     });
-    let span = tcx.sess.source_map().def_span(span);
+    let span = tcx.sess.source_map().guess_head_span(span);
     let mut err = struct_span_err!(
         tcx.sess,
         span,

src/librustc_lint/builtin.rs

@@ -76,7 +76,7 @@ impl EarlyLintPass for WhileTrue {
                 if let ast::LitKind::Bool(true) = lit.kind {
                     if !lit.span.from_expansion() {
                         let msg = "denote infinite loops with `loop { ... }`";
-                        let condition_span = cx.sess.source_map().def_span(e.span);
+                        let condition_span = cx.sess.source_map().guess_head_span(e.span);
                         cx.struct_span_lint(WHILE_TRUE, condition_span, |lint| {
                             lint.build(msg)
                                 .span_suggestion_short(
@@ -374,9 +374,13 @@ impl MissingDoc {
 
         let has_doc = attrs.iter().any(|a| has_doc(a));
         if !has_doc {
-            cx.struct_span_lint(MISSING_DOCS, cx.tcx.sess.source_map().def_span(sp), |lint| {
-                lint.build(&format!("missing documentation for {} {}", article, desc)).emit()
-            });
+            cx.struct_span_lint(
+                MISSING_DOCS,
+                cx.tcx.sess.source_map().guess_head_span(sp),
+                |lint| {
+                    lint.build(&format!("missing documentation for {} {}", article, desc)).emit()
+                },
+            );
         }
     }
 }
@@ -406,7 +410,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MissingDoc {
             if !has_doc {
                 cx.struct_span_lint(
                     MISSING_DOCS,
-                    cx.tcx.sess.source_map().def_span(macro_def.span),
+                    cx.tcx.sess.source_map().guess_head_span(macro_def.span),
                     |lint| lint.build("missing documentation for macro").emit(),
                 );
             }
@@ -978,7 +982,7 @@ impl UnreachablePub {
                 if span.from_expansion() {
                     applicability = Applicability::MaybeIncorrect;
                 }
-                let def_span = cx.tcx.sess.source_map().def_span(span);
+                let def_span = cx.tcx.sess.source_map().guess_head_span(span);
                 cx.struct_span_lint(UNREACHABLE_PUB, def_span, |lint| {
                     let mut err = lint.build(&format!("unreachable `pub` {}", what));
                     let replacement = if cx.tcx.features().crate_visibility_modifier {

src/librustc_mir/transform/check_unsafety.rs

@@ -565,14 +565,14 @@ fn is_enclosed(
 }
 
 fn report_unused_unsafe(tcx: TyCtxt<'_>, used_unsafe: &FxHashSet<hir::HirId>, id: hir::HirId) {
-    let span = tcx.sess.source_map().def_span(tcx.hir().span(id));
+    let span = tcx.sess.source_map().guess_head_span(tcx.hir().span(id));
     tcx.struct_span_lint_hir(UNUSED_UNSAFE, id, span, |lint| {
         let msg = "unnecessary `unsafe` block";
         let mut db = lint.build(msg);
         db.span_label(span, msg);
         if let Some((kind, id)) = is_enclosed(tcx, used_unsafe, id) {
             db.span_label(
-                tcx.sess.source_map().def_span(tcx.hir().span(id)),
+                tcx.sess.source_map().guess_head_span(tcx.hir().span(id)),
                 format!("because it's nested under this `unsafe` {}", kind),
             );
         }

src/librustc_mir_build/lints.rs

@@ -123,7 +123,7 @@ fn check_fn_for_unconditional_recursion<'tcx>(
     // recurs.
     if !reached_exit_without_self_call && !self_call_locations.is_empty() {
         let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
-        let sp = tcx.sess.source_map().def_span(tcx.hir().span(hir_id));
+        let sp = tcx.sess.source_map().guess_head_span(tcx.hir().span(hir_id));
         tcx.struct_span_lint_hir(UNCONDITIONAL_RECURSION, hir_id, sp, |lint| {
             let mut db = lint.build("function cannot return without recursing");
             db.span_label(sp, "cannot return without recursing");

src/librustc_parse/parser/item.rs

@@ -907,7 +907,7 @@ impl<'a> Parser<'a> {
     }
 
     fn error_bad_item_kind<T>(&self, span: Span, kind: &ItemKind, ctx: &str) -> Option<T> {
-        let span = self.sess.source_map().def_span(span);
+        let span = self.sess.source_map().guess_head_span(span);
         let msg = format!("{} is not supported in {}", kind.descr(), ctx);
         self.struct_span_err(span, &msg).emit();
         None

src/librustc_passes/dead.rs

@@ -590,7 +590,7 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> {
                     // We should probably annotate ident.span with the macro
                     // context, but that's a larger change.
                     if item.span.source_callee().is_some() {
-                        self.tcx.sess.source_map().def_span(item.span)
+                        self.tcx.sess.source_map().guess_head_span(item.span)
                     } else {
                         item.ident.span
                     }
@@ -663,7 +663,7 @@ impl Visitor<'tcx> for DeadVisitor<'tcx> {
             }
             hir::ImplItemKind::Fn(_, body_id) => {
                 if !self.symbol_is_live(impl_item.hir_id) {
-                    let span = self.tcx.sess.source_map().def_span(impl_item.span);
+                    let span = self.tcx.sess.source_map().guess_head_span(impl_item.span);
                     self.warn_dead_code(
                         impl_item.hir_id,
                         span,

src/librustc_resolve/diagnostics.rs

@@ -791,12 +791,12 @@ impl<'a> Resolver<'a> {
                 _ => Some(
                     self.session
                         .source_map()
-                        .def_span(self.cstore().get_span_untracked(def_id, self.session)),
+                        .guess_head_span(self.cstore().get_span_untracked(def_id, self.session)),
                 ),
             });
             if let Some(span) = def_span {
                 err.span_label(
-                    self.session.source_map().def_span(span),
+                    self.session.source_map().guess_head_span(span),
                     &format!(
                         "similarly named {} `{}` defined here",
                         suggestion.res.descr(),
@@ -986,7 +986,7 @@ impl<'a> Resolver<'a> {
                 which = if first { "" } else { " which" },
                 dots = if next_binding.is_some() { "..." } else { "" },
             );
-            let def_span = self.session.source_map().def_span(binding.span);
+            let def_span = self.session.source_map().guess_head_span(binding.span);
             let mut note_span = MultiSpan::from_span(def_span);
             if !first && binding.vis == ty::Visibility::Public {
                 note_span.push_span_label(def_span, "consider importing it directly".into());

src/librustc_resolve/imports.rs

@@ -1441,7 +1441,7 @@ impl<'a, 'b> ImportResolver<'a, 'b> {
                     let enum_resolution = resolutions.get(&key).expect("resolution should exist");
                     let enum_span =
                         enum_resolution.borrow().binding.expect("binding should exist").span;
-                    let enum_def_span = this.session.source_map().def_span(enum_span);
+                    let enum_def_span = this.session.source_map().guess_head_span(enum_span);
                     let enum_def_snippet = this
                         .session
                         .source_map()

src/librustc_resolve/lib.rs

@@ -2517,7 +2517,8 @@ impl<'a> Resolver<'a> {
             false => "defined",
         };
 
-        let (name, span) = (ident.name, self.session.source_map().def_span(new_binding.span));
+        let (name, span) =
+            (ident.name, self.session.source_map().guess_head_span(new_binding.span));
 
         if let Some(s) = self.name_already_seen.get(&name) {
             if s == &span {
@@ -2558,7 +2559,7 @@ impl<'a> Resolver<'a> {
 
         err.span_label(span, format!("`{}` re{} here", name, new_participle));
         err.span_label(
-            self.session.source_map().def_span(old_binding.span),
+            self.session.source_map().guess_head_span(old_binding.span),
             format!("previous {} of the {} `{}` here", old_noun, old_kind, name),
         );
 

src/librustc_span/source_map.rs

@@ -733,7 +733,14 @@ impl SourceMap {
         }
     }
 
-    pub fn def_span(&self, sp: Span) -> Span {
+    /// Given a `Span`, return a span ending in the closest `{`. This is useful when you have a
+    /// `Span` enclosing a whole item but we need to point at only the head (usually the first
+    /// line) of that item.
+    ///
+    /// *Only suitable for diagnostics.*
+    pub fn guess_head_span(&self, sp: Span) -> Span {
+        // FIXME: extend the AST items to have a head span, or replace callers with pointing at
+        // the item's ident when appropriate.
         self.span_until_char(sp, '{')
     }
 

src/librustc_trait_selection/traits/error_reporting/mod.rs

@@ -482,11 +482,10 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 
                     ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
                         let found_kind = self.closure_kind(closure_substs).unwrap();
-                        let closure_span = self
-                            .tcx
-                            .sess
-                            .source_map()
-                            .def_span(self.tcx.hir().span_if_local(closure_def_id).unwrap());
+                        let closure_span =
+                            self.tcx.sess.source_map().guess_head_span(
+                                self.tcx.hir().span_if_local(closure_def_id).unwrap(),
+                            );
                         let hir_id = self.tcx.hir().as_local_hir_id(closure_def_id).unwrap();
                         let mut err = struct_span_err!(
                             self.tcx.sess,
@@ -580,7 +579,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 
                 let found_span = found_did
                     .and_then(|did| self.tcx.hir().span_if_local(did))
-                    .map(|sp| self.tcx.sess.source_map().def_span(sp)); // the sp could be an fn def
+                    .map(|sp| self.tcx.sess.source_map().guess_head_span(sp)); // the sp could be an fn def
 
                 if self.reported_closure_mismatch.borrow().contains(&(span, found_span)) {
                     // We check closures twice, with obligations flowing in different directions,
@@ -680,7 +679,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 kind: hir::ExprKind::Closure(_, ref _decl, id, span, _),
                 ..
             }) => (
-                self.tcx.sess.source_map().def_span(span),
+                self.tcx.sess.source_map().guess_head_span(span),
                 self.tcx
                     .hir()
                     .body(id)
@@ -723,7 +722,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 kind: hir::TraitItemKind::Fn(ref sig, _),
                 ..
             }) => (
-                self.tcx.sess.source_map().def_span(span),
+                self.tcx.sess.source_map().guess_head_span(span),
                 sig.decl
                     .inputs
                     .iter()
@@ -741,7 +740,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     .ctor_hir_id()
                     .map(|hir_id| self.tcx.hir().span(hir_id))
                     .unwrap_or(DUMMY_SP);
-                let span = self.tcx.sess.source_map().def_span(span);
+                let span = self.tcx.sess.source_map().guess_head_span(span);
 
                 (span, vec![ArgKind::empty(); variant_data.fields().len()])
             }
@@ -1624,7 +1623,7 @@ pub fn recursive_type_with_infinite_size_error(
 ) -> DiagnosticBuilder<'tcx> {
     assert!(type_def_id.is_local());
     let span = tcx.hir().span_if_local(type_def_id).unwrap();
-    let span = tcx.sess.source_map().def_span(span);
+    let span = tcx.sess.source_map().guess_head_span(span);
     let mut err = struct_span_err!(
         tcx.sess,
         span,

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

@@ -1381,7 +1381,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 let msg = format!("required by `{}`", item_name);
 
                 if let Some(sp) = tcx.hir().span_if_local(item_def_id) {
-                    let sp = tcx.sess.source_map().def_span(sp);
+                    let sp = tcx.sess.source_map().guess_head_span(sp);
                     err.span_label(sp, &msg);
                 } else {
                     err.note(&msg);