Rollup merge of #98869 - compiler-errors:stop_guessing_head_span, r=cjgillot

Remove some usages of `guess_head_span`

No need to pass things through `guess_head_span` if they already point to the head span.

Only major change is that we point to the head span of `enum`s on some errors now, which I prefer.

r? `@cjgillot`

Author: Dylan-DPC

compiler/rustc_infer/src/infer/canonical/query_response.rs

@@ -714,10 +714,7 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
     }
 
     fn const_equate(&mut self, _a: Const<'tcx>, _b: Const<'tcx>) {
-        span_bug!(
-            self.cause.span(self.infcx.tcx),
-            "generic_const_exprs: unreachable `const_equate`"
-        );
+        span_bug!(self.cause.span(), "generic_const_exprs: unreachable `const_equate`");
     }
 
     fn normalization() -> NormalizationStrategy {

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1435,7 +1435,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         swap_secondary_and_primary: bool,
         force_label: bool,
     ) {
-        let span = cause.span(self.tcx);
+        let span = cause.span();
 
         // For some types of errors, expected-found does not make
         // sense, so just ignore the values we were given.
@@ -2085,7 +2085,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
         debug!("report_and_explain_type_error(trace={:?}, terr={:?})", trace, terr);
 
-        let span = trace.cause.span(self.tcx);
+        let span = trace.cause.span();
         let failure_code = trace.cause.as_failure_code(terr);
         let mut diag = match failure_code {
             FailureCode::Error0038(did) => {

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs

@@ -204,7 +204,7 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         expected_substs: SubstsRef<'tcx>,
         actual_substs: SubstsRef<'tcx>,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        let span = cause.span(self.tcx());
+        let span = cause.span();
         let msg = format!(
             "implementation of `{}` is not general enough",
             self.tcx().def_path_str(trait_def_id),

compiler/rustc_infer/src/traits/error_reporting/mod.rs

@@ -18,20 +18,19 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         trait_item_def_id: DefId,
         requirement: &dyn fmt::Display,
     ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
-        let msg = "impl has stricter requirements than trait";
-        let sp = self.tcx.sess.source_map().guess_head_span(error_span);
+        let mut err = struct_span_err!(
+            self.tcx.sess,
+            error_span,
+            E0276,
+            "impl has stricter requirements than trait"
+        );
 
-        let mut err = struct_span_err!(self.tcx.sess, sp, E0276, "{}", msg);
-
-        if trait_item_def_id.is_local() {
+        if let Some(span) = self.tcx.hir().span_if_local(trait_item_def_id) {
             let item_name = self.tcx.item_name(impl_item_def_id.to_def_id());
-            err.span_label(
-                self.tcx.def_span(trait_item_def_id),
-                format!("definition of `{}` from trait", item_name),
-            );
+            err.span_label(span, format!("definition of `{}` from trait", item_name));
         }
 
-        err.span_label(sp, format!("impl has extra requirement {}", requirement));
+        err.span_label(error_span, format!("impl has extra requirement {}", requirement));
 
         err
     }
@@ -48,7 +47,6 @@ pub fn report_object_safety_error<'tcx>(
         hir::Node::Item(item) => Some(item.ident.span),
         _ => None,
     });
-    let span = tcx.sess.source_map().guess_head_span(span);
     let mut err = struct_span_err!(
         tcx.sess,
         span,

compiler/rustc_lint/src/context.rs

@@ -694,9 +694,8 @@ pub trait LintContext: Sized {
                     }
 
                     if let Some(span) = in_test_module {
-                        let def_span = self.sess().source_map().guess_head_span(span);
                         db.span_help(
-                            span.shrink_to_lo().to(def_span),
+                            self.sess().source_map().guess_head_span(span),
                             "consider adding a `#[cfg(test)]` to the containing module",
                         );
                     }

compiler/rustc_middle/src/traits/mod.rs

@@ -139,13 +139,8 @@ impl<'tcx> ObligationCause<'tcx> {
         ObligationCause { span, body_id: hir::CRATE_HIR_ID, code: Default::default() }
     }
 
-    pub fn span(&self, tcx: TyCtxt<'tcx>) -> Span {
+    pub fn span(&self) -> Span {
         match *self.code() {
-            ObligationCauseCode::CompareImplMethodObligation { .. }
-            | ObligationCauseCode::MainFunctionType
-            | ObligationCauseCode::StartFunctionType => {
-                tcx.sess.source_map().guess_head_span(self.span)
-            }
             ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
                 arm_span,
                 ..

compiler/rustc_privacy/src/lib.rs

@@ -1759,8 +1759,7 @@ impl SearchInterfaceForPrivateItemsVisitor<'_> {
                 || self.tcx.resolutions(()).has_pub_restricted
             {
                 let descr = descr.to_string();
-                let vis_span =
-                    self.tcx.sess.source_map().guess_head_span(self.tcx.def_span(def_id));
+                let vis_span = self.tcx.def_span(def_id);
                 if kind == "trait" {
                     self.tcx.sess.emit_err(InPublicInterfaceTraits {
                         span,

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -823,10 +823,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
 
                     ty::PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
                         let found_kind = self.closure_kind(closure_substs).unwrap();
-                        let closure_span =
-                            self.tcx.sess.source_map().guess_head_span(
-                                self.tcx.hir().span_if_local(closure_def_id).unwrap(),
-                            );
+                        let closure_span = self.tcx.def_span(closure_def_id);
                         let mut err = struct_span_err!(
                             self.tcx.sess,
                             closure_span,
@@ -951,9 +948,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                     _ => None,
                 };
 
-                let found_span = found_did
-                    .and_then(|did| self.tcx.hir().span_if_local(did))
-                    .map(|sp| self.tcx.sess.source_map().guess_head_span(sp)); // the sp could be an fn def
+                let found_span = found_did.and_then(|did| self.tcx.hir().span_if_local(did));
 
                 if self.reported_closure_mismatch.borrow().contains(&(span, found_span)) {
                     // We check closures twice, with obligations flowing in different directions,
@@ -1089,7 +1084,7 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
                 kind: hir::ExprKind::Closure(&hir::Closure { body, fn_decl_span, .. }),
                 ..
             }) => (
-                sm.guess_head_span(fn_decl_span),
+                fn_decl_span,
                 hir.body(body)
                     .params
                     .iter()

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -1543,7 +1543,6 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
             ty::Generator(..) => "generator",
             _ => "function",
         };
-        let span = self.tcx.sess.source_map().guess_head_span(span);
         let mut err = struct_span_err!(
             self.tcx.sess,
             span,

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -603,7 +603,7 @@ impl<'a, 'b, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'b, 'tcx> {
                         ),
                         (Err(ErrorHandled::Linted), _) | (_, Err(ErrorHandled::Linted)) => {
                             span_bug!(
-                                obligation.cause.span(self.selcx.tcx()),
+                                obligation.cause.span(),
                                 "ConstEquate: const_eval_resolve returned an unexpected error"
                             )
                         }