Rollup merge of rust-lang#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"
                             )
                         }

compiler/rustc_trait_selection/src/traits/query/evaluate_obligation.rs

@@ -84,7 +84,7 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'cx, 'tcx> {
         // Run canonical query. If overflow occurs, rerun from scratch but this time
         // in standard trait query mode so that overflow is handled appropriately
         // within `SelectionContext`.
-        self.tcx.at(obligation.cause.span(self.tcx)).evaluate_obligation(c_pred)
+        self.tcx.at(obligation.cause.span()).evaluate_obligation(c_pred)
     }
 
     // Helper function that canonicalizes and runs the query. If an

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

@@ -742,7 +742,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                         | (_, Err(ErrorHandled::Reported(_))) => Ok(EvaluatedToErr),
                         (Err(ErrorHandled::Linted), _) | (_, Err(ErrorHandled::Linted)) => {
                             span_bug!(
-                                obligation.cause.span(self.tcx()),
+                                obligation.cause.span(),
                                 "ConstEquate: const_eval_resolve returned an unexpected error"
                             )
                         }

compiler/rustc_typeck/src/astconv/mod.rs

@@ -1958,11 +1958,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         );
                     }
 
-                    if adt_def.did().is_local() {
-                        err.span_label(
-                            tcx.def_span(adt_def.did()),
-                            format!("variant `{assoc_ident}` not found for this enum"),
-                        );
+                    if let Some(sp) = tcx.hir().span_if_local(adt_def.did()) {
+                        err.span_label(sp, format!("variant `{}` not found here", assoc_ident));
                     }
 
                     err.emit()

compiler/rustc_typeck/src/check/_match.rs

@@ -1,6 +1,6 @@
 use crate::check::coercion::{AsCoercionSite, CoerceMany};
 use crate::check::{Diverges, Expectation, FnCtxt, Needs};
-use rustc_errors::{Applicability, Diagnostic, MultiSpan};
+use rustc_errors::{Applicability, MultiSpan};
 use rustc_hir::{self as hir, ExprKind};
 use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::traits::Obligation;
@@ -127,7 +127,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 &cause,
                 Some(&arm.body),
                 arm_ty,
-                Some(&mut |err: &mut Diagnostic| {
+                Some(&mut |err| {
                     let Some(ret) = self.ret_type_span else {
                         return;
                     };

compiler/rustc_typeck/src/check/check.rs

@@ -375,8 +375,9 @@ fn check_alloc_error_fn(
     }
 }
 
-fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId, span: Span) {
+fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     let def = tcx.adt_def(def_id);
+    let span = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
     check_representable(tcx, span, def_id);
 
@@ -388,8 +389,9 @@ fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId, span: Span) {
     check_packed(tcx, span, def);
 }
 
-fn check_union(tcx: TyCtxt<'_>, def_id: LocalDefId, span: Span) {
+fn check_union(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     let def = tcx.adt_def(def_id);
+    let span = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
     check_representable(tcx, span, def_id);
     check_transparent(tcx, span, def);
@@ -471,13 +473,14 @@ fn check_union_fields(tcx: TyCtxt<'_>, span: Span, item_def_id: LocalDefId) -> b
 }
 
 /// Check that a `static` is inhabited.
-fn check_static_inhabited<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId, span: Span) {
+fn check_static_inhabited<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) {
     // Make sure statics are inhabited.
     // Other parts of the compiler assume that there are no uninhabited places. In principle it
     // would be enough to check this for `extern` statics, as statics with an initializer will
     // have UB during initialization if they are uninhabited, but there also seems to be no good
     // reason to allow any statics to be uninhabited.
     let ty = tcx.type_of(def_id);
+    let span = tcx.def_span(def_id);
     let layout = match tcx.layout_of(ParamEnv::reveal_all().and(ty)) {
         Ok(l) => l,
         // Foreign statics that overflow their allowed size should emit an error
@@ -524,9 +527,9 @@ pub(super) fn check_opaque<'tcx>(
     tcx: TyCtxt<'tcx>,
     def_id: LocalDefId,
     substs: SubstsRef<'tcx>,
-    span: Span,
     origin: &hir::OpaqueTyOrigin,
 ) {
+    let span = tcx.def_span(def_id);
     check_opaque_for_inheriting_lifetimes(tcx, def_id, span);
     if tcx.type_of(def_id).references_error() {
         return;
@@ -785,8 +788,8 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
     match tcx.def_kind(id.def_id) {
         DefKind::Static(..) => {
             tcx.ensure().typeck(id.def_id);
-            maybe_check_static_with_link_section(tcx, id.def_id, tcx.def_span(id.def_id));
-            check_static_inhabited(tcx, id.def_id, tcx.def_span(id.def_id));
+            maybe_check_static_with_link_section(tcx, id.def_id);
+            check_static_inhabited(tcx, id.def_id);
         }
         DefKind::Const => {
             tcx.ensure().typeck(id.def_id);
@@ -796,7 +799,7 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
             let hir::ItemKind::Enum(ref enum_definition, _) = item.kind else {
                 return;
             };
-            check_enum(tcx, item.span, &enum_definition.variants, item.def_id);
+            check_enum(tcx, &enum_definition.variants, item.def_id);
         }
         DefKind::Fn => {} // entirely within check_item_body
         DefKind::Impl => {
@@ -847,10 +850,10 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
             }
         }
         DefKind::Struct => {
-            check_struct(tcx, id.def_id, tcx.def_span(id.def_id));
+            check_struct(tcx, id.def_id);
         }
         DefKind::Union => {
-            check_union(tcx, id.def_id, tcx.def_span(id.def_id));
+            check_union(tcx, id.def_id);
         }
         DefKind::OpaqueTy => {
             let item = tcx.hir().item(id);
@@ -863,7 +866,7 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
             // See https://github.com/rust-lang/rust/issues/75100
             if !tcx.sess.opts.actually_rustdoc {
                 let substs = InternalSubsts::identity_for_item(tcx, item.def_id.to_def_id());
-                check_opaque(tcx, item.def_id, substs, item.span, &origin);
+                check_opaque(tcx, item.def_id, substs, &origin);
             }
         }
         DefKind::TyAlias => {
@@ -927,7 +930,7 @@ fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
                             require_c_abi_if_c_variadic(tcx, fn_decl, abi, item.span);
                         }
                         hir::ForeignItemKind::Static(..) => {
-                            check_static_inhabited(tcx, def_id, item.span);
+                            check_static_inhabited(tcx, def_id);
                         }
                         _ => {}
                     }
@@ -1328,7 +1331,6 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: ty::AdtD
     if !adt.repr().transparent() {
         return;
     }
-    let sp = tcx.sess.source_map().guess_head_span(sp);
 
     if adt.is_union() && !tcx.features().transparent_unions {
         feature_err(
@@ -1442,13 +1444,9 @@ pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: ty::AdtD
 }
 
 #[allow(trivial_numeric_casts)]
-fn check_enum<'tcx>(
-    tcx: TyCtxt<'tcx>,
-    sp: Span,
-    vs: &'tcx [hir::Variant<'tcx>],
-    def_id: LocalDefId,
-) {
+fn check_enum<'tcx>(tcx: TyCtxt<'tcx>, vs: &'tcx [hir::Variant<'tcx>], def_id: LocalDefId) {
     let def = tcx.adt_def(def_id);
+    let sp = tcx.def_span(def_id);
     def.destructor(tcx); // force the destructor to be evaluated
 
     if vs.is_empty() {