--- /dev/null
+impl<'tcx> TypeErrCtxt<'_, 'tcx> {
+ fn note_error_origin(
+ &self,
+ err: &mut Diagnostic,
+ cause: &ObligationCause<'tcx>,
+ exp_found: Option<ty::error::ExpectedFound<Ty<'tcx>>>,
+ terr: TypeError<'tcx>,
+ ) {
+ match *cause.code() {
+ ObligationCauseCode::Pattern { origin_expr: true, span: Some(span), root_ty } => {
+ let ty = self.resolve_vars_if_possible(root_ty);
+ if !matches!(ty.kind(), ty::Infer(ty::InferTy::TyVar(_) | ty::InferTy::FreshTy(_)))
+ {
+ // don't show type `_`
+ if span.desugaring_kind() == Some(DesugaringKind::ForLoop)
+ && let ty::Adt(def, substs) = ty.kind()
+ && Some(def.did()) == self.tcx.get_diagnostic_item(sym::Option)
+ {
+ err.span_label(span, format!("this is an iterator with items of type `{}`", substs.type_at(0)));
+ } else {
+ err.span_label(span, format!("this expression has type `{}`", ty));
+ }
+ }
+ if let Some(ty::error::ExpectedFound { found, .. }) = exp_found
+ && ty.is_box() && ty.boxed_ty() == found
+ && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span)
+ {
+ err.span_suggestion(
+ span,
+ "consider dereferencing the boxed value",
+ format!("*{}", snippet),
+ Applicability::MachineApplicable,
+ );
+ }
+ }
+ ObligationCauseCode::Pattern { origin_expr: false, span: Some(span), .. } => {
+ err.span_label(span, "expected due to this");
+ }
+ ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
+ arm_block_id,
+ arm_span,
+ arm_ty,
+ prior_arm_block_id,
+ prior_arm_span,
+ prior_arm_ty,
+ source,
+ ref prior_arms,
+ scrut_hir_id,
+ opt_suggest_box_span,
+ scrut_span,
+ ..
+ }) => match source {
+ hir::MatchSource::TryDesugar => {
+ if let Some(ty::error::ExpectedFound { expected, .. }) = exp_found {
+ let scrut_expr = self.tcx.hir().expect_expr(scrut_hir_id);
+ let scrut_ty = if let hir::ExprKind::Call(_, args) = &scrut_expr.kind {
+ let arg_expr = args.first().expect("try desugaring call w/out arg");
+ self.typeck_results.as_ref().and_then(|typeck_results| {
+ typeck_results.expr_ty_opt(arg_expr)
+ })
+ } else {
+ bug!("try desugaring w/out call expr as scrutinee");
+ };
+
+ match scrut_ty {
+ Some(ty) if expected == ty => {
+ let source_map = self.tcx.sess.source_map();
+ err.span_suggestion(
+ source_map.end_point(cause.span),
+ "try removing this `?`",
+ "",
+ Applicability::MachineApplicable,
+ );
+ }
+ _ => {}
+ }
+ }
+ }
+ _ => {
+ // `prior_arm_ty` can be `!`, `expected` will have better info when present.
+ let t = self.resolve_vars_if_possible(match exp_found {
+ Some(ty::error::ExpectedFound { expected, .. }) => expected,
+ _ => prior_arm_ty,
+ });
+ let source_map = self.tcx.sess.source_map();
+ let mut any_multiline_arm = source_map.is_multiline(arm_span);
+ if prior_arms.len() <= 4 {
+ for sp in prior_arms {
+ any_multiline_arm |= source_map.is_multiline(*sp);
+ err.span_label(*sp, format!("this is found to be of type `{}`", t));
+ }
+ } else if let Some(sp) = prior_arms.last() {
+ any_multiline_arm |= source_map.is_multiline(*sp);
+ err.span_label(
+ *sp,
+ format!("this and all prior arms are found to be of type `{}`", t),
+ );
+ }
+ let outer_error_span = if any_multiline_arm {
+ // Cover just `match` and the scrutinee expression, not
+ // the entire match body, to reduce diagram noise.
+ cause.span.shrink_to_lo().to(scrut_span)
+ } else {
+ cause.span
+ };
+ let msg = "`match` arms have incompatible types";
+ err.span_label(outer_error_span, msg);
+ self.suggest_remove_semi_or_return_binding(
+ err,
+ prior_arm_block_id,
+ prior_arm_ty,
+ prior_arm_span,
+ arm_block_id,
+ arm_ty,
+ arm_span,
+ );
+ if let Some(ret_sp) = opt_suggest_box_span {
+ // Get return type span and point to it.
+ self.suggest_boxing_for_return_impl_trait(
+ err,
+ ret_sp,
+ prior_arms.iter().chain(std::iter::once(&arm_span)).map(|s| *s),
+ );
+ }
+ }
+ },
+ ObligationCauseCode::IfExpression(box IfExpressionCause {
+ then_id,
+ else_id,
+ then_ty,
+ else_ty,
+ outer_span,
+ opt_suggest_box_span,
+ }) => {
+ let then_span = self.find_block_span_from_hir_id(then_id);
+ let else_span = self.find_block_span_from_hir_id(else_id);
+ err.span_label(then_span, "expected because of this");
+ if let Some(sp) = outer_span {
+ err.span_label(sp, "`if` and `else` have incompatible types");
+ }
+ self.suggest_remove_semi_or_return_binding(
+ err,
+ Some(then_id),
+ then_ty,
+ then_span,
+ Some(else_id),
+ else_ty,
+ else_span,
+ );
+ if let Some(ret_sp) = opt_suggest_box_span {
+ self.suggest_boxing_for_return_impl_trait(
+ err,
+ ret_sp,
+ [then_span, else_span].into_iter(),
+ );
+ }
+ }
+ ObligationCauseCode::LetElse => {
+ err.help("try adding a diverging expression, such as `return` or `panic!(..)`");
+ err.help("...or use `match` instead of `let...else`");
+ }
+ _ => {
+ if let ObligationCauseCode::BindingObligation(_, span)
+ | ObligationCauseCode::ExprBindingObligation(_, span, ..)
+ = cause.code().peel_derives()
+ && let TypeError::RegionsPlaceholderMismatch = terr
+ {
+ err.span_note( * span,
+ "the lifetime requirement is introduced here");
+ }
+ }
+ }
+ }
+}
+
+impl<'tcx> InferCtxt<'tcx> {
+ /// Given a [`hir::Block`], get the span of its last expression or
+ /// statement, peeling off any inner blocks.
+ pub fn find_block_span(&self, block: &'tcx hir::Block<'tcx>) -> Span {
+ let block = block.innermost_block();
+ if let Some(expr) = &block.expr {
+ expr.span
+ } else if let Some(stmt) = block.stmts.last() {
+ // possibly incorrect trailing `;` in the else arm
+ stmt.span
+ } else {
+ // empty block; point at its entirety
+ block.span
+ }
+ }
+
+ /// Given a [`hir::HirId`] for a block, get the span of its last expression
+ /// or statement, peeling off any inner blocks.
+ pub fn find_block_span_from_hir_id(&self, hir_id: hir::HirId) -> Span {
+ match self.tcx.hir().get(hir_id) {
+ hir::Node::Block(blk) => self.find_block_span(blk),
+ // The parser was in a weird state if either of these happen, but
+ // it's better not to panic.
+ hir::Node::Expr(e) => e.span,
+ _ => rustc_span::DUMMY_SP,
+ }
+ }
+}
projects / rustc.git / blobdiff