diff options
| -rw-r--r-- | compiler/rustc_span/src/symbol.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs | 235 | ||||
| -rw-r--r-- | tests/ui/traits/question-mark-result-err-mismatch.rs | 59 | ||||
| -rw-r--r-- | tests/ui/traits/question-mark-result-err-mismatch.stderr | 62 | ||||
| -rw-r--r-- | tests/ui/try-block/try-block-bad-type.stderr | 4 | ||||
| -rw-r--r-- | tests/ui/try-trait/bad-interconversion.stderr | 4 | ||||
| -rw-r--r-- | tests/ui/try-trait/issue-32709.stderr | 4 |
7 files changed, 364 insertions, 6 deletions
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs index d7e822382ef..07fe3a23147 100644 --- a/compiler/rustc_span/src/symbol.rs +++ b/compiler/rustc_span/src/symbol.rs @@ -973,6 +973,7 @@ symbols! { managed_boxes, manually_drop, map, + map_err, marker, marker_trait_attr, masked, @@ -1137,6 +1138,7 @@ symbols! { offset, offset_of, offset_of_enum, + ok_or_else, omit_gdb_pretty_printer_section, on, on_unimplemented, diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs index 85774013062..090706070eb 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs @@ -3,6 +3,7 @@ use super::suggestions::{get_explanation_based_on_obligation, TypeErrCtxtExt as use crate::errors::{ClosureFnMutLabel, ClosureFnOnceLabel, ClosureKindMismatch}; use crate::infer::error_reporting::{TyCategory, TypeAnnotationNeeded as ErrorCode}; use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use crate::infer::InferCtxtExt as _; use crate::infer::{self, InferCtxt}; use crate::traits::error_reporting::infer_ctxt_ext::InferCtxtExt; use crate::traits::error_reporting::{ambiguity, ambiguity::Ambiguity::*}; @@ -40,7 +41,7 @@ use rustc_session::config::{DumpSolverProofTree, TraitSolver}; use rustc_session::Limit; use rustc_span::def_id::LOCAL_CRATE; use rustc_span::symbol::sym; -use rustc_span::{ExpnKind, Span, DUMMY_SP}; +use rustc_span::{BytePos, ExpnKind, Span, Symbol, DUMMY_SP}; use std::borrow::Cow; use std::fmt; use std::iter; @@ -106,6 +107,13 @@ pub trait TypeErrCtxtExt<'tcx> { fn fn_arg_obligation(&self, obligation: &PredicateObligation<'tcx>) -> bool; + fn try_conversion_context( + &self, + obligation: &PredicateObligation<'tcx>, + trait_ref: ty::TraitRef<'tcx>, + err: &mut Diagnostic, + ) -> bool; + fn report_const_param_not_wf( &self, ty: Ty<'tcx>, @@ -509,6 +517,11 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { let mut err = struct_span_err!(self.tcx.sess, span, E0277, "{}", err_msg); + let mut suggested = false; + if is_try_conversion { + suggested = self.try_conversion_context(&obligation, trait_ref.skip_binder(), &mut err); + } + if is_try_conversion && let Some(ret_span) = self.return_type_span(&obligation) { err.span_label( ret_span, @@ -609,8 +622,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { self.suggest_floating_point_literal(&obligation, &mut err, &trait_ref); self.suggest_dereferencing_index(&obligation, &mut err, trait_predicate); - let mut suggested = - self.suggest_dereferences(&obligation, &mut err, trait_predicate); + suggested |= self.suggest_dereferences(&obligation, &mut err, trait_predicate); suggested |= self.suggest_fn_call(&obligation, &mut err, trait_predicate); let impl_candidates = self.find_similar_impl_candidates(trait_predicate); suggested = if let &[cand] = &impl_candidates[..] { @@ -982,6 +994,223 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> { false } + /// When the `E` of the resulting `Result<T, E>` in an expression `foo().bar().baz()?`, + /// identify thoe method chain sub-expressions that could or could not have been annotated + /// with `?`. + fn try_conversion_context( + &self, + obligation: &PredicateObligation<'tcx>, + trait_ref: ty::TraitRef<'tcx>, + err: &mut Diagnostic, + ) -> bool { + let span = obligation.cause.span; + struct V<'v> { + search_span: Span, + found: Option<&'v hir::Expr<'v>>, + } + impl<'v> Visitor<'v> for V<'v> { + fn visit_expr(&mut self, ex: &'v hir::Expr<'v>) { + if let hir::ExprKind::Match(expr, _arms, hir::MatchSource::TryDesugar(_)) = ex.kind + { + if ex.span.with_lo(ex.span.hi() - BytePos(1)).source_equal(self.search_span) { + if let hir::ExprKind::Call(_, [expr, ..]) = expr.kind { + self.found = Some(expr); + return; + } + } + } + hir::intravisit::walk_expr(self, ex); + } + } + let hir_id = self.tcx.local_def_id_to_hir_id(obligation.cause.body_id); + let body_id = match self.tcx.hir().find(hir_id) { + Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. })) => { + body_id + } + _ => return false, + }; + let mut v = V { search_span: span, found: None }; + v.visit_body(self.tcx.hir().body(*body_id)); + let Some(expr) = v.found else { + return false; + }; + let Some(typeck) = &self.typeck_results else { + return false; + }; + let Some((ObligationCauseCode::QuestionMark, Some(y))) = obligation.cause.code().parent() + else { + return false; + }; + if !self.tcx.is_diagnostic_item(sym::FromResidual, y.def_id()) { + return false; + } + let self_ty = trait_ref.self_ty(); + let found_ty = trait_ref.args.get(1).and_then(|a| a.as_type()); + + let mut prev_ty = self.resolve_vars_if_possible( + typeck.expr_ty_adjusted_opt(expr).unwrap_or(Ty::new_misc_error(self.tcx)), + ); + + // We always look at the `E` type, because that's the only one affected by `?`. If the + // incorrect `Result<T, E>` is because of the `T`, we'll get an E0308 on the whole + // expression, after the `?` has "unwrapped" the `T`. + let get_e_type = |prev_ty: Ty<'tcx>| -> Option<Ty<'tcx>> { + let ty::Adt(def, args) = prev_ty.kind() else { + return None; + }; + let Some(arg) = args.get(1) else { + return None; + }; + if !self.tcx.is_diagnostic_item(sym::Result, def.did()) { + return None; + } + Some(arg.as_type()?) + }; + + let mut suggested = false; + let mut chain = vec![]; + + // The following logic is simlar to `point_at_chain`, but that's focused on associated types + let mut expr = expr; + while let hir::ExprKind::MethodCall(path_segment, rcvr_expr, args, span) = expr.kind { + // Point at every method call in the chain with the `Result` type. + // let foo = bar.iter().map(mapper)?; + // ------ ----------- + expr = rcvr_expr; + chain.push((span, prev_ty)); + + let next_ty = self.resolve_vars_if_possible( + typeck.expr_ty_adjusted_opt(expr).unwrap_or(Ty::new_misc_error(self.tcx)), + ); + + let is_diagnostic_item = |symbol: Symbol, ty: Ty<'tcx>| { + let ty::Adt(def, _) = ty.kind() else { + return false; + }; + self.tcx.is_diagnostic_item(symbol, def.did()) + }; + // For each method in the chain, see if this is `Result::map_err` or + // `Option::ok_or_else` and if it is, see if the closure passed to it has an incorrect + // trailing `;`. + if let Some(ty) = get_e_type(prev_ty) + && let Some(found_ty) = found_ty + // Ideally we would instead use `FnCtxt::lookup_method_for_diagnostic` for 100% + // accurate check, but we are in the wrong stage to do that and looking for + // `Result::map_err` by checking the Self type and the path segment is enough. + // sym::ok_or_else + && ( + ( // Result::map_err + path_segment.ident.name == sym::map_err + && is_diagnostic_item(sym::Result, next_ty) + ) || ( // Option::ok_or_else + path_segment.ident.name == sym::ok_or_else + && is_diagnostic_item(sym::Option, next_ty) + ) + ) + // Found `Result<_, ()>?` + && let ty::Tuple(tys) = found_ty.kind() + && tys.is_empty() + // The current method call returns `Result<_, ()>` + && self.can_eq(obligation.param_env, ty, found_ty) + // There's a single argument in the method call and it is a closure + && args.len() == 1 + && let Some(arg) = args.get(0) + && let hir::ExprKind::Closure(closure) = arg.kind + // The closure has a block for its body with no tail expression + && let body = self.tcx.hir().body(closure.body) + && let hir::ExprKind::Block(block, _) = body.value.kind + && let None = block.expr + // The last statement is of a type that can be converted to the return error type + && let [.., stmt] = block.stmts + && let hir::StmtKind::Semi(expr) = stmt.kind + && let expr_ty = self.resolve_vars_if_possible( + typeck.expr_ty_adjusted_opt(expr) + .unwrap_or(Ty::new_misc_error(self.tcx)), + ) + && self + .infcx + .type_implements_trait( + self.tcx.get_diagnostic_item(sym::From).unwrap(), + [self_ty, expr_ty], + obligation.param_env, + ) + .must_apply_modulo_regions() + { + suggested = true; + err.span_suggestion_short( + stmt.span.with_lo(expr.span.hi()), + "remove this semicolon", + String::new(), + Applicability::MachineApplicable, + ); + } + + prev_ty = next_ty; + + if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind + && let hir::Path { res: hir::def::Res::Local(hir_id), .. } = path + && let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(*hir_id) + && let Some(parent) = self.tcx.hir().find_parent(binding.hir_id) + { + // We've reached the root of the method call chain... + if let hir::Node::Local(local) = parent + && let Some(binding_expr) = local.init + { + // ...and it is a binding. Get the binding creation and continue the chain. + expr = binding_expr; + } + if let hir::Node::Param(_param) = parent { + // ...and it is a an fn argument. + break; + } + } + } + // `expr` is now the "root" expression of the method call chain, which can be any + // expression kind, like a method call or a path. If this expression is `Result<T, E>` as + // well, then we also point at it. + prev_ty = self.resolve_vars_if_possible( + typeck.expr_ty_adjusted_opt(expr).unwrap_or(Ty::new_misc_error(self.tcx)), + ); + chain.push((expr.span, prev_ty)); + + let mut prev = None; + for (span, err_ty) in chain.into_iter().rev() { + let err_ty = get_e_type(err_ty); + let err_ty = match (err_ty, prev) { + (Some(err_ty), Some(prev)) if !self.can_eq(obligation.param_env, err_ty, prev) => { + err_ty + } + (Some(err_ty), None) => err_ty, + _ => { + prev = err_ty; + continue; + } + }; + if self + .infcx + .type_implements_trait( + self.tcx.get_diagnostic_item(sym::From).unwrap(), + [self_ty, err_ty], + obligation.param_env, + ) + .must_apply_modulo_regions() + { + if !suggested { + err.span_label(span, format!("this has type `Result<_, {err_ty}>`")); + } + } else { + err.span_label( + span, + format!( + "this can't be annotated with `?` because it has type `Result<_, {err_ty}>`", + ), + ); + } + prev = Some(err_ty); + } + suggested + } + fn report_const_param_not_wf( &self, ty: Ty<'tcx>, diff --git a/tests/ui/traits/question-mark-result-err-mismatch.rs b/tests/ui/traits/question-mark-result-err-mismatch.rs new file mode 100644 index 00000000000..0ca18b5b0dd --- /dev/null +++ b/tests/ui/traits/question-mark-result-err-mismatch.rs @@ -0,0 +1,59 @@ +fn foo() -> Result<String, String> { //~ NOTE expected `String` because of this + let test = String::from("one,two"); + let x = test + .split_whitespace() + .next() + .ok_or_else(|| { + "Couldn't split the test string" + }); + let one = x + .map(|s| ()) + .map_err(|e| { //~ NOTE this can't be annotated with `?` because it has type `Result<_, ()>` + e; //~ HELP remove this semicolon + }) + .map(|()| "")?; //~ ERROR `?` couldn't convert the error to `String` + //~^ NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE the trait `From<()>` is not implemented for `String` + //~| NOTE the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait + //~| NOTE required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>` + Ok(one.to_string()) +} + +fn bar() -> Result<(), String> { //~ NOTE expected `String` because of this + let x = foo(); //~ NOTE this has type `Result<_, String>` + let one = x + .map(|s| ()) + .map_err(|_| ())?; //~ ERROR `?` couldn't convert the error to `String` + //~^ NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE this can't be annotated with `?` because it has type `Result<_, ()>` + //~| NOTE the trait `From<()>` is not implemented for `String` + //~| NOTE the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait + //~| NOTE required for `Result<(), String>` to implement `FromResidual<Result<Infallible, ()>>` + //~| HELP the following other types implement trait `From<T>`: + Ok(one) +} + +fn baz() -> Result<String, String> { //~ NOTE expected `String` because of this + let test = String::from("one,two"); + let one = test + .split_whitespace() + .next() + .ok_or_else(|| { //~ NOTE this can't be annotated with `?` because it has type `Result<_, ()>` + "Couldn't split the test string"; //~ HELP remove this semicolon + })?; + //~^ ERROR `?` couldn't convert the error to `String` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE in this expansion of desugaring of operator `?` + //~| NOTE the trait `From<()>` is not implemented for `String` + //~| NOTE the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait + //~| NOTE required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>` + Ok(one.to_string()) +} + +fn main() {} diff --git a/tests/ui/traits/question-mark-result-err-mismatch.stderr b/tests/ui/traits/question-mark-result-err-mismatch.stderr new file mode 100644 index 00000000000..3059e0beca3 --- /dev/null +++ b/tests/ui/traits/question-mark-result-err-mismatch.stderr @@ -0,0 +1,62 @@ +error[E0277]: `?` couldn't convert the error to `String` + --> $DIR/question-mark-result-err-mismatch.rs:14:22 + | +LL | fn foo() -> Result<String, String> { + | ---------------------- expected `String` because of this +... +LL | .map_err(|e| { + | __________- +LL | | e; + | | - help: remove this semicolon +LL | | }) + | |__________- this can't be annotated with `?` because it has type `Result<_, ()>` +LL | .map(|()| "")?; + | ^ the trait `From<()>` is not implemented for `String` + | + = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait + = note: required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>` + +error[E0277]: `?` couldn't convert the error to `String` + --> $DIR/question-mark-result-err-mismatch.rs:28:25 + | +LL | fn bar() -> Result<(), String> { + | ------------------ expected `String` because of this +LL | let x = foo(); + | ----- this has type `Result<_, String>` +... +LL | .map_err(|_| ())?; + | ---------------^ the trait `From<()>` is not implemented for `String` + | | + | this can't be annotated with `?` because it has type `Result<_, ()>` + | + = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait + = help: the following other types implement trait `From<T>`: + <String as From<char>> + <String as From<Box<str>>> + <String as From<Cow<'a, str>>> + <String as From<&str>> + <String as From<&mut str>> + <String as From<&String>> + = note: required for `Result<(), String>` to implement `FromResidual<Result<Infallible, ()>>` + +error[E0277]: `?` couldn't convert the error to `String` + --> $DIR/question-mark-result-err-mismatch.rs:48:11 + | +LL | fn baz() -> Result<String, String> { + | ---------------------- expected `String` because of this +... +LL | .ok_or_else(|| { + | __________- +LL | | "Couldn't split the test string"; + | | - help: remove this semicolon +LL | | })?; + | | -^ the trait `From<()>` is not implemented for `String` + | |__________| + | this can't be annotated with `?` because it has type `Result<_, ()>` + | + = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait + = note: required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>` + +error: aborting due to 3 previous errors + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/try-block/try-block-bad-type.stderr b/tests/ui/try-block/try-block-bad-type.stderr index b41bf86d3d9..d58a011ff55 100644 --- a/tests/ui/try-block/try-block-bad-type.stderr +++ b/tests/ui/try-block/try-block-bad-type.stderr @@ -2,7 +2,9 @@ error[E0277]: `?` couldn't convert the error to `TryFromSliceError` --> $DIR/try-block-bad-type.rs:7:16 | LL | Err("")?; - | ^ the trait `From<&str>` is not implemented for `TryFromSliceError` + | -------^ the trait `From<&str>` is not implemented for `TryFromSliceError` + | | + | this can't be annotated with `?` because it has type `Result<_, &str>` | = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait = help: the trait `From<Infallible>` is implemented for `TryFromSliceError` diff --git a/tests/ui/try-trait/bad-interconversion.stderr b/tests/ui/try-trait/bad-interconversion.stderr index d8b9431becc..97fbbdbf8f8 100644 --- a/tests/ui/try-trait/bad-interconversion.stderr +++ b/tests/ui/try-trait/bad-interconversion.stderr @@ -4,7 +4,9 @@ error[E0277]: `?` couldn't convert the error to `u8` LL | fn result_to_result() -> Result<u64, u8> { | --------------- expected `u8` because of this LL | Ok(Err(123_i32)?) - | ^ the trait `From<i32>` is not implemented for `u8` + | ------------^ the trait `From<i32>` is not implemented for `u8` + | | + | this can't be annotated with `?` because it has type `Result<_, i32>` | = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait = help: the following other types implement trait `From<T>`: diff --git a/tests/ui/try-trait/issue-32709.stderr b/tests/ui/try-trait/issue-32709.stderr index 46798f5dcfd..b155b3ff663 100644 --- a/tests/ui/try-trait/issue-32709.stderr +++ b/tests/ui/try-trait/issue-32709.stderr @@ -4,7 +4,9 @@ error[E0277]: `?` couldn't convert the error to `()` LL | fn a() -> Result<i32, ()> { | --------------- expected `()` because of this LL | Err(5)?; - | ^ the trait `From<{integer}>` is not implemented for `()` + | ------^ the trait `From<{integer}>` is not implemented for `()` + | | + | this can't be annotated with `?` because it has type `Result<_, {integer}>` | = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait = help: the following other types implement trait `From<T>`: |