diff options
7 files changed, 218 insertions, 0 deletions
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs index 87ff39a8294..042894beec2 100644 --- a/compiler/rustc_hir/src/hir.rs +++ b/compiler/rustc_hir/src/hir.rs @@ -1038,6 +1038,7 @@ pub struct Block<'hir> { pub hir_id: HirId, /// Distinguishes between `unsafe { ... }` and `{ ... }`. pub rules: BlockCheckMode, + /// The span includes the curly braces `{` and `}` around the block. pub span: Span, /// If true, then there may exist `break 'a` values that aim to /// break out of this block early. diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index c7da85bd1cc..087f7fbea00 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -4587,6 +4587,47 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { _ => "/* value */".to_string(), }) } + + fn suggest_add_result_as_return_type( + &self, + obligation: &PredicateObligation<'tcx>, + err: &mut Diag<'_>, + trait_ref: ty::PolyTraitRef<'tcx>, + ) { + if ObligationCauseCode::QuestionMark != *obligation.cause.code().peel_derives() { + return; + } + + let node = self.tcx.hir_node_by_def_id(obligation.cause.body_id); + if let hir::Node::Item(item) = node + && let hir::ItemKind::Fn(sig, _, body_id) = item.kind + && let hir::FnRetTy::DefaultReturn(ret_span) = sig.decl.output + && self.tcx.is_diagnostic_item(sym::FromResidual, trait_ref.def_id()) + && let ty::Tuple(l) = trait_ref.skip_binder().args.type_at(0).kind() + && l.len() == 0 + && let ty::Adt(def, _) = trait_ref.skip_binder().args.type_at(1).kind() + && self.tcx.is_diagnostic_item(sym::Result, def.did()) + { + let body = self.tcx.hir().body(body_id); + let mut sugg_spans = + vec![(ret_span, " -> Result<(), Box<dyn std::error::Error>>".to_string())]; + + if let hir::ExprKind::Block(b, _) = body.value.kind + && b.expr.is_none() + { + sugg_spans.push(( + // The span will point to the closing curly brace `}` of the block. + b.span.shrink_to_hi().with_lo(b.span.hi() - BytePos(1)), + "\n Ok(())\n}".to_string(), + )); + } + err.multipart_suggestion_verbose( + format!("consider adding return type"), + sugg_spans, + Applicability::MaybeIncorrect, + ); + } + } } /// Add a hint to add a missing borrow or remove an unnecessary one. 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 aeb7f587a26..6b6438a7887 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 @@ -611,6 +611,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> { &mut err, trait_predicate, ); + self.suggest_add_result_as_return_type(&obligation, + &mut err, + trait_ref); + if self.suggest_add_reference_to_arg( &obligation, &mut err, diff --git a/tests/ui/return/return-from-residual-sugg-issue-125997.fixed b/tests/ui/return/return-from-residual-sugg-issue-125997.fixed new file mode 100644 index 00000000000..b2eca69aeb9 --- /dev/null +++ b/tests/ui/return/return-from-residual-sugg-issue-125997.fixed @@ -0,0 +1,42 @@ +//@ run-rustfix + +#![allow(unused_imports)] +#![allow(dead_code)] + +use std::fs::File; +use std::io::prelude::*; + +fn test1() -> Result<(), Box<dyn std::error::Error>> { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + + Ok(()) +} + +fn test2() -> Result<(), Box<dyn std::error::Error>> { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + println!(); + + Ok(()) +} + +macro_rules! mac { + () => { + fn test3() -> Result<(), Box<dyn std::error::Error>> { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + println!(); + + Ok(()) +} + }; +} + +fn main() -> Result<(), Box<dyn std::error::Error>> { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + mac!(); + + Ok(()) +} diff --git a/tests/ui/return/return-from-residual-sugg-issue-125997.rs b/tests/ui/return/return-from-residual-sugg-issue-125997.rs new file mode 100644 index 00000000000..dd8550a388b --- /dev/null +++ b/tests/ui/return/return-from-residual-sugg-issue-125997.rs @@ -0,0 +1,34 @@ +//@ run-rustfix + +#![allow(unused_imports)] +#![allow(dead_code)] + +use std::fs::File; +use std::io::prelude::*; + +fn test1() { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function +} + +fn test2() { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + println!(); +} + +macro_rules! mac { + () => { + fn test3() { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + println!(); + } + }; +} + +fn main() { + let mut _file = File::create("foo.txt")?; + //~^ ERROR the `?` operator can only be used in a function + mac!(); +} diff --git a/tests/ui/return/return-from-residual-sugg-issue-125997.stderr b/tests/ui/return/return-from-residual-sugg-issue-125997.stderr new file mode 100644 index 00000000000..ef938f0213d --- /dev/null +++ b/tests/ui/return/return-from-residual-sugg-issue-125997.stderr @@ -0,0 +1,86 @@ +error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) + --> $DIR/return-from-residual-sugg-issue-125997.rs:10:44 + | +LL | fn test1() { + | ---------- this function should return `Result` or `Option` to accept `?` +LL | let mut _file = File::create("foo.txt")?; + | ^ cannot use the `?` operator in a function that returns `()` + | + = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()` +help: consider adding return type + | +LL ~ fn test1() -> Result<(), Box<dyn std::error::Error>> { +LL | let mut _file = File::create("foo.txt")?; +LL | +LL + +LL + Ok(()) +LL + } + | + +error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) + --> $DIR/return-from-residual-sugg-issue-125997.rs:15:44 + | +LL | fn test2() { + | ---------- this function should return `Result` or `Option` to accept `?` +LL | let mut _file = File::create("foo.txt")?; + | ^ cannot use the `?` operator in a function that returns `()` + | + = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()` +help: consider adding return type + | +LL ~ fn test2() -> Result<(), Box<dyn std::error::Error>> { +LL | let mut _file = File::create("foo.txt")?; +LL | +LL | println!(); +LL + +LL + Ok(()) +LL + } + | + +error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) + --> $DIR/return-from-residual-sugg-issue-125997.rs:31:44 + | +LL | fn main() { + | --------- this function should return `Result` or `Option` to accept `?` +LL | let mut _file = File::create("foo.txt")?; + | ^ cannot use the `?` operator in a function that returns `()` + | + = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()` +help: consider adding return type + | +LL ~ fn main() -> Result<(), Box<dyn std::error::Error>> { +LL | let mut _file = File::create("foo.txt")?; +LL | +LL | mac!(); +LL + +LL + Ok(()) +LL + } + | + +error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `FromResidual`) + --> $DIR/return-from-residual-sugg-issue-125997.rs:23:52 + | +LL | fn test3() { + | ---------- this function should return `Result` or `Option` to accept `?` +LL | let mut _file = File::create("foo.txt")?; + | ^ cannot use the `?` operator in a function that returns `()` +... +LL | mac!(); + | ------ in this macro invocation + | + = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()` + = note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info) +help: consider adding return type + | +LL ~ fn test3() -> Result<(), Box<dyn std::error::Error>> { +LL | let mut _file = File::create("foo.txt")?; +LL | +LL | println!(); +LL ~ +LL + Ok(()) +LL + } + | + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0277`. diff --git a/tests/ui/try-trait/try-operator-on-main.stderr b/tests/ui/try-trait/try-operator-on-main.stderr index 7cd38e0cf95..ba6eacde68f 100644 --- a/tests/ui/try-trait/try-operator-on-main.stderr +++ b/tests/ui/try-trait/try-operator-on-main.stderr @@ -8,6 +8,16 @@ LL | std::fs::File::open("foo")?; | ^ cannot use the `?` operator in a function that returns `()` | = help: the trait `FromResidual<Result<Infallible, std::io::Error>>` is not implemented for `()` +help: consider adding return type + | +LL ~ fn main() -> Result<(), Box<dyn std::error::Error>> { +LL | // error for a `Try` type on a non-`Try` fn + ... +LL | try_trait_generic::<()>(); +LL + +LL + Ok(()) +LL + } + | error[E0277]: the `?` operator can only be applied to values that implement `Try` --> $DIR/try-operator-on-main.rs:10:5 |