diff --git a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs index 31e863b8a4ed6..54a557c514547 100644 --- a/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs @@ -1,9 +1,10 @@ +use hir::ExprKind; use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed}; use rustc_hir as hir; use rustc_hir::intravisit::Visitor; use rustc_hir::Node; use rustc_middle::mir::{Mutability, Place, PlaceRef, ProjectionElem}; -use rustc_middle::ty::{self, Ty, TyCtxt}; +use rustc_middle::ty::{self, InstanceDef, Ty, TyCtxt}; use rustc_middle::{ hir::place::PlaceBase, mir::{self, BindingForm, Local, LocalDecl, LocalInfo, LocalKind, Location}, @@ -491,6 +492,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { ), ); + self.suggest_using_iter_mut(&mut err); self.suggest_make_local_mut(&mut err, local, name); } _ => { @@ -953,6 +955,44 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { } } + fn suggest_using_iter_mut(&self, err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>) { + let source = self.body.source; + let hir = self.infcx.tcx.hir(); + if let InstanceDef::Item(def_id) = source.instance + && let Some(Node::Expr(hir::Expr { hir_id, kind, ..})) = hir.get_if_local(def_id) + && let ExprKind::Closure(closure) = kind && closure.movability == None + && let Some(Node::Expr(expr)) = hir.find_parent(*hir_id) { + let mut cur_expr = expr; + while let ExprKind::MethodCall(path_segment, recv, _, _) = cur_expr.kind { + if path_segment.ident.name == sym::iter { + // check `_ty` has `iter_mut` method + let res = self + .infcx + .tcx + .typeck(path_segment.hir_id.owner.def_id) + .type_dependent_def_id(cur_expr.hir_id) + .and_then(|def_id| self.infcx.tcx.impl_of_method(def_id)) + .map(|def_id| self.infcx.tcx.associated_items(def_id)) + .map(|assoc_items| { + assoc_items.filter_by_name_unhygienic(sym::iter_mut).peekable() + }); + + if let Some(mut res) = res && res.peek().is_some() { + err.span_suggestion_verbose( + path_segment.ident.span, + "you may want to use `iter_mut` here", + "iter_mut", + Applicability::MaybeIncorrect, + ); + } + break; + } else { + cur_expr = recv; + } + } + } + } + fn suggest_make_local_mut( &self, err: &mut DiagnosticBuilder<'_, ErrorGuaranteed>, diff --git a/tests/ui/borrowck/issue-115259-suggest-iter-mut.fixed b/tests/ui/borrowck/issue-115259-suggest-iter-mut.fixed new file mode 100644 index 0000000000000..4653fe7375d38 --- /dev/null +++ b/tests/ui/borrowck/issue-115259-suggest-iter-mut.fixed @@ -0,0 +1,20 @@ +// run-rustfix +#![allow(unused_mut)] +#![allow(dead_code)] + +pub trait Layer { + fn process(&mut self) -> u32; +} + +pub struct State { + layers: Vec>, +} + +impl State { + pub fn process(&mut self) -> u32 { + self.layers.iter_mut().fold(0, |result, mut layer| result + layer.process()) + //~^ ERROR cannot borrow `**layer` as mutable, as it is behind a `&` reference + } +} + +fn main() {} diff --git a/tests/ui/borrowck/issue-115259-suggest-iter-mut.rs b/tests/ui/borrowck/issue-115259-suggest-iter-mut.rs new file mode 100644 index 0000000000000..e0f6ab1321f83 --- /dev/null +++ b/tests/ui/borrowck/issue-115259-suggest-iter-mut.rs @@ -0,0 +1,20 @@ +// run-rustfix +#![allow(unused_mut)] +#![allow(dead_code)] + +pub trait Layer { + fn process(&mut self) -> u32; +} + +pub struct State { + layers: Vec>, +} + +impl State { + pub fn process(&mut self) -> u32 { + self.layers.iter().fold(0, |result, mut layer| result + layer.process()) + //~^ ERROR cannot borrow `**layer` as mutable, as it is behind a `&` reference + } +} + +fn main() {} diff --git a/tests/ui/borrowck/issue-115259-suggest-iter-mut.stderr b/tests/ui/borrowck/issue-115259-suggest-iter-mut.stderr new file mode 100644 index 0000000000000..7e0fc2cf298b0 --- /dev/null +++ b/tests/ui/borrowck/issue-115259-suggest-iter-mut.stderr @@ -0,0 +1,16 @@ +error[E0596]: cannot borrow `**layer` as mutable, as it is behind a `&` reference + --> $DIR/issue-115259-suggest-iter-mut.rs:15:65 + | +LL | self.layers.iter().fold(0, |result, mut layer| result + layer.process()) + | --------- ^^^^^ `layer` is a `&` reference, so the data it refers to cannot be borrowed as mutable + | | + | consider changing this binding's type to be: `&mut Box` + | +help: you may want to use `iter_mut` here + | +LL | self.layers.iter_mut().fold(0, |result, mut layer| result + layer.process()) + | ~~~~~~~~ + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0596`. diff --git a/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.fixed b/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.fixed new file mode 100644 index 0000000000000..f02374d8e11de --- /dev/null +++ b/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.fixed @@ -0,0 +1,36 @@ +// run-rustfix +#![allow(unused_mut)] +#![allow(dead_code)] +use std::path::PathBuf; + +#[derive(Clone)] +struct Container { + things: Vec, +} + +impl Container { + fn things(&mut self) -> &[PathBuf] { + &self.things + } +} + +// contains containers +struct ContainerContainer { + contained: Vec, +} + +impl ContainerContainer { + fn contained(&self) -> &[Container] { + &self.contained + } + + fn all_the_things(&mut self) -> &[PathBuf] { + let mut vec = self.contained.clone(); + let _a = + vec.iter_mut().flat_map(|container| container.things()).cloned().collect::>(); + //~^ ERROR cannot borrow `*container` as mutable, as it is behind a `&` reference + unimplemented!(); + } +} + +fn main() {} diff --git a/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.rs b/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.rs new file mode 100644 index 0000000000000..2d0b837a946ca --- /dev/null +++ b/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.rs @@ -0,0 +1,36 @@ +// run-rustfix +#![allow(unused_mut)] +#![allow(dead_code)] +use std::path::PathBuf; + +#[derive(Clone)] +struct Container { + things: Vec, +} + +impl Container { + fn things(&mut self) -> &[PathBuf] { + &self.things + } +} + +// contains containers +struct ContainerContainer { + contained: Vec, +} + +impl ContainerContainer { + fn contained(&self) -> &[Container] { + &self.contained + } + + fn all_the_things(&mut self) -> &[PathBuf] { + let mut vec = self.contained.clone(); + let _a = + vec.iter().flat_map(|container| container.things()).cloned().collect::>(); + //~^ ERROR cannot borrow `*container` as mutable, as it is behind a `&` reference + unimplemented!(); + } +} + +fn main() {} diff --git a/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.stderr b/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.stderr new file mode 100644 index 0000000000000..19f194100a199 --- /dev/null +++ b/tests/ui/borrowck/issue-62387-suggest-iter-mut-2.stderr @@ -0,0 +1,16 @@ +error[E0596]: cannot borrow `*container` as mutable, as it is behind a `&` reference + --> $DIR/issue-62387-suggest-iter-mut-2.rs:30:45 + | +LL | vec.iter().flat_map(|container| container.things()).cloned().collect::>(); + | --------- ^^^^^^^^^ `container` is a `&` reference, so the data it refers to cannot be borrowed as mutable + | | + | consider changing this binding's type to be: `&mut Container` + | +help: you may want to use `iter_mut` here + | +LL | vec.iter_mut().flat_map(|container| container.things()).cloned().collect::>(); + | ~~~~~~~~ + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0596`. diff --git a/tests/ui/borrowck/issue-62387-suggest-iter-mut.fixed b/tests/ui/borrowck/issue-62387-suggest-iter-mut.fixed new file mode 100644 index 0000000000000..8bf2625de6da6 --- /dev/null +++ b/tests/ui/borrowck/issue-62387-suggest-iter-mut.fixed @@ -0,0 +1,30 @@ +// run-rustfix +#![allow(unused_mut)] +#![allow(dead_code)] + +#[derive(Debug)] +struct A { + a: i32, +} + +impl A { + fn double(&mut self) { + self.a += self.a + } +} + +fn baz() { + let mut v = [A { a: 4 }]; + v.iter_mut().for_each(|a| a.double()); + //~^ ERROR cannot borrow `*a` as mutable, as it is behind a `&` reference + println!("{:?}", v); +} + +fn bar() { + let mut v = [A { a: 4 }]; + v.iter_mut().rev().rev().for_each(|a| a.double()); + //~^ ERROR cannot borrow `*a` as mutable, as it is behind a `&` reference + println!("{:?}", v); +} + +fn main() {} diff --git a/tests/ui/borrowck/issue-62387-suggest-iter-mut.rs b/tests/ui/borrowck/issue-62387-suggest-iter-mut.rs new file mode 100644 index 0000000000000..39bc30bf29452 --- /dev/null +++ b/tests/ui/borrowck/issue-62387-suggest-iter-mut.rs @@ -0,0 +1,30 @@ +// run-rustfix +#![allow(unused_mut)] +#![allow(dead_code)] + +#[derive(Debug)] +struct A { + a: i32, +} + +impl A { + fn double(&mut self) { + self.a += self.a + } +} + +fn baz() { + let mut v = [A { a: 4 }]; + v.iter().for_each(|a| a.double()); + //~^ ERROR cannot borrow `*a` as mutable, as it is behind a `&` reference + println!("{:?}", v); +} + +fn bar() { + let mut v = [A { a: 4 }]; + v.iter().rev().rev().for_each(|a| a.double()); + //~^ ERROR cannot borrow `*a` as mutable, as it is behind a `&` reference + println!("{:?}", v); +} + +fn main() {} diff --git a/tests/ui/borrowck/issue-62387-suggest-iter-mut.stderr b/tests/ui/borrowck/issue-62387-suggest-iter-mut.stderr new file mode 100644 index 0000000000000..fd58e43302025 --- /dev/null +++ b/tests/ui/borrowck/issue-62387-suggest-iter-mut.stderr @@ -0,0 +1,29 @@ +error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference + --> $DIR/issue-62387-suggest-iter-mut.rs:18:27 + | +LL | v.iter().for_each(|a| a.double()); + | - ^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable + | | + | consider changing this binding's type to be: `&mut A` + | +help: you may want to use `iter_mut` here + | +LL | v.iter_mut().for_each(|a| a.double()); + | ~~~~~~~~ + +error[E0596]: cannot borrow `*a` as mutable, as it is behind a `&` reference + --> $DIR/issue-62387-suggest-iter-mut.rs:25:39 + | +LL | v.iter().rev().rev().for_each(|a| a.double()); + | - ^ `a` is a `&` reference, so the data it refers to cannot be borrowed as mutable + | | + | consider changing this binding's type to be: `&mut A` + | +help: you may want to use `iter_mut` here + | +LL | v.iter_mut().rev().rev().for_each(|a| a.double()); + | ~~~~~~~~ + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0596`.