diff --git a/src/librustc_borrowck/borrowck/mod.rs b/src/librustc_borrowck/borrowck/mod.rs index 7c2d5ba094ffa..79b4382369217 100644 --- a/src/librustc_borrowck/borrowck/mod.rs +++ b/src/librustc_borrowck/borrowck/mod.rs @@ -39,6 +39,7 @@ use rustc::middle::free_region::RegionRelations; use rustc::ty::{self, Ty, TyCtxt}; use rustc::ty::query::Providers; use rustc_mir::util::borrowck_errors::{BorrowckErrors, Origin}; +use rustc_mir::util::suggest_ref_mut; use rustc::util::nodemap::FxHashSet; use std::cell::RefCell; @@ -1206,15 +1207,15 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> { self.note_immutable_local(db, error_node_id, node_id) } Some(ImmutabilityBlame::LocalDeref(node_id)) => { - let let_span = self.tcx.hir.span(node_id); match self.local_binding_mode(node_id) { ty::BindByReference(..) => { - let snippet = self.tcx.sess.codemap().span_to_snippet(let_span); - if let Ok(snippet) = snippet { - db.span_label( + let let_span = self.tcx.hir.span(node_id); + let suggestion = suggest_ref_mut(self.tcx, let_span); + if let Some((let_span, replace_str)) = suggestion { + db.span_suggestion( let_span, - format!("consider changing this to `{}`", - snippet.replace("ref ", "ref mut ")) + "use a mutable reference instead", + replace_str, ); } } diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs index 1a66a2d2cb902..7078d77f3fb2b 100644 --- a/src/librustc_mir/borrow_check/mod.rs +++ b/src/librustc_mir/borrow_check/mod.rs @@ -44,6 +44,7 @@ use dataflow::{EverInitializedPlaces, MovingOutStatements}; use dataflow::{MaybeInitializedPlaces, MaybeUninitializedPlaces}; use util::borrowck_errors::{BorrowckErrors, Origin}; use util::collect_writes::FindAssignments; +use util::suggest_ref_mut; use self::borrow_set::{BorrowData, BorrowSet}; use self::flows::Flows; @@ -1837,17 +1838,41 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> { Place::Projection(box Projection { base: Place::Local(local), elem: ProjectionElem::Deref, - }) if self.mir.local_decls[*local].is_nonref_binding() => - { - let (err_help_span, suggested_code) = - find_place_to_suggest_ampmut(self.tcx, self.mir, *local); - err.span_suggestion( - err_help_span, - "consider changing this to be a mutable reference", - suggested_code, - ); - + }) if self.mir.local_decls[*local].is_user_variable.is_some() => { let local_decl = &self.mir.local_decls[*local]; + let suggestion = match local_decl.is_user_variable.as_ref().unwrap() { + ClearCrossCrate::Set(mir::BindingForm::ImplicitSelf) => { + Some(suggest_ampmut_self(local_decl)) + }, + + ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm { + binding_mode: ty::BindingMode::BindByValue(_), + opt_ty_info, + .. + })) => Some(suggest_ampmut( + self.tcx, + self.mir, + *local, + local_decl, + *opt_ty_info, + )), + + ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm { + binding_mode: ty::BindingMode::BindByReference(_), + .. + })) => suggest_ref_mut(self.tcx, local_decl.source_info.span), + + ClearCrossCrate::Clear => bug!("saw cleared local state"), + }; + + if let Some((err_help_span, suggested_code)) = suggestion { + err.span_suggestion( + err_help_span, + "consider changing this to be a mutable reference", + suggested_code, + ); + } + if let Some(name) = local_decl.name { err.span_label( span, @@ -1874,13 +1899,16 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> { err.emit(); return true; - // Returns the span to highlight and the associated text to - // present when suggesting that the user use an `&mut`. - // + fn suggest_ampmut_self<'cx, 'gcx, 'tcx>( + local_decl: &mir::LocalDecl<'tcx>, + ) -> (Span, String) { + (local_decl.source_info.span, "&mut self".to_string()) + } + // When we want to suggest a user change a local variable to be a `&mut`, there // are three potential "obvious" things to highlight: // - // let ident [: Type] [= RightHandSideExresssion]; + // let ident [: Type] [= RightHandSideExpression]; // ^^^^^ ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^ // (1.) (2.) (3.) // @@ -1889,48 +1917,44 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> { // for example, if the RHS is present and the Type is not, then the type is going to // be inferred *from* the RHS, which means we should highlight that (and suggest // that they borrow the RHS mutably). - fn find_place_to_suggest_ampmut<'cx, 'gcx, 'tcx>( + // + // This implementation attempts to emulate AST-borrowck prioritization + // by trying (3.), then (2.) and finally falling back on (1.). + fn suggest_ampmut<'cx, 'gcx, 'tcx>( tcx: TyCtxt<'cx, 'gcx, 'tcx>, mir: &Mir<'tcx>, local: Local, + local_decl: &mir::LocalDecl<'tcx>, + opt_ty_info: Option, ) -> (Span, String) { - // This implementation attempts to emulate AST-borrowck prioritization - // by trying (3.), then (2.) and finally falling back on (1.). let locations = mir.find_assignments(local); if locations.len() > 0 { let assignment_rhs_span = mir.source_info(locations[0]).span; let snippet = tcx.sess.codemap().span_to_snippet(assignment_rhs_span); if let Ok(src) = snippet { - // pnkfelix inherited code; believes intention is - // highlighted text will always be `&` and - // thus can transform to `&mut` by slicing off - // first ASCII character and prepending "&mut ". if src.starts_with('&') { let borrowed_expr = src[1..].to_string(); - return (assignment_rhs_span, format!("&mut {}", borrowed_expr)); + return ( + assignment_rhs_span, + format!("&mut {}", borrowed_expr), + ); } } } - let local_decl = &mir.local_decls[local]; - let highlight_span = match local_decl.is_user_variable { + let highlight_span = match opt_ty_info { // if this is a variable binding with an explicit type, // try to highlight that for the suggestion. - Some(ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm { - opt_ty_info: Some(ty_span), - .. - }))) => ty_span, - - Some(ClearCrossCrate::Clear) => bug!("saw cleared local state"), + Some(ty_span) => ty_span, // otherwise, just highlight the span associated with // the (MIR) LocalDecl. - _ => local_decl.source_info.span, + None => local_decl.source_info.span, }; let ty_mut = local_decl.ty.builtin_deref(true).unwrap(); assert_eq!(ty_mut.mutbl, hir::MutImmutable); - return (highlight_span, format!("&mut {}", ty_mut.ty)); + (highlight_span, format!("&mut {}", ty_mut.ty)) } } diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs index dc0d0b244633f..92c0a2b475c20 100644 --- a/src/librustc_mir/lib.rs +++ b/src/librustc_mir/lib.rs @@ -33,6 +33,7 @@ Rust MIR: a lowered representation of Rust. Also: an experiment! #![feature(never_type)] #![feature(specialization)] #![feature(try_trait)] +#![feature(unicode_internals)] #![recursion_limit="256"] @@ -56,6 +57,7 @@ extern crate rustc_target; extern crate log_settings; extern crate rustc_apfloat; extern crate byteorder; +extern crate core; mod diagnostics; diff --git a/src/librustc_mir/util/mod.rs b/src/librustc_mir/util/mod.rs index 19cd376688627..78e9dd23e83ae 100644 --- a/src/librustc_mir/util/mod.rs +++ b/src/librustc_mir/util/mod.rs @@ -8,6 +8,10 @@ // option. This file may not be copied, modified, or distributed // except according to those terms. +use core::unicode::property::Pattern_White_Space; +use rustc::ty; +use syntax_pos::Span; + pub mod borrowck_errors; pub mod elaborate_drops; pub mod def_use; @@ -23,3 +27,19 @@ pub use self::alignment::is_disaligned; pub use self::pretty::{dump_enabled, dump_mir, write_mir_pretty, PassWhere}; pub use self::graphviz::{write_mir_graphviz}; pub use self::graphviz::write_node_label as write_graphviz_node_label; + +/// If possible, suggest replacing `ref` with `ref mut`. +pub fn suggest_ref_mut<'cx, 'gcx, 'tcx>( + tcx: ty::TyCtxt<'cx, 'gcx, 'tcx>, + pattern_span: Span, +) -> Option<(Span, String)> { + let hi_src = tcx.sess.codemap().span_to_snippet(pattern_span).unwrap(); + if hi_src.starts_with("ref") + && hi_src["ref".len()..].starts_with(Pattern_White_Space) + { + let replacement = format!("ref mut{}", &hi_src["ref".len()..]); + Some((pattern_span, replacement)) + } else { + None + } +} diff --git a/src/test/ui/did_you_mean/issue-38147-1.nll.stderr b/src/test/ui/did_you_mean/issue-38147-1.nll.stderr index 76b8c8ebf6029..d156d64b9d693 100644 --- a/src/test/ui/did_you_mean/issue-38147-1.nll.stderr +++ b/src/test/ui/did_you_mean/issue-38147-1.nll.stderr @@ -2,7 +2,7 @@ error[E0596]: cannot borrow immutable item `*self.s` as mutable --> $DIR/issue-38147-1.rs:27:9 | LL | fn f(&self) { - | ----- help: consider changing this to be a mutable reference: `&mut Foo<'_>` + | ----- help: consider changing this to be a mutable reference: `&mut self` LL | self.s.push('x'); //~ ERROR cannot borrow data mutably | ^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable diff --git a/src/test/ui/did_you_mean/issue-39544.nll.stderr b/src/test/ui/did_you_mean/issue-39544.nll.stderr index 02c1debca69b2..e2d2fcd63db12 100644 --- a/src/test/ui/did_you_mean/issue-39544.nll.stderr +++ b/src/test/ui/did_you_mean/issue-39544.nll.stderr @@ -10,7 +10,7 @@ error[E0596]: cannot borrow immutable item `self.x` as mutable --> $DIR/issue-39544.rs:26:17 | LL | fn foo<'z>(&'z self) { - | -------- help: consider changing this to be a mutable reference: `&mut Z` + | -------- help: consider changing this to be a mutable reference: `&mut self` LL | let _ = &mut self.x; //~ ERROR cannot borrow | ^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable @@ -18,7 +18,7 @@ error[E0596]: cannot borrow immutable item `self.x` as mutable --> $DIR/issue-39544.rs:30:17 | LL | fn foo1(&self, other: &Z) { - | ----- help: consider changing this to be a mutable reference: `&mut Z` + | ----- help: consider changing this to be a mutable reference: `&mut self` LL | let _ = &mut self.x; //~ ERROR cannot borrow | ^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable @@ -35,7 +35,7 @@ error[E0596]: cannot borrow immutable item `self.x` as mutable --> $DIR/issue-39544.rs:35:17 | LL | fn foo2<'a>(&'a self, other: &Z) { - | -------- help: consider changing this to be a mutable reference: `&mut Z` + | -------- help: consider changing this to be a mutable reference: `&mut self` LL | let _ = &mut self.x; //~ ERROR cannot borrow | ^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be borrowed as mutable diff --git a/src/test/ui/nll/issue-51244.rs b/src/test/ui/nll/issue-51244.rs new file mode 100644 index 0000000000000..f00ad3d6505be --- /dev/null +++ b/src/test/ui/nll/issue-51244.rs @@ -0,0 +1,17 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(nll)] + +fn main() { + let ref my_ref @ _ = 0; + *my_ref = 0; + //~^ ERROR cannot assign to `*my_ref` which is behind a `&` reference [E0594] +} diff --git a/src/test/ui/nll/issue-51244.stderr b/src/test/ui/nll/issue-51244.stderr new file mode 100644 index 0000000000000..4e04aec8fe1af --- /dev/null +++ b/src/test/ui/nll/issue-51244.stderr @@ -0,0 +1,11 @@ +error[E0594]: cannot assign to `*my_ref` which is behind a `&` reference + --> $DIR/issue-51244.rs:15:5 + | +LL | let ref my_ref @ _ = 0; + | -------------- help: consider changing this to be a mutable reference: `ref mut my_ref @ _` +LL | *my_ref = 0; + | ^^^^^^^^^^^ `my_ref` is a `&` reference, so the data it refers to cannot be written + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0594`. diff --git a/src/test/ui/rfc-2005-default-binding-mode/enum.nll.stderr b/src/test/ui/rfc-2005-default-binding-mode/enum.nll.stderr index 8aa7e8a417c2b..a9b2bca434cba 100644 --- a/src/test/ui/rfc-2005-default-binding-mode/enum.nll.stderr +++ b/src/test/ui/rfc-2005-default-binding-mode/enum.nll.stderr @@ -2,19 +2,19 @@ error[E0594]: cannot assign to `*x` which is behind a `&` reference --> $DIR/enum.rs:19:5 | LL | *x += 1; //~ ERROR cannot assign to immutable - | ^^^^^^^ cannot assign + | ^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be written error[E0594]: cannot assign to `*x` which is behind a `&` reference --> $DIR/enum.rs:23:9 | LL | *x += 1; //~ ERROR cannot assign to immutable - | ^^^^^^^ cannot assign + | ^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be written error[E0594]: cannot assign to `*x` which is behind a `&` reference --> $DIR/enum.rs:29:9 | LL | *x += 1; //~ ERROR cannot assign to immutable - | ^^^^^^^ cannot assign + | ^^^^^^^ `x` is a `&` reference, so the data it refers to cannot be written error: aborting due to 3 previous errors diff --git a/src/test/ui/rfc-2005-default-binding-mode/enum.stderr b/src/test/ui/rfc-2005-default-binding-mode/enum.stderr index a7f3b507508e8..ad05de9f3575f 100644 --- a/src/test/ui/rfc-2005-default-binding-mode/enum.stderr +++ b/src/test/ui/rfc-2005-default-binding-mode/enum.stderr @@ -1,24 +1,18 @@ error[E0594]: cannot assign to immutable borrowed content `*x` --> $DIR/enum.rs:19:5 | -LL | let Wrap(x) = &Wrap(3); - | - consider changing this to `x` LL | *x += 1; //~ ERROR cannot assign to immutable | ^^^^^^^ cannot borrow as mutable error[E0594]: cannot assign to immutable borrowed content `*x` --> $DIR/enum.rs:23:9 | -LL | if let Some(x) = &Some(3) { - | - consider changing this to `x` LL | *x += 1; //~ ERROR cannot assign to immutable | ^^^^^^^ cannot borrow as mutable error[E0594]: cannot assign to immutable borrowed content `*x` --> $DIR/enum.rs:29:9 | -LL | while let Some(x) = &Some(3) { - | - consider changing this to `x` LL | *x += 1; //~ ERROR cannot assign to immutable | ^^^^^^^ cannot borrow as mutable diff --git a/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.nll.stderr b/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.nll.stderr index 4e00dec761621..4c6149a8b7b30 100644 --- a/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.nll.stderr +++ b/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.nll.stderr @@ -2,19 +2,19 @@ error[E0594]: cannot assign to `*n` which is behind a `&` reference --> $DIR/explicit-mut.rs:17:13 | LL | *n += 1; //~ ERROR cannot assign to immutable - | ^^^^^^^ cannot assign + | ^^^^^^^ `n` is a `&` reference, so the data it refers to cannot be written error[E0594]: cannot assign to `*n` which is behind a `&` reference --> $DIR/explicit-mut.rs:25:13 | LL | *n += 1; //~ ERROR cannot assign to immutable - | ^^^^^^^ cannot assign + | ^^^^^^^ `n` is a `&` reference, so the data it refers to cannot be written error[E0594]: cannot assign to `*n` which is behind a `&` reference --> $DIR/explicit-mut.rs:33:13 | LL | *n += 1; //~ ERROR cannot assign to immutable - | ^^^^^^^ cannot assign + | ^^^^^^^ `n` is a `&` reference, so the data it refers to cannot be written error: aborting due to 3 previous errors diff --git a/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr b/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr index f2b9bde41ab33..8da67a6b5ee65 100644 --- a/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr +++ b/src/test/ui/rfc-2005-default-binding-mode/explicit-mut.stderr @@ -1,24 +1,18 @@ error[E0594]: cannot assign to immutable borrowed content `*n` --> $DIR/explicit-mut.rs:17:13 | -LL | Some(n) => { - | - consider changing this to `n` LL | *n += 1; //~ ERROR cannot assign to immutable | ^^^^^^^ cannot borrow as mutable error[E0594]: cannot assign to immutable borrowed content `*n` --> $DIR/explicit-mut.rs:25:13 | -LL | Some(n) => { - | - consider changing this to `n` LL | *n += 1; //~ ERROR cannot assign to immutable | ^^^^^^^ cannot borrow as mutable error[E0594]: cannot assign to immutable borrowed content `*n` --> $DIR/explicit-mut.rs:33:13 | -LL | Some(n) => { - | - consider changing this to `n` LL | *n += 1; //~ ERROR cannot assign to immutable | ^^^^^^^ cannot borrow as mutable diff --git a/src/test/ui/suggestions/issue-51244.nll.stderr b/src/test/ui/suggestions/issue-51244.nll.stderr new file mode 100644 index 0000000000000..ce02ae2aec23f --- /dev/null +++ b/src/test/ui/suggestions/issue-51244.nll.stderr @@ -0,0 +1,11 @@ +error[E0594]: cannot assign to `*my_ref` which is behind a `&` reference + --> $DIR/issue-51244.rs:13:5 + | +LL | let ref my_ref @ _ = 0; + | -------------- help: consider changing this to be a mutable reference: `ref mut my_ref @ _` +LL | *my_ref = 0; //~ ERROR cannot assign to immutable borrowed content `*my_ref` [E0594] + | ^^^^^^^^^^^ `my_ref` is a `&` reference, so the data it refers to cannot be written + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0594`. diff --git a/src/test/ui/suggestions/issue-51244.rs b/src/test/ui/suggestions/issue-51244.rs new file mode 100644 index 0000000000000..50a21184a98b9 --- /dev/null +++ b/src/test/ui/suggestions/issue-51244.rs @@ -0,0 +1,14 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +fn main() { + let ref my_ref @ _ = 0; + *my_ref = 0; //~ ERROR cannot assign to immutable borrowed content `*my_ref` [E0594] +} diff --git a/src/test/ui/suggestions/issue-51244.stderr b/src/test/ui/suggestions/issue-51244.stderr new file mode 100644 index 0000000000000..997a74295e565 --- /dev/null +++ b/src/test/ui/suggestions/issue-51244.stderr @@ -0,0 +1,11 @@ +error[E0594]: cannot assign to immutable borrowed content `*my_ref` + --> $DIR/issue-51244.rs:13:5 + | +LL | let ref my_ref @ _ = 0; + | -------------- help: use a mutable reference instead: `ref mut my_ref @ _` +LL | *my_ref = 0; //~ ERROR cannot assign to immutable borrowed content `*my_ref` [E0594] + | ^^^^^^^^^^^ cannot borrow as mutable + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0594`. diff --git a/src/test/ui/suggestions/suggest-ref-mut.rs b/src/test/ui/suggestions/suggest-ref-mut.rs new file mode 100644 index 0000000000000..30b5371af1ac5 --- /dev/null +++ b/src/test/ui/suggestions/suggest-ref-mut.rs @@ -0,0 +1,42 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(nll)] + +struct X(usize); + +impl X { + fn zap(&self) { + //~^ HELP + //~| SUGGESTION &mut self + self.0 = 32; + //~^ ERROR + } +} + +fn main() { + let ref foo = 16; + //~^ HELP + //~| SUGGESTION ref mut foo + *foo = 32; + //~^ ERROR + if let Some(ref bar) = Some(16) { + //~^ HELP + //~| SUGGESTION ref mut bar + *bar = 32; + //~^ ERROR + } + match 16 { + ref quo => { *quo = 32; }, + //~^ ERROR + //~| HELP + //~| SUGGESTION ref mut quo + } +} diff --git a/src/test/ui/suggestions/suggest-ref-mut.stderr b/src/test/ui/suggestions/suggest-ref-mut.stderr new file mode 100644 index 0000000000000..0b2b240ef53a8 --- /dev/null +++ b/src/test/ui/suggestions/suggest-ref-mut.stderr @@ -0,0 +1,38 @@ +error[E0594]: cannot assign to `self.0` which is behind a `&` reference + --> $DIR/suggest-ref-mut.rs:19:9 + | +LL | fn zap(&self) { + | ----- help: consider changing this to be a mutable reference: `&mut self` +... +LL | self.0 = 32; + | ^^^^^^^^^^^ `self` is a `&` reference, so the data it refers to cannot be written + +error[E0594]: cannot assign to `*foo` which is behind a `&` reference + --> $DIR/suggest-ref-mut.rs:28:5 + | +LL | let ref foo = 16; + | ------- help: consider changing this to be a mutable reference: `ref mut foo` +... +LL | *foo = 32; + | ^^^^^^^^^ `foo` is a `&` reference, so the data it refers to cannot be written + +error[E0594]: cannot assign to `*bar` which is behind a `&` reference + --> $DIR/suggest-ref-mut.rs:33:9 + | +LL | if let Some(ref bar) = Some(16) { + | ------- help: consider changing this to be a mutable reference: `ref mut bar` +... +LL | *bar = 32; + | ^^^^^^^^^ `bar` is a `&` reference, so the data it refers to cannot be written + +error[E0594]: cannot assign to `*quo` which is behind a `&` reference + --> $DIR/suggest-ref-mut.rs:37:22 + | +LL | ref quo => { *quo = 32; }, + | ------- ^^^^^^^^^ `quo` is a `&` reference, so the data it refers to cannot be written + | | + | help: consider changing this to be a mutable reference: `ref mut quo` + +error: aborting due to 4 previous errors + +For more information about this error, try `rustc --explain E0594`.