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mikhail-m1mikhail-m1
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add hint to fix error for immutable ref in arg
1 parent 0b399e5 commit 67a24c2

15 files changed

+342
-46
lines changed

‎src/librustc_borrowck/borrowck/mod.rs

+83-46
Original file line numberDiff line numberDiff line change
@@ -24,7 +24,7 @@ use self::InteriorKind::*;
2424

2525
use rustc::dep_graph::DepNode;
2626
use rustc::hir::map as hir_map;
27-
use rustc::hir::map::blocks::FnParts;
27+
use rustc::hir::map::blocks::{FnParts, FnLikeNode};
2828
use rustc::cfg;
2929
use rustc::middle::dataflow::DataFlowContext;
3030
use rustc::middle::dataflow::BitwiseOperator;
@@ -970,51 +970,8 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
970970

971971
pub fn note_and_explain_bckerr(&self, db: &mut DiagnosticBuilder, err: BckError<'tcx>,
972972
error_span: Span) {
973-
let code = err.code;
974-
match code {
975-
err_mutbl => {
976-
match err.cmt.note {
977-
mc::NoteClosureEnv(upvar_id) | mc::NoteUpvarRef(upvar_id) => {
978-
// If this is an `Fn` closure, it simply can't mutate upvars.
979-
// If it's an `FnMut` closure, the original variable was declared immutable.
980-
// We need to determine which is the case here.
981-
let kind = match err.cmt.upvar().unwrap().cat {
982-
Categorization::Upvar(mc::Upvar { kind, .. }) => kind,
983-
_ => bug!()
984-
};
985-
if kind == ty::ClosureKind::Fn {
986-
db.span_help(
987-
self.tcx.map.span(upvar_id.closure_expr_id),
988-
"consider changing this closure to take \
989-
self by mutable reference");
990-
}
991-
}
992-
_ => {
993-
if let Categorization::Local(local_id) = err.cmt.cat {
994-
let span = self.tcx.map.span(local_id);
995-
if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
996-
if snippet.starts_with("ref mut ") || snippet.starts_with("&mut ") {
997-
db.span_label(error_span, &format!("cannot reborrow mutably"));
998-
db.span_label(error_span, &format!("try removing `&mut` here"));
999-
} else {
1000-
if snippet.starts_with("ref ") {
1001-
db.span_label(span,
1002-
&format!("use `{}` here to make mutable",
1003-
snippet.replace("ref ", "ref mut ")));
1004-
} else if snippet != "self" {
1005-
db.span_label(span,
1006-
&format!("use `mut {}` here to make mutable", snippet));
1007-
}
1008-
db.span_label(error_span, &format!("cannot borrow mutably"));
1009-
}
1010-
} else {
1011-
db.span_label(error_span, &format!("cannot borrow mutably"));
1012-
}
1013-
}
1014-
}
1015-
}
1016-
}
1017-
973+
match err.code {
974+
err_mutbl => self.note_and_explain_mutbl_error(db, &err, &error_span),
1018975
err_out_of_scope(super_scope, sub_scope, cause) => {
1019976
let (value_kind, value_msg) = match err.cmt.cat {
1020977
mc::Categorization::Rvalue(_) =>
@@ -1135,6 +1092,86 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
11351092
}
11361093
}
11371094

1095+
fn note_and_explain_mutbl_error(&self, db: &mut DiagnosticBuilder, err: &BckError<'tcx>,
1096+
error_span: &Span) {
1097+
match err.cmt.note {
1098+
mc::NoteClosureEnv(upvar_id) | mc::NoteUpvarRef(upvar_id) => {
1099+
// If this is an `Fn` closure, it simply can't mutate upvars.
1100+
// If it's an `FnMut` closure, the original variable was declared immutable.
1101+
// We need to determine which is the case here.
1102+
let kind = match err.cmt.upvar().unwrap().cat {
1103+
Categorization::Upvar(mc::Upvar { kind, .. }) => kind,
1104+
_ => bug!()
1105+
};
1106+
if kind == ty::ClosureKind::Fn {
1107+
db.span_help(self.tcx.map.span(upvar_id.closure_expr_id),
1108+
"consider changing this closure to take \
1109+
self by mutable reference");
1110+
}
1111+
}
1112+
_ => {
1113+
if let Categorization::Deref(ref inner_cmt, ..) = err.cmt.cat {
1114+
if let Categorization::Local(local_id) = inner_cmt.cat {
1115+
let parent = self.tcx.map.get_parent_node(local_id);
1116+
let opt_fn_decl = FnLikeNode::from_node(self.tcx.map.get(parent))
1117+
.map(|fn_like| fn_like.decl());
1118+
1119+
if let Some(fn_decl) = opt_fn_decl {
1120+
if let Some(ref arg) = fn_decl.inputs.iter()
1121+
.find(|ref arg| arg.pat.id == local_id) {
1122+
if let hir::TyRptr(
1123+
opt_lifetime,
1124+
hir::MutTy{mutbl: hir::Mutability::MutImmutable, ref ty}) =
1125+
arg.ty.node {
1126+
if let Some(lifetime) = opt_lifetime {
1127+
if let Ok(snippet) = self.tcx.sess.codemap()
1128+
.span_to_snippet(ty.span) {
1129+
if let Ok(lifetime_snippet) = self.tcx.sess.codemap()
1130+
.span_to_snippet(lifetime.span) {
1131+
db.span_label(arg.ty.span,
1132+
&format!("use `&{} mut {}` \
1133+
here to make mutable",
1134+
lifetime_snippet,
1135+
snippet));
1136+
}
1137+
}
1138+
}
1139+
else if let Ok(snippet) = self.tcx.sess.codemap()
1140+
.span_to_snippet(arg.ty.span) {
1141+
if snippet.starts_with("&") {
1142+
db.span_label(arg.ty.span,
1143+
&format!("use `{}` here to make mutable",
1144+
snippet.replace("&", "&mut ")));
1145+
}
1146+
}
1147+
}
1148+
}
1149+
}
1150+
}
1151+
} else if let Categorization::Local(local_id) = err.cmt.cat {
1152+
let span = self.tcx.map.span(local_id);
1153+
if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
1154+
if snippet.starts_with("ref mut ") || snippet.starts_with("&mut ") {
1155+
db.span_label(*error_span, &format!("cannot reborrow mutably"));
1156+
db.span_label(*error_span, &format!("try removing `&mut` here"));
1157+
} else {
1158+
if snippet.starts_with("ref ") {
1159+
db.span_label(span, &format!("use `{}` here to make mutable",
1160+
snippet.replace("ref ", "ref mut ")));
1161+
} else if snippet != "self" {
1162+
db.span_label(span,
1163+
&format!("use `mut {}` here to make mutable",
1164+
snippet));
1165+
}
1166+
db.span_label(*error_span, &format!("cannot borrow mutably"));
1167+
}
1168+
} else {
1169+
db.span_label(*error_span, &format!("cannot borrow mutably"));
1170+
}
1171+
}
1172+
}
1173+
}
1174+
}
11381175
pub fn append_loan_path_to_string(&self,
11391176
loan_path: &LoanPath<'tcx>,
11401177
out: &mut String) {

‎src/test/compile-fail/borrowck/borrowck-borrow-overloaded-auto-deref-mut.rs renamed to ‎src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.rs

File renamed without changes.

‎src/test/ui/span/borrowck-borrow-overloaded-auto-deref-mut.stderr

+86
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,86 @@
1+
error: cannot borrow immutable argument `x` as mutable
2+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:63:24
3+
|
4+
62 | fn deref_mut_field1(x: Own<Point>) {
5+
| - use `mut x` here to make mutable
6+
63 | let __isize = &mut x.y; //~ ERROR cannot borrow
7+
| ^ cannot borrow mutably
8+
9+
error: cannot borrow immutable borrowed content `*x` as mutable
10+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:75:10
11+
|
12+
74 | fn deref_extend_mut_field1(x: &Own<Point>) -> &mut isize {
13+
| ----------- use `&mut Own<Point>` here to make mutable
14+
75 | &mut x.y //~ ERROR cannot borrow
15+
| ^
16+
17+
error[E0499]: cannot borrow `*x` as mutable more than once at a time
18+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:88:19
19+
|
20+
87 | let _x = &mut x.x;
21+
| - first mutable borrow occurs here
22+
88 | let _y = &mut x.y; //~ ERROR cannot borrow
23+
| ^ second mutable borrow occurs here
24+
89 | }
25+
| - first borrow ends here
26+
27+
error: cannot borrow immutable argument `x` as mutable
28+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:98:5
29+
|
30+
97 | fn assign_field1<'a>(x: Own<Point>) {
31+
| - use `mut x` here to make mutable
32+
98 | x.y = 3; //~ ERROR cannot borrow
33+
| ^ cannot borrow mutably
34+
35+
error: cannot borrow immutable borrowed content `*x` as mutable
36+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:102:5
37+
|
38+
101 | fn assign_field2<'a>(x: &'a Own<Point>) {
39+
| -------------- use `&'a mut Own<Point>` here to make mutable
40+
102 | x.y = 3; //~ ERROR cannot borrow
41+
| ^
42+
43+
error[E0499]: cannot borrow `*x` as mutable more than once at a time
44+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:111:5
45+
|
46+
110 | let _p: &mut Point = &mut **x;
47+
| -- first mutable borrow occurs here
48+
111 | x.y = 3; //~ ERROR cannot borrow
49+
| ^ second mutable borrow occurs here
50+
112 | }
51+
| - first borrow ends here
52+
53+
error: cannot borrow immutable argument `x` as mutable
54+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:119:5
55+
|
56+
118 | fn deref_mut_method1(x: Own<Point>) {
57+
| - use `mut x` here to make mutable
58+
119 | x.set(0, 0); //~ ERROR cannot borrow
59+
| ^ cannot borrow mutably
60+
61+
error: cannot borrow immutable borrowed content `*x` as mutable
62+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:131:5
63+
|
64+
130 | fn deref_extend_mut_method1(x: &Own<Point>) -> &mut isize {
65+
| ----------- use `&mut Own<Point>` here to make mutable
66+
131 | x.y_mut() //~ ERROR cannot borrow
67+
| ^
68+
69+
error: cannot borrow immutable argument `x` as mutable
70+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:139:6
71+
|
72+
138 | fn assign_method1<'a>(x: Own<Point>) {
73+
| - use `mut x` here to make mutable
74+
139 | *x.y_mut() = 3; //~ ERROR cannot borrow
75+
| ^ cannot borrow mutably
76+
77+
error: cannot borrow immutable borrowed content `*x` as mutable
78+
--> $DIR/borrowck-borrow-overloaded-auto-deref-mut.rs:143:6
79+
|
80+
142 | fn assign_method2<'a>(x: &'a Own<Point>) {
81+
| -------------- use `&'a mut Own<Point>` here to make mutable
82+
143 | *x.y_mut() = 3; //~ ERROR cannot borrow
83+
| ^
84+
85+
error: aborting due to 10 previous errors
86+

‎src/test/compile-fail/borrowck/borrowck-borrow-overloaded-deref-mut.rs renamed to ‎src/test/ui/span/borrowck-borrow-overloaded-deref-mut.rs

File renamed without changes.

‎src/test/ui/span/borrowck-borrow-overloaded-deref-mut.stderr

+34
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
error: cannot borrow immutable argument `x` as mutable
2+
--> $DIR/borrowck-borrow-overloaded-deref-mut.rs:39:25
3+
|
4+
38 | fn deref_mut1(x: Own<isize>) {
5+
| - use `mut x` here to make mutable
6+
39 | let __isize = &mut *x; //~ ERROR cannot borrow
7+
| ^ cannot borrow mutably
8+
9+
error: cannot borrow immutable borrowed content `*x` as mutable
10+
--> $DIR/borrowck-borrow-overloaded-deref-mut.rs:51:11
11+
|
12+
50 | fn deref_extend_mut1<'a>(x: &'a Own<isize>) -> &'a mut isize {
13+
| -------------- use `&'a mut Own<isize>` here to make mutable
14+
51 | &mut **x //~ ERROR cannot borrow
15+
| ^^
16+
17+
error: cannot borrow immutable argument `x` as mutable
18+
--> $DIR/borrowck-borrow-overloaded-deref-mut.rs:59:6
19+
|
20+
58 | fn assign1<'a>(x: Own<isize>) {
21+
| - use `mut x` here to make mutable
22+
59 | *x = 3; //~ ERROR cannot borrow
23+
| ^ cannot borrow mutably
24+
25+
error: cannot borrow immutable borrowed content `*x` as mutable
26+
--> $DIR/borrowck-borrow-overloaded-deref-mut.rs:63:6
27+
|
28+
62 | fn assign2<'a>(x: &'a Own<isize>) {
29+
| -------------- use `&'a mut Own<isize>` here to make mutable
30+
63 | **x = 3; //~ ERROR cannot borrow
31+
| ^^
32+
33+
error: aborting due to 4 previous errors
34+

‎src/test/compile-fail/borrowck/borrowck-call-is-borrow-issue-12224.rs renamed to ‎src/test/ui/span/borrowck-call-is-borrow-issue-12224.rs

File renamed without changes.

‎src/test/ui/span/borrowck-call-is-borrow-issue-12224.stderr

+43
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,43 @@
1+
error[E0499]: cannot borrow `f` as mutable more than once at a time
2+
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:23:16
3+
|
4+
23 | f(Box::new(|| {
5+
| - ^^ second mutable borrow occurs here
6+
| |
7+
| first mutable borrow occurs here
8+
24 | //~^ ERROR: cannot borrow `f` as mutable more than once
9+
25 | f((Box::new(|| {})))
10+
| - borrow occurs due to use of `f` in closure
11+
26 | }));
12+
| - first borrow ends here
13+
14+
error: cannot borrow immutable borrowed content `*f` as mutable
15+
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:36:5
16+
|
17+
35 | fn test2<F>(f: &F) where F: FnMut() {
18+
| -- use `&mut F` here to make mutable
19+
36 | (*f)(); //~ ERROR: cannot borrow immutable borrowed content `*f` as mutable
20+
| ^^^^
21+
22+
error: cannot borrow immutable `Box` content `*f.f` as mutable
23+
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:44:5
24+
|
25+
44 | f.f.call_mut(()) //~ ERROR: cannot borrow immutable `Box` content `*f.f` as mutable
26+
| ^^^
27+
28+
error[E0504]: cannot move `f` into closure because it is borrowed
29+
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:63:13
30+
|
31+
62 | f(Box::new(|a| {
32+
| - borrow of `f` occurs here
33+
63 | foo(f);
34+
| ^ move into closure occurs here
35+
36+
error[E0507]: cannot move out of captured outer variable in an `FnMut` closure
37+
--> $DIR/borrowck-call-is-borrow-issue-12224.rs:63:13
38+
|
39+
63 | foo(f);
40+
| ^ cannot move out of captured outer variable in an `FnMut` closure
41+
42+
error: aborting due to 5 previous errors
43+

‎src/test/compile-fail/borrowck/borrowck-call-method-from-mut-aliasable.rs renamed to ‎src/test/ui/span/borrowck-call-method-from-mut-aliasable.rs

File renamed without changes.

‎src/test/ui/span/borrowck-call-method-from-mut-aliasable.stderr

+11
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
error: cannot borrow immutable borrowed content `*x` as mutable
2+
--> $DIR/borrowck-call-method-from-mut-aliasable.rs:27:5
3+
|
4+
25 | fn b(x: &Foo) {
5+
| ---- use `&mut Foo` here to make mutable
6+
26 | x.f();
7+
27 | x.h(); //~ ERROR cannot borrow
8+
| ^
9+
10+
error: aborting due to previous error
11+

‎src/test/compile-fail/borrowck/borrowck-fn-in-const-b.rs renamed to ‎src/test/ui/span/borrowck-fn-in-const-b.rs

File renamed without changes.

‎src/test/ui/span/borrowck-fn-in-const-b.stderr

+10
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
1+
error: cannot borrow immutable borrowed content `*x` as mutable
2+
--> $DIR/borrowck-fn-in-const-b.rs:17:9
3+
|
4+
16 | fn broken(x: &Vec<String>) {
5+
| ------------ use `&mut Vec<String>` here to make mutable
6+
17 | x.push(format!("this is broken"));
7+
| ^
8+
9+
error: aborting due to previous error
10+

‎src/test/compile-fail/borrowck/borrowck-object-mutability.rs renamed to ‎src/test/ui/span/borrowck-object-mutability.rs

File renamed without changes.

‎src/test/ui/span/borrowck-object-mutability.stderr

+17
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,17 @@
1+
error: cannot borrow immutable borrowed content `*x` as mutable
2+
--> $DIR/borrowck-object-mutability.rs:19:5
3+
|
4+
17 | fn borrowed_receiver(x: &Foo) {
5+
| ---- use `&mut Foo` here to make mutable
6+
18 | x.borrowed();
7+
19 | x.borrowed_mut(); //~ ERROR cannot borrow
8+
| ^
9+
10+
error: cannot borrow immutable `Box` content `*x` as mutable
11+
--> $DIR/borrowck-object-mutability.rs:29:5
12+
|
13+
29 | x.borrowed_mut(); //~ ERROR cannot borrow
14+
| ^
15+
16+
error: aborting due to 2 previous errors
17+

‎src/test/ui/span/mut-arg-hint.rs

+32
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,32 @@
1+
// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
2+
// file at the top-level directory of this distribution and at
3+
// http://rust-lang.org/COPYRIGHT.
4+
//
5+
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6+
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7+
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8+
// option. This file may not be copied, modified, or distributed
9+
// except according to those terms.
10+
11+
trait B {
12+
fn foo(mut a: &String) {
13+
a.push_str("bar");
14+
}
15+
}
16+
17+
pub fn foo<'a>(mut a: &'a String) {
18+
a.push_str("foo");
19+
}
20+
21+
struct A {}
22+
23+
impl A {
24+
pub fn foo(mut a: &String) {
25+
a.push_str("foo");
26+
}
27+
}
28+
29+
fn main() {
30+
foo(&"a".to_string());
31+
A::foo(&"a".to_string());
32+
}

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