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Auto merge of #37863 - mikhail-m1:mut_error, r=nikomatsakis
add hint to fix error for immutable ref in arg fix #36412 part of #35233 r? @jonathandturner
2 parents b30022a + 67a24c2 commit fa0005f

15 files changed

+342
-46
lines changed

‎src/librustc_borrowck/borrowck/mod.rs‎

Lines changed: 83 additions & 46 deletions
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;
@@ -978,51 +978,8 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
978978

979979
pub fn note_and_explain_bckerr(&self, db: &mut DiagnosticBuilder, err: BckError<'tcx>,
980980
error_span: Span) {
981-
let code = err.code;
982-
match code {
983-
err_mutbl => {
984-
match err.cmt.note {
985-
mc::NoteClosureEnv(upvar_id) | mc::NoteUpvarRef(upvar_id) => {
986-
// If this is an `Fn` closure, it simply can't mutate upvars.
987-
// If it's an `FnMut` closure, the original variable was declared immutable.
988-
// We need to determine which is the case here.
989-
let kind = match err.cmt.upvar().unwrap().cat {
990-
Categorization::Upvar(mc::Upvar { kind, .. }) => kind,
991-
_ => bug!()
992-
};
993-
if kind == ty::ClosureKind::Fn {
994-
db.span_help(
995-
self.tcx.map.span(upvar_id.closure_expr_id),
996-
"consider changing this closure to take \
997-
self by mutable reference");
998-
}
999-
}
1000-
_ => {
1001-
if let Categorization::Local(local_id) = err.cmt.cat {
1002-
let span = self.tcx.map.span(local_id);
1003-
if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
1004-
if snippet.starts_with("ref mut ") || snippet.starts_with("&mut ") {
1005-
db.span_label(error_span, &format!("cannot reborrow mutably"));
1006-
db.span_label(error_span, &format!("try removing `&mut` here"));
1007-
} else {
1008-
if snippet.starts_with("ref ") {
1009-
db.span_label(span,
1010-
&format!("use `{}` here to make mutable",
1011-
snippet.replace("ref ", "ref mut ")));
1012-
} else if snippet != "self" {
1013-
db.span_label(span,
1014-
&format!("use `mut {}` here to make mutable", snippet));
1015-
}
1016-
db.span_label(error_span, &format!("cannot borrow mutably"));
1017-
}
1018-
} else {
1019-
db.span_label(error_span, &format!("cannot borrow mutably"));
1020-
}
1021-
}
1022-
}
1023-
}
1024-
}
1025-
981+
match err.code {
982+
err_mutbl => self.note_and_explain_mutbl_error(db, &err, &error_span),
1026983
err_out_of_scope(super_scope, sub_scope, cause) => {
1027984
let (value_kind, value_msg) = match err.cmt.cat {
1028985
mc::Categorization::Rvalue(_) =>
@@ -1143,6 +1100,86 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
11431100
}
11441101
}
11451102

1103+
fn note_and_explain_mutbl_error(&self, db: &mut DiagnosticBuilder, err: &BckError<'tcx>,
1104+
error_span: &Span) {
1105+
match err.cmt.note {
1106+
mc::NoteClosureEnv(upvar_id) | mc::NoteUpvarRef(upvar_id) => {
1107+
// If this is an `Fn` closure, it simply can't mutate upvars.
1108+
// If it's an `FnMut` closure, the original variable was declared immutable.
1109+
// We need to determine which is the case here.
1110+
let kind = match err.cmt.upvar().unwrap().cat {
1111+
Categorization::Upvar(mc::Upvar { kind, .. }) => kind,
1112+
_ => bug!()
1113+
};
1114+
if kind == ty::ClosureKind::Fn {
1115+
db.span_help(self.tcx.map.span(upvar_id.closure_expr_id),
1116+
"consider changing this closure to take \
1117+
self by mutable reference");
1118+
}
1119+
}
1120+
_ => {
1121+
if let Categorization::Deref(ref inner_cmt, ..) = err.cmt.cat {
1122+
if let Categorization::Local(local_id) = inner_cmt.cat {
1123+
let parent = self.tcx.map.get_parent_node(local_id);
1124+
let opt_fn_decl = FnLikeNode::from_node(self.tcx.map.get(parent))
1125+
.map(|fn_like| fn_like.decl());
1126+
1127+
if let Some(fn_decl) = opt_fn_decl {
1128+
if let Some(ref arg) = fn_decl.inputs.iter()
1129+
.find(|ref arg| arg.pat.id == local_id) {
1130+
if let hir::TyRptr(
1131+
opt_lifetime,
1132+
hir::MutTy{mutbl: hir::Mutability::MutImmutable, ref ty}) =
1133+
arg.ty.node {
1134+
if let Some(lifetime) = opt_lifetime {
1135+
if let Ok(snippet) = self.tcx.sess.codemap()
1136+
.span_to_snippet(ty.span) {
1137+
if let Ok(lifetime_snippet) = self.tcx.sess.codemap()
1138+
.span_to_snippet(lifetime.span) {
1139+
db.span_label(arg.ty.span,
1140+
&format!("use `&{} mut {}` \
1141+
here to make mutable",
1142+
lifetime_snippet,
1143+
snippet));
1144+
}
1145+
}
1146+
}
1147+
else if let Ok(snippet) = self.tcx.sess.codemap()
1148+
.span_to_snippet(arg.ty.span) {
1149+
if snippet.starts_with("&") {
1150+
db.span_label(arg.ty.span,
1151+
&format!("use `{}` here to make mutable",
1152+
snippet.replace("&", "&mut ")));
1153+
}
1154+
}
1155+
}
1156+
}
1157+
}
1158+
}
1159+
} else if let Categorization::Local(local_id) = err.cmt.cat {
1160+
let span = self.tcx.map.span(local_id);
1161+
if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
1162+
if snippet.starts_with("ref mut ") || snippet.starts_with("&mut ") {
1163+
db.span_label(*error_span, &format!("cannot reborrow mutably"));
1164+
db.span_label(*error_span, &format!("try removing `&mut` here"));
1165+
} else {
1166+
if snippet.starts_with("ref ") {
1167+
db.span_label(span, &format!("use `{}` here to make mutable",
1168+
snippet.replace("ref ", "ref mut ")));
1169+
} else if snippet != "self" {
1170+
db.span_label(span,
1171+
&format!("use `mut {}` here to make mutable",
1172+
snippet));
1173+
}
1174+
db.span_label(*error_span, &format!("cannot borrow mutably"));
1175+
}
1176+
} else {
1177+
db.span_label(*error_span, &format!("cannot borrow mutably"));
1178+
}
1179+
}
1180+
}
1181+
}
1182+
}
11461183
pub fn append_loan_path_to_string(&self,
11471184
loan_path: &LoanPath<'tcx>,
11481185
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

Lines changed: 86 additions & 0 deletions
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

Lines changed: 34 additions & 0 deletions
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

Lines changed: 43 additions & 0 deletions
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

Lines changed: 11 additions & 0 deletions
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.

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