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Suggest type param when encountering _ in item signatures #67597

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Merged
merged 8 commits into from
Dec 31, 2019
Merged

Suggest type param when encountering _ in item signatures #67597

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8cb193a
Suggest type param when encountering `_` in fn defs
estebank Dec 23, 2019
6c8b2dc
Account for all item kinds when collecting and gateing `_` in item defs
estebank Dec 24, 2019
fb52883
Account for existing type params when suggesting replacing `_` for a …
estebank Dec 24, 2019
3a9c3f9
Format and fix rebase
estebank Dec 26, 2019
e843245
review comments
estebank Dec 26, 2019
cfa0b07
clean up logic
estebank Dec 27, 2019
8a3872e
review comments
estebank Dec 27, 2019
261b606
review comments and fix rebase
estebank Dec 30, 2019
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Account for existing type params when suggesting replacing _ for a … 
…new one
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@estebank
estebank committed Dec 30, 2019
commit fb52883690831a0bbb8b97d75eadc696dd2fd422
25 changes: 22 additions & 3 deletions src/librustc_typeck/collect.rs
View file
Original file line number Diff line number Diff line change
@@ -134,11 +134,30 @@ crate fn placeholder_type_error(
suggest: bool,
) {
if !placeholder_types.is_empty() {
let mut sugg: Vec<_> = placeholder_types.iter().map(|sp| (*sp, "T".to_string())).collect();
let possible_names = ["T", "K", "L", "A", "B", "C"];
let used_names = generics.iter().filter_map(|p| match p.name {
hir::ParamName::Plain(ident) => Some(ident.name),
_ => None,
}).collect::<Vec<_>>();

let mut type_name = "ParamName";
for name in &possible_names {
if !used_names.contains(&Symbol::intern(name)) {
type_name = name;
break;
}
}

let mut sugg: Vec<_> = placeholder_types.iter()
.map(|sp| (*sp, type_name.to_string()))
.collect();
if generics.is_empty() {
sugg.push((ident_span.shrink_to_hi(), "<T>".to_string()));
sugg.push((ident_span.shrink_to_hi(), format!("<{}>", type_name)));
} else {
sugg.push((generics.iter().last().unwrap().span.shrink_to_hi(), ", T".to_string()));
sugg.push((
generics.iter().last().unwrap().span.shrink_to_hi(),
format!(", {}", type_name),
));
}
let mut err = struct_span_err!(
tcx.sess,
6 changes: 6 additions & 0 deletions src/test/ui/typeck/typeck_type_placeholder_item.rs
View file
Original file line number Diff line number Diff line change
@@ -19,6 +19,12 @@ static TEST5: (_, _) = (1, 2);
fn test6(_: _) { }
//~^ ERROR the type placeholder `_` is not allowed within types on item signatures

fn test6_b<T>(_: _, _: T) { }
//~^ ERROR the type placeholder `_` is not allowed within types on item signatures

fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
//~^ ERROR the type placeholder `_` is not allowed within types on item signatures

fn test7(x: _) { let _x: usize = x; }
//~^ ERROR the type placeholder `_` is not allowed within types on item signatures

84 changes: 53 additions & 31 deletions src/test/ui/typeck/typeck_type_placeholder_item.stderr
View file
Original file line number Diff line number Diff line change
@@ -54,7 +54,29 @@ LL | fn test6<T>(_: T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:22:13
--> $DIR/typeck_type_placeholder_item.rs:22:18
|
LL | fn test6_b<T>(_: _, _: T) { }
| ^ not allowed in type signatures
|
help: use type parameters instead
|
LL | fn test6_b<T, K>(_: K, _: T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:25:30
|
LL | fn test6_c<T, K, L, A, B>(_: _, _: (T, K, L, A, B)) { }
| ^ not allowed in type signatures
|
help: use type parameters instead
|
LL | fn test6_c<T, K, L, A, B, C>(_: C, _: (T, K, L, A, B)) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:28:13
|
LL | fn test7(x: _) { let _x: usize = x; }
| ^ not allowed in type signatures
@@ -65,7 +87,7 @@ LL | fn test7<T>(x: T) { let _x: usize = x; }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:25:22
--> $DIR/typeck_type_placeholder_item.rs:31:22
|
LL | fn test8(_f: fn() -> _) { }
| ^ not allowed in type signatures
@@ -76,7 +98,7 @@ LL | fn test8<T>(_f: fn() -> T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:47:8
--> $DIR/typeck_type_placeholder_item.rs:53:8
|
LL | a: _,
| ^ not allowed in type signatures
@@ -95,7 +117,7 @@ LL | b: (T, T),
|

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:53:21
--> $DIR/typeck_type_placeholder_item.rs:59:21
|
LL | fn fn_test() -> _ { 5 }
| ^
@@ -104,7 +126,7 @@ LL | fn fn_test() -> _ { 5 }
| help: replace this with the correct return type: `i32`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:56:22
--> $DIR/typeck_type_placeholder_item.rs:62:22
|
LL | fn fn_test2() -> (_, _) { (5, 5) }
| ^^^^^^
@@ -113,7 +135,7 @@ LL | fn fn_test2() -> (_, _) { (5, 5) }
| help: replace this with the correct return type: `(i32, i32)`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:59:22
--> $DIR/typeck_type_placeholder_item.rs:65:22
|
LL | static FN_TEST3: _ = "test";
| ^
@@ -122,7 +144,7 @@ LL | static FN_TEST3: _ = "test";
| help: replace `_` with the correct type: `&'static str`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:62:22
--> $DIR/typeck_type_placeholder_item.rs:68:22
|
LL | static FN_TEST4: _ = 145;
| ^
@@ -131,15 +153,15 @@ LL | static FN_TEST4: _ = 145;
| help: replace `_` with the correct type: `i32`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:65:23
--> $DIR/typeck_type_placeholder_item.rs:71:23
|
LL | static FN_TEST5: (_, _) = (1, 2);
| ^ ^ not allowed in type signatures
| |
| not allowed in type signatures

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:68:20
--> $DIR/typeck_type_placeholder_item.rs:74:20
|
LL | fn fn_test6(_: _) { }
| ^ not allowed in type signatures
@@ -150,7 +172,7 @@ LL | fn fn_test6<T>(_: T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:71:20
--> $DIR/typeck_type_placeholder_item.rs:77:20
|
LL | fn fn_test7(x: _) { let _x: usize = x; }
| ^ not allowed in type signatures
@@ -161,7 +183,7 @@ LL | fn fn_test7<T>(x: T) { let _x: usize = x; }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:74:29
--> $DIR/typeck_type_placeholder_item.rs:80:29
|
LL | fn fn_test8(_f: fn() -> _) { }
| ^ not allowed in type signatures
@@ -172,7 +194,7 @@ LL | fn fn_test8<T>(_f: fn() -> T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:96:12
--> $DIR/typeck_type_placeholder_item.rs:102:12
|
LL | a: _,
| ^ not allowed in type signatures
@@ -191,19 +213,19 @@ LL | b: (T, T),
|

error[E0282]: type annotations needed
--> $DIR/typeck_type_placeholder_item.rs:101:27
--> $DIR/typeck_type_placeholder_item.rs:107:27
|
LL | fn fn_test11(_: _) -> (_, _) { panic!() }
| ^^^^^^ cannot infer type

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:101:27
--> $DIR/typeck_type_placeholder_item.rs:107:27
|
LL | fn fn_test11(_: _) -> (_, _) { panic!() }
| ^^^^^^ not allowed in type signatures

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:105:29
--> $DIR/typeck_type_placeholder_item.rs:111:29
|
LL | fn fn_test12(x: i32) -> (_, _) { (x, x) }
| ^^^^^^
@@ -212,7 +234,7 @@ LL | fn fn_test12(x: i32) -> (_, _) { (x, x) }
| help: replace this with the correct return type: `(i32, i32)`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:108:21
--> $DIR/typeck_type_placeholder_item.rs:114:21
|
LL | fn fn_test13(x: _) -> (i32, _) { (x, x) }
| ^ ^ not allowed in type signatures
@@ -225,7 +247,7 @@ LL | fn fn_test13<T>(x: T) -> (i32, T) { (x, x) }
| ^^^ ^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:113:31
--> $DIR/typeck_type_placeholder_item.rs:119:31
|
LL | fn method_test1(&self, x: _);
| ^ not allowed in type signatures
@@ -236,7 +258,7 @@ LL | fn method_test1<T>(&self, x: T);
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:115:31
--> $DIR/typeck_type_placeholder_item.rs:121:31
|
LL | fn method_test2(&self, x: _) -> _;
| ^ ^ not allowed in type signatures
@@ -249,7 +271,7 @@ LL | fn method_test2<T>(&self, x: T) -> T;
| ^^^ ^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:117:31
--> $DIR/typeck_type_placeholder_item.rs:123:31
|
LL | fn method_test3(&self) -> _;
| ^ not allowed in type signatures
@@ -260,7 +282,7 @@ LL | fn method_test3<T>(&self) -> T;
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:119:26
--> $DIR/typeck_type_placeholder_item.rs:125:26
|
LL | fn assoc_fn_test1(x: _);
| ^ not allowed in type signatures
@@ -271,7 +293,7 @@ LL | fn assoc_fn_test1<T>(x: T);
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:121:26
--> $DIR/typeck_type_placeholder_item.rs:127:26
|
LL | fn assoc_fn_test2(x: _) -> _;
| ^ ^ not allowed in type signatures
@@ -284,7 +306,7 @@ LL | fn assoc_fn_test2<T>(x: T) -> T;
| ^^^ ^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:123:28
--> $DIR/typeck_type_placeholder_item.rs:129:28
|
LL | fn assoc_fn_test3() -> _;
| ^ not allowed in type signatures
@@ -295,7 +317,7 @@ LL | fn assoc_fn_test3<T>() -> T;
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:31:24
--> $DIR/typeck_type_placeholder_item.rs:37:24
|
LL | fn test9(&self) -> _ { () }
| ^
@@ -304,7 +326,7 @@ LL | fn test9(&self) -> _ { () }
| help: replace this with the correct return type: `()`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:34:27
--> $DIR/typeck_type_placeholder_item.rs:40:27
|
LL | fn test10(&self, _x : _) { }
| ^ not allowed in type signatures
@@ -315,7 +337,7 @@ LL | fn test10<T>(&self, _x : T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:39:24
--> $DIR/typeck_type_placeholder_item.rs:45:24
|
LL | fn clone(&self) -> _ { Test9 }
| ^
@@ -324,7 +346,7 @@ LL | fn clone(&self) -> _ { Test9 }
| help: replace this with the correct return type: `Test9`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:42:37
--> $DIR/typeck_type_placeholder_item.rs:48:37
|
LL | fn clone_from(&mut self, other: _) { *self = Test9; }
| ^ not allowed in type signatures
@@ -335,7 +357,7 @@ LL | fn clone_from<T>(&mut self, other: T) { *self = Test9; }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:80:31
--> $DIR/typeck_type_placeholder_item.rs:86:31
|
LL | fn fn_test9(&self) -> _ { () }
| ^
@@ -344,7 +366,7 @@ LL | fn fn_test9(&self) -> _ { () }
| help: replace this with the correct return type: `()`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:83:34
--> $DIR/typeck_type_placeholder_item.rs:89:34
|
LL | fn fn_test10(&self, _x : _) { }
| ^ not allowed in type signatures
@@ -355,7 +377,7 @@ LL | fn fn_test10<T>(&self, _x : T) { }
| ^^^ ^

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:88:28
--> $DIR/typeck_type_placeholder_item.rs:94:28
|
LL | fn clone(&self) -> _ { FnTest9 }
| ^
@@ -364,7 +386,7 @@ LL | fn clone(&self) -> _ { FnTest9 }
| help: replace this with the correct return type: `main::FnTest9`

error[E0121]: the type placeholder `_` is not allowed within types on item signatures
--> $DIR/typeck_type_placeholder_item.rs:91:41
--> $DIR/typeck_type_placeholder_item.rs:97:41
|
LL | fn clone_from(&mut self, other: _) { *self = FnTest9; }
| ^ not allowed in type signatures
@@ -374,7 +396,7 @@ help: use type parameters instead
LL | fn clone_from<T>(&mut self, other: T) { *self = FnTest9; }
| ^^^ ^

error: aborting due to 36 previous errors
error: aborting due to 38 previous errors

Some errors have detailed explanations: E0121, E0282.
For more information about an error, try `rustc --explain E0121`.