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Account for existing type params when suggesting replacing _ for a new one

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This commit is contained in:
Esteban Küber 2019-12-24 15:12:01 -08:00
parent 6c8b2dcb19
commit fb52883690
3 changed files with 81 additions and 34 deletions
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25
src/librustc_typeck/collect.rs
View file

@ -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
src/test/ui/typeck/typeck_type_placeholder_item.rs
View file

@ -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
src/test/ui/typeck/typeck_type_placeholder_item.stderr
View file

@ -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;
| ^
@ -131,7 +153,7 @@ 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
@ -139,7 +161,7 @@ LL | static FN_TEST5: (_, _) = (1, 2);
| 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`.