Make spans for tuple patterns in E0023 more precise

As suggested in rust-lang#86307.
camelid · Aug 17, 2021 · da25af2 · da25af2
1 parent d83da1d
commit da25af2
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Showing 10 changed files with 96 additions and 48 deletions.
diff --git a/compiler/rustc_typeck/src/check/pat.rs b/compiler/rustc_typeck/src/check/pat.rs
@@ -990,10 +990,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     ) {
         let subpats_ending = pluralize!(subpats.len());
         let fields_ending = pluralize!(fields.len());
+        let fields_span = pat_span.trim_start(qpath.span()).unwrap_or(pat_span);
         let res_span = self.tcx.def_span(res.def_id());
         let mut err = struct_span_err!(
             self.tcx.sess,
-            pat_span,
+            fields_span,
             E0023,
             "this pattern has {} field{}, but the corresponding {} has {} field{}",
             subpats.len(),
@@ -1003,9 +1004,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             fields_ending,
         );
         err.span_label(
-            pat_span,
+            fields_span,
             format!("expected {} field{}, found {}", fields.len(), fields_ending, subpats.len(),),
         )
+        .span_label(qpath.span(), format!("this {}", res.descr()))
         .span_label(res_span, format!("{} defined here", res.descr()));
 
         // Identify the case `Some(x, y)` where the expected type is e.g. `Option<(T, U)>`.

diff --git a/src/test/ui/destructuring-assignment/tuple_struct_destructure_fail.stderr b/src/test/ui/destructuring-assignment/tuple_struct_destructure_fail.stderr
@@ -15,22 +15,26 @@ LL |     Enum::SingleVariant(a, .., b, ..) = Enum::SingleVariant(0, 1);
    |                            previously used here
 
 error[E0023]: this pattern has 3 fields, but the corresponding tuple struct has 2 fields
-  --> $DIR/tuple_struct_destructure_fail.rs:30:5
+  --> $DIR/tuple_struct_destructure_fail.rs:30:16
    |
 LL | struct TupleStruct<S, T>(S, T);
    | ------------------------------- tuple struct defined here
 ...
 LL |     TupleStruct(a, a, b) = TupleStruct(1, 2);
-   |     ^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 3
+   |     -----------^^^^^^^^^ expected 2 fields, found 3
+   |     |
+   |     this tuple struct
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple struct has 2 fields
-  --> $DIR/tuple_struct_destructure_fail.rs:32:5
+  --> $DIR/tuple_struct_destructure_fail.rs:32:16
    |
 LL | struct TupleStruct<S, T>(S, T);
    | ------------------------------- tuple struct defined here
 ...
 LL |     TupleStruct(_) = TupleStruct(1, 2);
-   |     ^^^^^^^^^^^^^^ expected 2 fields, found 1
+   |     -----------^^^ expected 2 fields, found 1
+   |     |
+   |     this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |
@@ -42,22 +46,26 @@ LL |     TupleStruct(..) = TupleStruct(1, 2);
    |                 ~~
 
 error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 2 fields
-  --> $DIR/tuple_struct_destructure_fail.rs:34:5
+  --> $DIR/tuple_struct_destructure_fail.rs:34:24
    |
 LL |     SingleVariant(S, T)
    |     ------------------- tuple variant defined here
 ...
 LL |     Enum::SingleVariant(a, a, b) = Enum::SingleVariant(1, 2);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 3
+   |     -------------------^^^^^^^^^ expected 2 fields, found 3
+   |     |
+   |     this tuple variant
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
-  --> $DIR/tuple_struct_destructure_fail.rs:36:5
+  --> $DIR/tuple_struct_destructure_fail.rs:36:24
    |
 LL |     SingleVariant(S, T)
    |     ------------------- tuple variant defined here
 ...
 LL |     Enum::SingleVariant(_) = Enum::SingleVariant(1, 2);
-   |     ^^^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 1
+   |     -------------------^^^ expected 2 fields, found 1
+   |     |
+   |     this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |

diff --git a/src/test/ui/error-codes/E0023.stderr b/src/test/ui/error-codes/E0023.stderr
@@ -1,57 +1,67 @@
 error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
-  --> $DIR/E0023.rs:11:9
+  --> $DIR/E0023.rs:11:21
    |
 LL |     Apple(String, String),
    |     --------------------- tuple variant defined here
 ...
 LL |         Fruit::Apple(a) => {},
-   |         ^^^^^^^^^^^^^^^ expected 2 fields, found 1
+   |         ------------^^^ expected 2 fields, found 1
+   |         |
+   |         this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |
 LL |         Fruit::Apple(a, _) => {},
    |                       +++
 
 error[E0023]: this pattern has 3 fields, but the corresponding tuple variant has 2 fields
-  --> $DIR/E0023.rs:12:9
+  --> $DIR/E0023.rs:12:21
    |
 LL |     Apple(String, String),
    |     --------------------- tuple variant defined here
 ...
 LL |         Fruit::Apple(a, b, c) => {},
-   |         ^^^^^^^^^^^^^^^^^^^^^ expected 2 fields, found 3
+   |         ------------^^^^^^^^^ expected 2 fields, found 3
+   |         |
+   |         this tuple variant
 
 error[E0023]: this pattern has 2 fields, but the corresponding tuple variant has 1 field
-  --> $DIR/E0023.rs:13:9
+  --> $DIR/E0023.rs:13:20
    |
 LL |     Pear(u32),
    |     --------- tuple variant defined here
 ...
 LL |         Fruit::Pear(1, 2) => {},
-   |         ^^^^^^^^^^^^^^^^^ expected 1 field, found 2
+   |         -----------^^^^^^ expected 1 field, found 2
+   |         |
+   |         this tuple variant
 
 error[E0023]: this pattern has 2 fields, but the corresponding tuple variant has 1 field
-  --> $DIR/E0023.rs:14:9
+  --> $DIR/E0023.rs:14:22
    |
 LL |     Orange((String, String)),
    |     ------------------------ tuple variant defined here
 ...
 LL |         Fruit::Orange(a, b) => {},
-   |         ^^^^^^^^^^^^^^^^^^^ expected 1 field, found 2
+   |         -------------^^^^^^ expected 1 field, found 2
+   |         |
+   |         this tuple variant
    |
 help: missing parentheses
    |
 LL |         Fruit::Orange((a, b)) => {},
    |                       +    +
 
 error[E0023]: this pattern has 0 fields, but the corresponding tuple variant has 1 field
-  --> $DIR/E0023.rs:15:9
+  --> $DIR/E0023.rs:15:22
    |
 LL |     Banana(()),
    |     ---------- tuple variant defined here
 ...
 LL |         Fruit::Banana() => {},
-   |         ^^^^^^^^^^^^^^^ expected 1 field, found 0
+   |         -------------^^ expected 1 field, found 0
+   |         |
+   |         this tuple variant
    |
 help: missing parentheses
    |

diff --git a/src/test/ui/issues/issue-72574-2.stderr b/src/test/ui/issues/issue-72574-2.stderr
@@ -19,13 +19,15 @@ LL |         Binder(_a, _x @ ..) => {}
    = note: only allowed in tuple, tuple struct, and slice patterns
 
 error[E0023]: this pattern has 2 fields, but the corresponding tuple struct has 3 fields
-  --> $DIR/issue-72574-2.rs:6:9
+  --> $DIR/issue-72574-2.rs:6:15
    |
 LL | struct Binder(i32, i32, i32);
    | ----------------------------- tuple struct defined here
 ...
 LL |         Binder(_a, _x @ ..) => {}
-   |         ^^^^^^^^^^^^^^^^^^^ expected 3 fields, found 2
+   |         ------^^^^^^^^^^^^^ expected 3 fields, found 2
+   |         |
+   |         this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |

diff --git a/src/test/ui/match/match-pattern-field-mismatch.stderr b/src/test/ui/match/match-pattern-field-mismatch.stderr
@@ -1,11 +1,13 @@
 error[E0023]: this pattern has 2 fields, but the corresponding tuple variant has 3 fields
-  --> $DIR/match-pattern-field-mismatch.rs:10:11
+  --> $DIR/match-pattern-field-mismatch.rs:10:21
    |
 LL |         Rgb(usize, usize, usize),
    |         ------------------------ tuple variant defined here
 ...
 LL |           Color::Rgb(_, _) => { }
-   |           ^^^^^^^^^^^^^^^^ expected 3 fields, found 2
+   |           ----------^^^^^^ expected 3 fields, found 2
+   |           |
+   |           this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |

diff --git a/src/test/ui/pattern/issue-67037-pat-tup-scrut-ty-diff-less-fields.stderr b/src/test/ui/pattern/issue-67037-pat-tup-scrut-ty-diff-less-fields.stderr
@@ -10,13 +10,15 @@ LL |     let P() = U {};
               found struct `P<_>`
 
 error[E0023]: this pattern has 0 fields, but the corresponding tuple struct has 1 field
-  --> $DIR/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs:19:9
+  --> $DIR/issue-67037-pat-tup-scrut-ty-diff-less-fields.rs:19:10
    |
 LL | struct P<T>(T); // 1 type parameter wanted
    | --------------- tuple struct defined here
 ...
 LL |     let P() = U {};
-   |         ^^^ expected 1 field, found 0
+   |         -^^ expected 1 field, found 0
+   |         |
+   |         this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |

diff --git a/src/test/ui/pattern/issue-74539.stderr b/src/test/ui/pattern/issue-74539.stderr
@@ -19,13 +19,15 @@ LL |         E::A(x @ ..) => {
    = note: only allowed in tuple, tuple struct, and slice patterns
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
-  --> $DIR/issue-74539.rs:8:9
+  --> $DIR/issue-74539.rs:8:13
    |
 LL |     A(u8, u8),
    |     --------- tuple variant defined here
 ...
 LL |         E::A(x @ ..) => {
-   |         ^^^^^^^^^^^^ expected 2 fields, found 1
+   |         ----^^^^^^^^ expected 2 fields, found 1
+   |         |
+   |         this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |

diff --git a/src/test/ui/pattern/pat-tuple-overfield.stderr b/src/test/ui/pattern/pat-tuple-overfield.stderr
@@ -22,22 +22,26 @@ LL |         (1, 2, .., 3, 4) => {}
               found tuple `(_, _, _, _)`
 
 error[E0023]: this pattern has 4 fields, but the corresponding tuple struct has 3 fields
-  --> $DIR/pat-tuple-overfield.rs:10:9
+  --> $DIR/pat-tuple-overfield.rs:10:10
    |
 LL | struct S(u8, u8, u8);
    | --------------------- tuple struct defined here
 ...
 LL |         S(1, 2, 3, 4) => {}
-   |         ^^^^^^^^^^^^^ expected 3 fields, found 4
+   |         -^^^^^^^^^^^^ expected 3 fields, found 4
+   |         |
+   |         this tuple struct
 
 error[E0023]: this pattern has 4 fields, but the corresponding tuple struct has 3 fields
-  --> $DIR/pat-tuple-overfield.rs:12:9
+  --> $DIR/pat-tuple-overfield.rs:12:10
    |
 LL | struct S(u8, u8, u8);
    | --------------------- tuple struct defined here
 ...
 LL |         S(1, 2, .., 3, 4) => {}
-   |         ^^^^^^^^^^^^^^^^^ expected 3 fields, found 4
+   |         -^^^^^^^^^^^^^^^^ expected 3 fields, found 4
+   |         |
+   |         this tuple struct
 
 error: aborting due to 4 previous errors
 

diff --git a/src/test/ui/pattern/pat-tuple-underfield.stderr b/src/test/ui/pattern/pat-tuple-underfield.stderr
@@ -8,27 +8,31 @@ LL |         E::S => {}
    |         ^^^^ help: use the tuple variant pattern syntax instead: `E::S(_, _)`
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple struct has 2 fields
-  --> $DIR/pat-tuple-underfield.rs:9:9
+  --> $DIR/pat-tuple-underfield.rs:9:10
    |
 LL | struct S(i32, f32);
    | ------------------- tuple struct defined here
 ...
 LL |         S(x) => {}
-   |         ^^^^ expected 2 fields, found 1
+   |         -^^^ expected 2 fields, found 1
+   |         |
+   |         this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |
 LL |         S(x, _) => {}
    |            +++
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple struct has 2 fields
-  --> $DIR/pat-tuple-underfield.rs:14:9
+  --> $DIR/pat-tuple-underfield.rs:14:10
    |
 LL | struct S(i32, f32);
    | ------------------- tuple struct defined here
 ...
 LL |         S(_) => {}
-   |         ^^^^ expected 2 fields, found 1
+   |         -^^^ expected 2 fields, found 1
+   |         |
+   |         this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |
@@ -40,13 +44,15 @@ LL |         S(..) => {}
    |           ~~
 
 error[E0023]: this pattern has 0 fields, but the corresponding tuple struct has 2 fields
-  --> $DIR/pat-tuple-underfield.rs:20:9
+  --> $DIR/pat-tuple-underfield.rs:20:10
    |
 LL | struct S(i32, f32);
    | ------------------- tuple struct defined here
 ...
 LL |         S() => {}
-   |         ^^^ expected 2 fields, found 0
+   |         -^^ expected 2 fields, found 0
+   |         |
+   |         this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |
@@ -58,27 +64,31 @@ LL |         S(..) => {}
    |           ++
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
-  --> $DIR/pat-tuple-underfield.rs:27:9
+  --> $DIR/pat-tuple-underfield.rs:27:13
    |
 LL |     S(i32, f32),
    |     ----------- tuple variant defined here
 ...
 LL |         E::S(x) => {}
-   |         ^^^^^^^ expected 2 fields, found 1
+   |         ----^^^ expected 2 fields, found 1
+   |         |
+   |         this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |
 LL |         E::S(x, _) => {}
    |               +++
 
 error[E0023]: this pattern has 1 field, but the corresponding tuple variant has 2 fields
-  --> $DIR/pat-tuple-underfield.rs:32:9
+  --> $DIR/pat-tuple-underfield.rs:32:13
    |
 LL |     S(i32, f32),
    |     ----------- tuple variant defined here
 ...
 LL |         E::S(_) => {}
-   |         ^^^^^^^ expected 2 fields, found 1
+   |         ----^^^ expected 2 fields, found 1
+   |         |
+   |         this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |
@@ -90,13 +100,15 @@ LL |         E::S(..) => {}
    |              ~~
 
 error[E0023]: this pattern has 0 fields, but the corresponding tuple variant has 2 fields
-  --> $DIR/pat-tuple-underfield.rs:38:9
+  --> $DIR/pat-tuple-underfield.rs:38:13
    |
 LL |     S(i32, f32),
    |     ----------- tuple variant defined here
 ...
 LL |         E::S() => {}
-   |         ^^^^^^ expected 2 fields, found 0
+   |         ----^^ expected 2 fields, found 0
+   |         |
+   |         this tuple variant
    |
 help: use `_` to explicitly ignore each field
    |
@@ -108,13 +120,15 @@ LL |         E::S(..) => {}
    |              ++
 
 error[E0023]: this pattern has 2 fields, but the corresponding tuple struct has 4 fields
-  --> $DIR/pat-tuple-underfield.rs:50:9
+  --> $DIR/pat-tuple-underfield.rs:50:15
    |
 LL | struct Point4(i32, i32, i32, i32);
    | ---------------------------------- tuple struct defined here
 ...
 LL |         Point4(   a   ,     _    ) => {}
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ expected 4 fields, found 2
+   |         ------^^^^^^^^^^^^^^^^^^^^ expected 4 fields, found 2
+   |         |
+   |         this tuple struct
    |
 help: use `_` to explicitly ignore each field
    |