Rollup merge of #66014 - dkadashev:47319-type-param-def-location, r=e…

…stebank Show type parameter name and definition in type mismatch error messages Fixes #47319 r? estebank
rust-lang · Nov 6, 2019 · f746d99 · f746d99
2 parents 5910116 + 774e60b
commit f746d99
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Showing 21 changed files with 141 additions and 44 deletions.
diff --git a/src/librustc/infer/error_reporting/mod.rs b/src/librustc/infer/error_reporting/mod.rs
@@ -1234,8 +1234,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             }
         }
 
+        // In some (most?) cases cause.body_id points to actual body, but in some cases
+        // it's a actual definition. According to the comments (e.g. in
+        // librustc_typeck/check/compare_method.rs:compare_predicate_entailment) the latter
+        // is relied upon by some other code. This might (or might not) need cleanup.
+        let body_owner_def_id = self.tcx.hir().opt_local_def_id(cause.body_id)
+            .unwrap_or_else(|| {
+                self.tcx.hir().body_owner_def_id(hir::BodyId { hir_id: cause.body_id })
+            });
         self.check_and_note_conflicting_crates(diag, terr, span);
-        self.tcx.note_and_explain_type_err(diag, terr, span);
+        self.tcx.note_and_explain_type_err(diag, terr, span, body_owner_def_id);
 
         // It reads better to have the error origin as the final
         // thing.

diff --git a/src/librustc/ty/error.rs b/src/librustc/ty/error.rs
@@ -241,7 +241,7 @@ impl<'tcx> ty::TyS<'tcx> {
             ty::Infer(ty::FreshFloatTy(_)) => "fresh floating-point type".into(),
             ty::Projection(_) => "associated type".into(),
             ty::UnnormalizedProjection(_) => "non-normalized associated type".into(),
-            ty::Param(_) => "type parameter".into(),
+            ty::Param(p) => format!("type parameter `{}`", p).into(),
             ty::Opaque(..) => "opaque type".into(),
             ty::Error => "type error".into(),
         }
@@ -254,6 +254,7 @@ impl<'tcx> TyCtxt<'tcx> {
         db: &mut DiagnosticBuilder<'_>,
         err: &TypeError<'tcx>,
         sp: Span,
+        body_owner_def_id: DefId,
     ) {
         use self::TypeError::*;
 
@@ -288,7 +289,16 @@ impl<'tcx> TyCtxt<'tcx> {
                             );
                         }
                     },
-                    (ty::Param(_), ty::Param(_)) => {
+                    (ty::Param(expected), ty::Param(found)) => {
+                        let generics = self.generics_of(body_owner_def_id);
+                        let e_span = self.def_span(generics.type_param(expected, self).def_id);
+                        if !sp.contains(e_span) {
+                            db.span_label(e_span, "expected type parameter");
+                        }
+                        let f_span = self.def_span(generics.type_param(found, self).def_id);
+                        if !sp.contains(f_span) {
+                            db.span_label(f_span, "found type parameter");
+                        }
                         db.note("a type parameter was expected, but a different one was found; \
                                  you might be missing a type parameter or trait bound");
                         db.note("for more information, visit \
@@ -301,7 +311,12 @@ impl<'tcx> TyCtxt<'tcx> {
                     (ty::Param(_), ty::Projection(_)) | (ty::Projection(_), ty::Param(_)) => {
                         db.note("you might be missing a type parameter or trait bound");
                     }
-                    (ty::Param(_), _) | (_, ty::Param(_)) => {
+                    (ty::Param(p), _) | (_, ty::Param(p)) => {
+                        let generics = self.generics_of(body_owner_def_id);
+                        let p_span = self.def_span(generics.type_param(p, self).def_id);
+                        if !sp.contains(p_span) {
+                            db.span_label(p_span, "this type parameter");
+                        }
                         db.help("type parameters must be constrained to match other types");
                         if self.sess.teach(&db.get_code().unwrap()) {
                             db.help("given a type parameter `T` and a method `foo`:

diff --git a/src/test/ui/associated-types/associated-types-issue-20346.stderr b/src/test/ui/associated-types/associated-types-issue-20346.stderr
@@ -4,8 +4,11 @@ error[E0271]: type mismatch resolving `<Adapter<I> as Iterator>::Item == std::op
 LL | fn is_iterator_of<A, I: Iterator<Item=A>>(_: &I) {}
    |    --------------                ------ required by this bound in `is_iterator_of`
 ...
+LL | fn test_adapter<T, I: Iterator<Item=Option<T>>>(it: I) {
+   |                 - this type parameter
+...
 LL |     is_iterator_of::<Option<T>, _>(&adapter);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `std::option::Option`, found type parameter
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `std::option::Option`, found type parameter `T`
    |
    = note: expected type `std::option::Option<T>`
               found type `T`

diff --git a/src/test/ui/compare-method/reordered-type-param.stderr b/src/test/ui/compare-method/reordered-type-param.stderr
@@ -5,7 +5,10 @@ LL |   fn b<C:Clone,D>(&self, x: C) -> C;
    |                             - type in trait
 ...
 LL |   fn b<F:Clone,G>(&self, _x: G) -> G { panic!() }
-   |                              ^ expected type parameter, found a different type parameter
+   |        -       -             ^ expected type parameter `F`, found type parameter `G`
+   |        |       |
+   |        |       found type parameter
+   |        expected type parameter
    |
    = note: expected type `fn(&E, F) -> F`
               found type `fn(&E, G) -> G`

diff --git a/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr b/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr
@@ -5,7 +5,9 @@ LL |     fn foo<A: Debug>(&self, a: &A, b: &impl Debug);
    |                                -- type in trait
 ...
 LL |     fn foo<B: Debug>(&self, a: &impl Debug, b: &B) { }
-   |                                ^^^^^^^^^^^ expected type parameter, found a different type parameter
+   |            -                   ^^^^^^^^^^^ expected type parameter `B`, found type parameter `impl Debug`
+   |            |
+   |            expected type parameter
    |
    = note: expected type `fn(&(), &B, &impl Debug)`
               found type `fn(&(), &impl Debug, &B)`

diff --git a/src/test/ui/impl-trait/universal-mismatched-type.stderr b/src/test/ui/impl-trait/universal-mismatched-type.stderr
@@ -2,9 +2,11 @@ error[E0308]: mismatched types
   --> $DIR/universal-mismatched-type.rs:4:5
    |
 LL | fn foo(x: impl Debug) -> String {
-   |                          ------ expected `std::string::String` because of return type
+   |           ----------     ------ expected `std::string::String` because of return type
+   |           |
+   |           this type parameter
 LL |     x
-   |     ^ expected struct `std::string::String`, found type parameter
+   |     ^ expected struct `std::string::String`, found type parameter `impl Debug`
    |
    = note: expected type `std::string::String`
               found type `impl Debug`

diff --git a/src/test/ui/impl-trait/universal-two-impl-traits.stderr b/src/test/ui/impl-trait/universal-two-impl-traits.stderr
@@ -1,11 +1,16 @@
 error[E0308]: mismatched types
   --> $DIR/universal-two-impl-traits.rs:5:9
    |
+LL | fn foo(x: impl Debug, y: impl Debug) -> String {
+   |           ----------     ---------- found type parameter
+   |           |
+   |           expected type parameter
+LL |     let mut a = x;
 LL |     a = y;
-   |         ^ expected type parameter, found a different type parameter
+   |         ^ expected type parameter `impl Debug`, found a different type parameter `impl Debug`
    |
-   = note: expected type `impl Debug` (type parameter)
-              found type `impl Debug` (type parameter)
+   = note: expected type `impl Debug` (type parameter `impl Debug`)
+              found type `impl Debug` (type parameter `impl Debug`)
    = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound
    = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
 

diff --git a/src/test/ui/issues/issue-13853.stderr b/src/test/ui/issues/issue-13853.stderr
@@ -2,10 +2,10 @@ error[E0308]: mismatched types
   --> $DIR/issue-13853.rs:14:9
    |
 LL |     fn nodes<'a, I: Iterator<Item=&'a N>>(&self) -> I
-   |                                                     - expected `I` because of return type
+   |                  - this type parameter              - expected `I` because of return type
 ...
 LL |         self.iter()
-   |         ^^^^^^^^^^^ expected type parameter, found struct `std::slice::Iter`
+   |         ^^^^^^^^^^^ expected type parameter `I`, found struct `std::slice::Iter`
    |
    = note: expected type `I`
               found type `std::slice::Iter<'_, N>`

diff --git a/src/test/ui/issues/issue-20225.stderr b/src/test/ui/issues/issue-20225.stderr
@@ -1,8 +1,10 @@
 error[E0053]: method `call` has an incompatible type for trait
   --> $DIR/issue-20225.rs:6:3
    |
+LL | impl<'a, T> Fn<(&'a T,)> for Foo {
+   |          - this type parameter
 LL |   extern "rust-call" fn call(&self, (_,): (T,)) {}
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found type parameter
+   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found type parameter `T`
    |
    = note: expected type `extern "rust-call" fn(&Foo, (&'a T,))`
               found type `extern "rust-call" fn(&Foo, (T,))`
@@ -12,8 +14,10 @@ LL |   extern "rust-call" fn call(&self, (_,): (T,)) {}
 error[E0053]: method `call_mut` has an incompatible type for trait
   --> $DIR/issue-20225.rs:12:3
    |
+LL | impl<'a, T> FnMut<(&'a T,)> for Foo {
+   |          - this type parameter
 LL |   extern "rust-call" fn call_mut(&mut self, (_,): (T,)) {}
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found type parameter
+   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found type parameter `T`
    |
    = note: expected type `extern "rust-call" fn(&mut Foo, (&'a T,))`
               found type `extern "rust-call" fn(&mut Foo, (T,))`
@@ -23,8 +27,11 @@ LL |   extern "rust-call" fn call_mut(&mut self, (_,): (T,)) {}
 error[E0053]: method `call_once` has an incompatible type for trait
   --> $DIR/issue-20225.rs:20:3
    |
+LL | impl<'a, T> FnOnce<(&'a T,)> for Foo {
+   |          - this type parameter
+...
 LL |   extern "rust-call" fn call_once(self, (_,): (T,)) {}
-   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found type parameter
+   |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected reference, found type parameter `T`
    |
    = note: expected type `extern "rust-call" fn(Foo, (&'a T,))`
               found type `extern "rust-call" fn(Foo, (T,))`

diff --git a/src/test/ui/issues/issue-24204.stderr b/src/test/ui/issues/issue-24204.stderr
@@ -5,7 +5,7 @@ LL | trait Trait: Sized {
    | ------------------ required by `Trait`
 ...
 LL | fn test<T: Trait<B=i32>>(b: i32) -> T where T::A: MultiDispatch<i32> { T::new(b) }
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected type parameter, found associated type
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected type parameter `T`, found associated type
    |
    = note: expected type `T`
               found type `<<T as Trait>::A as MultiDispatch<i32>>::O`

diff --git a/src/test/ui/issues/issue-2951.rs b/src/test/ui/issues/issue-2951.rs
@@ -4,7 +4,7 @@ fn foo<T, U>(x: T, y: U) {
     //~^  ERROR mismatched types
     //~| expected type `T`
     //~| found type `U`
-    //~| expected type parameter, found a different type parameter
+    //~| expected type parameter `T`, found type parameter `U`
 }
 
 fn main() {

diff --git a/src/test/ui/issues/issue-2951.stderr b/src/test/ui/issues/issue-2951.stderr
@@ -1,8 +1,13 @@
 error[E0308]: mismatched types
   --> $DIR/issue-2951.rs:3:10
    |
+LL | fn foo<T, U>(x: T, y: U) {
+   |        -  - found type parameter
+   |        |
+   |        expected type parameter
+LL |     let mut xx = x;
 LL |     xx = y;
-   |          ^ expected type parameter, found a different type parameter
+   |          ^ expected type parameter `T`, found type parameter `U`
    |
    = note: expected type `T`
               found type `U`

diff --git a/src/test/ui/mismatched_types/issue-35030.stderr b/src/test/ui/mismatched_types/issue-35030.stderr
@@ -1,10 +1,13 @@
 error[E0308]: mismatched types
   --> $DIR/issue-35030.rs:9:14
    |
+LL | impl<bool> Parser<bool> for bool {
+   |      ---- this type parameter
+LL |     fn parse(text: &str) -> Option<bool> {
 LL |         Some(true)
-   |              ^^^^ expected type parameter, found bool
+   |              ^^^^ expected type parameter `bool`, found bool
    |
-   = note: expected type `bool` (type parameter)
+   = note: expected type `bool` (type parameter `bool`)
               found type `bool` (bool)
    = help: type parameters must be constrained to match other types
    = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters

diff --git a/src/test/ui/structs/struct-path-self-type-mismatch.stderr b/src/test/ui/structs/struct-path-self-type-mismatch.stderr
@@ -7,8 +7,13 @@ LL |         Self { inner: 1.5f32 };
 error[E0308]: mismatched types
   --> $DIR/struct-path-self-type-mismatch.rs:15:20
    |
+LL | impl<T> Foo<T> {
+   |      - expected type parameter
+LL |     fn new<U>(u: U) -> Foo<U> {
+   |            - found type parameter
+...
 LL |             inner: u
-   |                    ^ expected type parameter, found a different type parameter
+   |                    ^ expected type parameter `T`, found type parameter `U`
    |
    = note: expected type `T`
               found type `U`
@@ -18,14 +23,18 @@ LL |             inner: u
 error[E0308]: mismatched types
   --> $DIR/struct-path-self-type-mismatch.rs:13:9
    |
+LL |   impl<T> Foo<T> {
+   |        - found type parameter
 LL |       fn new<U>(u: U) -> Foo<U> {
-   |                          ------ expected `Foo<U>` because of return type
+   |              -           ------ expected `Foo<U>` because of return type
+   |              |
+   |              expected type parameter
 LL | /         Self {
 LL | |
 LL | |             inner: u
 LL | |
 LL | |         }
-   | |_________^ expected type parameter, found a different type parameter
+   | |_________^ expected type parameter `U`, found type parameter `T`
    |
    = note: expected type `Foo<U>`
               found type `Foo<T>`

diff --git a/src/test/ui/structs/struct-path-self.stderr b/src/test/ui/structs/struct-path-self.stderr
@@ -1,4 +1,4 @@
-error[E0071]: expected struct, variant or union type, found type parameter
+error[E0071]: expected struct, variant or union type, found type parameter `Self`
   --> $DIR/struct-path-self.rs:5:17
    |
 LL |         let s = Self {};
@@ -10,13 +10,13 @@ error[E0109]: type arguments are not allowed for this type
 LL |         let z = Self::<u8> {};
    |                        ^^ type argument not allowed
 
-error[E0071]: expected struct, variant or union type, found type parameter
+error[E0071]: expected struct, variant or union type, found type parameter `Self`
   --> $DIR/struct-path-self.rs:7:17
    |
 LL |         let z = Self::<u8> {};
    |                 ^^^^^^^^^^ not a struct
 
-error[E0071]: expected struct, variant or union type, found type parameter
+error[E0071]: expected struct, variant or union type, found type parameter `Self`
   --> $DIR/struct-path-self.rs:11:13
    |
 LL |             Self { .. } => {}

diff --git a/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr b/src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
@@ -1,8 +1,11 @@
 error[E0308]: mismatched types
   --> $DIR/enum-variant-generic-args.rs:13:25
    |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+LL |     fn ts_variant() {
 LL |         Self::TSVariant(());
-   |                         ^^ expected type parameter, found ()
+   |                         ^^ expected type parameter `T`, found ()
    |
    = note: expected type `T`
               found type `()`
@@ -24,8 +27,11 @@ LL |         Self::<()>::TSVariant(());
 error[E0308]: mismatched types
   --> $DIR/enum-variant-generic-args.rs:17:31
    |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
 LL |         Self::<()>::TSVariant(());
-   |                               ^^ expected type parameter, found ()
+   |                               ^^ expected type parameter `T`, found ()
    |
    = note: expected type `T`
               found type `()`
@@ -47,8 +53,11 @@ LL |         Self::<()>::TSVariant::<()>(());
 error[E0308]: mismatched types
   --> $DIR/enum-variant-generic-args.rs:26:29
    |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
 LL |         Self::SVariant { v: () };
-   |                             ^^ expected type parameter, found ()
+   |                             ^^ expected type parameter `T`, found ()
    |
    = note: expected type `T`
               found type `()`
@@ -64,8 +73,11 @@ LL |         Self::SVariant::<()> { v: () };
 error[E0308]: mismatched types
   --> $DIR/enum-variant-generic-args.rs:28:35
    |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
 LL |         Self::SVariant::<()> { v: () };
-   |                                   ^^ expected type parameter, found ()
+   |                                   ^^ expected type parameter `T`, found ()
    |
    = note: expected type `T`
               found type `()`
@@ -81,8 +93,11 @@ LL |         Self::<()>::SVariant { v: () };
 error[E0308]: mismatched types
   --> $DIR/enum-variant-generic-args.rs:31:35
    |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
 LL |         Self::<()>::SVariant { v: () };
-   |                                   ^^ expected type parameter, found ()
+   |                                   ^^ expected type parameter `T`, found ()
    |
    = note: expected type `T`
               found type `()`
@@ -104,8 +119,11 @@ LL |         Self::<()>::SVariant::<()> { v: () };
 error[E0308]: mismatched types
   --> $DIR/enum-variant-generic-args.rs:34:41
    |
+LL | impl<T> Enum<T> {
+   |      - this type parameter
+...
 LL |         Self::<()>::SVariant::<()> { v: () };
-   |                                         ^^ expected type parameter, found ()
+   |                                         ^^ expected type parameter `T`, found ()
    |
    = note: expected type `T`
               found type `()`

diff --git a/src/test/ui/type/type-parameter-names.rs b/src/test/ui/type/type-parameter-names.rs
@@ -6,7 +6,7 @@ fn foo<Foo, Bar>(x: Foo) -> Bar {
 //~^ ERROR mismatched types
 //~| expected type `Bar`
 //~| found type `Foo`
-//~| expected type parameter, found a different type parameter
+//~| expected type parameter `Bar`, found type parameter `Foo`
 }
 
 fn main() {}
diff --git a/src/test/ui/type/type-parameter-names.stderr b/src/test/ui/type/type-parameter-names.stderr
@@ -2,9 +2,12 @@ error[E0308]: mismatched types
   --> $DIR/type-parameter-names.rs:5:5
    |
 LL | fn foo<Foo, Bar>(x: Foo) -> Bar {
-   |                             --- expected `Bar` because of return type
+   |        ---  ---             --- expected `Bar` because of return type
+   |        |    |
+   |        |    expected type parameter
+   |        found type parameter
 LL |     x
-   |     ^ expected type parameter, found a different type parameter
+   |     ^ expected type parameter `Bar`, found type parameter `Foo`
    |
    = note: expected type `Bar`
               found type `Foo`