Print ParamTy span when accessing a field (#52082)

src/librustc_typeck/check/expr.rs

@@ -1390,30 +1390,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  } else if self.method_exists(field, expr_t, expr.hir_id, true) {
  self.ban_take_value_of_method(expr, expr_t, field);
  } else if !expr_t.is_primitive_ty() {
- let mut err = self.no_such_field_err(field.span, field, expr_t);
-
- match expr_t.kind {
- ty::Adt(def, _) if !def.is_enum() => {
- self.suggest_fields_on_recordish(&mut err, def, field);
- }
- ty::Array(_, len) => {
- self.maybe_suggest_array_indexing(&mut err, expr, base, field, len);
- }
- ty::RawPtr(..) => {
- self.suggest_first_deref_field(&mut err, expr, base, field);
- }
- _ => {}
- }
-
- if field.name == kw::Await {
- // We know by construction that `<expr>.await` is either on Rust 2015
- // or results in `ExprKind::Await`. Suggest switching the edition to 2018.
- err.note("to `.await` a `Future`, switch to Rust 2018");
- err.help("set `edition = \"2018\"` in `Cargo.toml`");
- err.note("for more on editions, read https://doc.rust-lang.org/edition-guide");
- }
-
- err.emit();
+ self.ban_nonexisting_field(field, base, expr, expr_t);
  } else {
  type_error_struct!(
  self.tcx().sess,
@@ -1429,6 +1406,42 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  self.tcx().types.err
  }
 
+ fn ban_nonexisting_field(
+ &self,
+ field: ast::Ident,
+ base: &'tcx hir::Expr,
+ expr: &'tcx hir::Expr,
+ expr_t: Ty<'tcx>,
+ ) {
+ let mut err = self.no_such_field_err(field.span, field, expr_t);
+
+ match expr_t.peel_refs().kind {
+ ty::Array(_, len) => {
+ self.maybe_suggest_array_indexing(&mut err, expr, base, field, len);
+ }
+ ty::RawPtr(..) => {
+ self.suggest_first_deref_field(&mut err, expr, base, field);
+ }
+ ty::Adt(def, _) if !def.is_enum() => {
+ self.suggest_fields_on_recordish(&mut err, def, field);
+ }
+ ty::Param(param_ty) => {
+ self.point_at_param_definition(&mut err, param_ty);
+ }
+ _ => {}
+ }
+
+ if field.name == kw::Await {
+ // We know by construction that `<expr>.await` is either on Rust 2015
+ // or results in `ExprKind::Await`. Suggest switching the edition to 2018.
+ err.note("to `.await` a `Future`, switch to Rust 2018");
+ err.help("set `edition = \"2018\"` in `Cargo.toml`");
+ err.note("for more on editions, read https://doc.rust-lang.org/edition-guide");
+ }
+
+ err.emit();
+ }
+
  fn ban_private_field_access(
  &self,
  expr: &hir::Expr,
@@ -1491,6 +1504,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
  err.emit();
  }
 
+ fn point_at_param_definition(&self, err: &mut DiagnosticBuilder<'_>, param: ty::ParamTy) {
+ let generics = self.tcx.generics_of(self.body_id.owner_def_id());
+ let generic_param = generics.type_param(&param, self.tcx);
+ if let ty::GenericParamDefKind::Type{synthetic: Some(..), ..} = generic_param.kind {
+ return;
+ }
+ let param_def_id = generic_param.def_id;
+ let param_hir_id = match self.tcx.hir().as_local_hir_id(param_def_id) {
+ Some(x) => x,
+ None => return,
+ };
+ let param_span = self.tcx.hir().span(param_hir_id);
+ let param_name = self.tcx.hir().ty_param_name(param_hir_id);
+
+ err.span_label(param_span, &format!("type parameter '{}' declared here", param_name));
+ }
+
  fn suggest_fields_on_recordish(
  &self,
  err: &mut DiagnosticBuilder<'_>,

src/test/ui/derived-errors/issue-30580.stderr

@@ -2,7 +2,7 @@ error[E0609]: no field `c` on type `&Foo`
  --> $DIR/issue-30580.rs:12:11
  |
 LL | b.c;
- | ^
+ | ^ help: a field with a similar name exists: `a`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-31011.stderr

@@ -4,6 +4,9 @@ error[E0609]: no field `trace` on type `&T`
 LL | if $ctx.trace {
  | ^^^^^
 ...
+LL | fn wrap<T>(context: &T) -> ()
+ | - type parameter 'T' declared here
+LL | {
 LL | log!(context, "entered wrapper");
  | --------------------------------- in this macro invocation
 

src/test/ui/structs/struct-pat-derived-error.stderr

@@ -2,7 +2,7 @@ error[E0609]: no field `d` on type `&A`
  --> $DIR/struct-pat-derived-error.rs:8:31
  |
 LL | let A { x, y } = self.d;
- | ^
+ | ^ help: a field with a similar name exists: `b`
 
 error[E0026]: struct `A` does not have fields named `x`, `y`
  --> $DIR/struct-pat-derived-error.rs:8:17

src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.rs

@@ -0,0 +1,54 @@
+// Fix issue 52082: Confusing error if accidentially defining a type paramter with the same name as
+// an existing type
+//
+// To this end, make sure that when trying to retrieve a field of a (reference to) type parameter,
+// rustc points to the point where the parameter was defined.
+#[derive(Debug)]
+struct Point
+{
+ x: i32,
+ y: i32
+}
+
+impl Point
+{
+ fn add(a: &Point, b: &Point) -> Point
+ {
+ Point {x: a.x + b.x, y: a.y + b.y}
+ }
+}
+
+trait Eq
+{
+ fn equals_ref<T>(a: &T, b: &T) -> bool;
+ fn equals_val<T>(a: T, b: T) -> bool;
+}
+
+impl Eq for Point
+{
+ fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+ {
+ a.x == b.x && a.y == b.y //~ ERROR no field `x` on type `&Point` [E0609]
+ //~|ERROR no field `x` on type `&Point` [E0609]
+ //~|ERROR no field `y` on type `&Point` [E0609]
+ //~|ERROR no field `y` on type `&Point` [E0609]
+ }
+
+ fn equals_val<Point>(a: Point, b: Point) -> bool
+ {
+ a.x == b.x && a.y == b.y //~ ERROR no field `x` on type `Point` [E0609]
+ //~|ERROR no field `x` on type `Point` [E0609]
+ //~|ERROR no field `y` on type `Point` [E0609]
+ //~|ERROR no field `y` on type `Point` [E0609]
+ }
+}
+
+fn main()
+{
+ let p1 = Point {x: 0, y: 10};
+ let p2 = Point {x: 20, y: 42};
+ println!("{:?}", Point::add(&p1, &p2));
+ println!("p1: {:?}, p2: {:?}", p1, p2);
+ println!("&p1 == &p2: {:?}", Point::equals_ref(&p1, &p2));
+ println!("p1 == p2: {:?}", Point::equals_val(p1, p2));
+}

src/test/ui/typeck/issue-52082-type-param-shadows-existing-type.stderr

@@ -0,0 +1,75 @@
+error[E0609]: no field `x` on type `&Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:11
+ |
+LL | fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `x` on type `&Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:18
+ |
+LL | fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `y` on type `&Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:25
+ |
+LL | fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `y` on type `&Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:31:32
+ |
+LL | fn equals_ref<Point>(a: &Point, b: &Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `x` on type `Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:11
+ |
+LL | fn equals_val<Point>(a: Point, b: Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `x` on type `Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:18
+ |
+LL | fn equals_val<Point>(a: Point, b: Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `y` on type `Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:25
+ |
+LL | fn equals_val<Point>(a: Point, b: Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error[E0609]: no field `y` on type `Point`
+ --> $DIR/issue-52082-type-param-shadows-existing-type.rs:39:32
+ |
+LL | fn equals_val<Point>(a: Point, b: Point) -> bool
+ | ----- type parameter 'Point' declared here
+LL | {
+LL | a.x == b.x && a.y == b.y
+ | ^
+
+error: aborting due to 8 previous errors
+
+For more information about this error, try `rustc --explain E0609`.