rustc_mir: Re-use report_selection_error.

davidtwco · davidtwco · commit 813c994a754b · 2019-07-07T19:51:31.000+01:00
This commit replaces the new error that was being emitted in NLL type
check with a call to `report_selection_error` so that the same trait
error as before this PR is emitted.
diff --git a/src/librustc/traits/error_reporting.rs b/src/librustc/traits/error_reporting.rs
@@ -1564,6 +1564,10 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 err.note(&format!("required for the cast to the object type `{}`",
                                   self.ty_to_string(object_ty)));
             }
+            ObligationCauseCode::RepeatVec => {
+                err.note("the `Copy` trait is required because the \
+                          repeated element will be copied");
+            }
             ObligationCauseCode::VariableType(_) => {
                 err.note("all local variables must have a statically known size");
                 if !self.tcx.features().unsized_locals {
diff --git a/src/librustc/traits/mod.rs b/src/librustc/traits/mod.rs
@@ -195,6 +195,8 @@ pub enum ObligationCauseCode<'tcx> {
     SizedReturnType,
     /// Yield type must be Sized
     SizedYieldType,
+    /// [T,..n] --> T must be Copy
+    RepeatVec,
 
     /// Types of fields (other than the last, except for packed structs) in a struct must be sized.
     FieldSized { adt_kind: AdtKind, last: bool },
diff --git a/src/librustc/traits/structural_impls.rs b/src/librustc/traits/structural_impls.rs
@@ -488,6 +488,7 @@ impl<'a, 'tcx> Lift<'tcx> for traits::ObligationCauseCode<'a> {
             super::SizedArgumentType => Some(super::SizedArgumentType),
             super::SizedReturnType => Some(super::SizedReturnType),
             super::SizedYieldType => Some(super::SizedYieldType),
+            super::RepeatVec => Some(super::RepeatVec),
             super::FieldSized { adt_kind, last } => Some(super::FieldSized { adt_kind, last }),
             super::ConstSized => Some(super::ConstSized),
             super::SharedStatic => Some(super::SharedStatic),
diff --git a/src/librustc_mir/borrow_check/nll/type_check/mod.rs b/src/librustc_mir/borrow_check/nll/type_check/mod.rs
@@ -35,7 +35,7 @@ use rustc::mir::*;
 use rustc::traits::query::type_op;
 use rustc::traits::query::type_op::custom::CustomTypeOp;
 use rustc::traits::query::{Fallible, NoSolution};
-use rustc::traits::{ObligationCause, PredicateObligations};
+use rustc::traits::{self, ObligationCause, PredicateObligations};
 use rustc::ty::adjustment::{PointerCast};
 use rustc::ty::fold::TypeFoldable;
 use rustc::ty::subst::{Subst, SubstsRef, UnpackedKind, UserSubsts};
@@ -1968,25 +1968,25 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                     // a required check to make sure that repeated elements implement `Copy`.
                     let span = body.source_info(location).span;
                     let ty = operand.ty(body, tcx);
-                    let is_copy = self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span);
-                    if !is_copy {
-                        let copy_path = self.tcx().def_path_str(
-                            self.tcx().lang_items().copy_trait().unwrap());
-                        self.tcx().sess
-                            .struct_span_err(
-                                span,
-                                &format!("repeated expression does not implement `{}`", copy_path),
-                            )
-                            .span_label(span, &format!(
-                                "the trait `{}` is not implemented for `{}`",
-                                copy_path, ty,
-                            ))
-                            .note(&format!(
-                                "the `{}` trait is required because the repeated element will be \
-                                 copied",
-                                 copy_path,
-                            ))
-                            .emit();
+                    if !self.infcx.type_is_copy_modulo_regions(self.param_env, ty, span) {
+                        self.infcx.report_selection_error(
+                            &traits::Obligation::new(
+                                ObligationCause::new(
+                                    span,
+                                    self.tcx().hir().def_index_to_hir_id(self.mir_def_id.index),
+                                    traits::ObligationCauseCode::RepeatVec,
+                                ),
+                                self.param_env,
+                                ty::Predicate::Trait(ty::Binder::bind(ty::TraitPredicate {
+                                    trait_ref: ty::TraitRef::new(
+                                        self.tcx().lang_items().copy_trait().unwrap(),
+                                        tcx.mk_substs_trait(ty, &[]),
+                                    ),
+                                })),
+                            ),
+                            &traits::SelectionError::Unimplemented,
+                            false,
+                        );
                     }
                 }
             },
diff --git a/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/migrate-borrowck.rs b/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/migrate-borrowck.rs
@@ -86,7 +86,7 @@ mod non_constants {
     fn no_impl_copy_empty_value_multiple_elements() {
         let x = None;
         let arr: [Option<Bar>; 2] = [x; 2];
-        //~^ ERROR repeated expression does not implement `std::marker::Copy`
+        //~^ ERROR the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied [E0277]
     }
 
     fn no_impl_copy_value_no_elements() {
@@ -102,7 +102,7 @@ mod non_constants {
     fn no_impl_copy_value_multiple_elements() {
         let x = Some(Bar);
         let arr: [Option<Bar>; 2] = [x; 2];
-        //~^ ERROR repeated expression does not implement `std::marker::Copy`
+        //~^ ERROR the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied [E0277]
     }
 
     fn impl_copy_empty_value_no_elements() {
diff --git a/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/migrate-borrowck.stderr b/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/migrate-borrowck.stderr
@@ -1,18 +1,23 @@
-error: repeated expression does not implement `std::marker::Copy`
+error[E0277]: the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied
   --> $DIR/migrate-borrowck.rs:88:37
    |
 LL |         let arr: [Option<Bar>; 2] = [x; 2];
    |                                     ^^^^^^ the trait `std::marker::Copy` is not implemented for `std::option::Option<Bar>`
    |
-   = note: the `std::marker::Copy` trait is required because the repeated element will be copied
+   = help: the following implementations were found:
+             <std::option::Option<T> as std::marker::Copy>
+   = note: the `Copy` trait is required because the repeated element will be copied
 
-error: repeated expression does not implement `std::marker::Copy`
+error[E0277]: the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied
   --> $DIR/migrate-borrowck.rs:104:37
    |
 LL |         let arr: [Option<Bar>; 2] = [x; 2];
    |                                     ^^^^^^ the trait `std::marker::Copy` is not implemented for `std::option::Option<Bar>`
    |
-   = note: the `std::marker::Copy` trait is required because the repeated element will be copied
+   = help: the following implementations were found:
+             <std::option::Option<T> as std::marker::Copy>
+   = note: the `Copy` trait is required because the repeated element will be copied
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/nll-borrowck.rs b/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/nll-borrowck.rs
@@ -85,7 +85,7 @@ mod non_constants {
     fn no_impl_copy_empty_value_multiple_elements() {
         let x = None;
         let arr: [Option<Bar>; 2] = [x; 2];
-        //~^ ERROR repeated expression does not implement `std::marker::Copy`
+        //~^ ERROR the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied [E0277]
     }
 
     fn no_impl_copy_value_no_elements() {
@@ -101,7 +101,7 @@ mod non_constants {
     fn no_impl_copy_value_multiple_elements() {
         let x = Some(Bar);
         let arr: [Option<Bar>; 2] = [x; 2];
-        //~^ ERROR repeated expression does not implement `std::marker::Copy`
+        //~^ ERROR the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied [E0277]
     }
 
     fn impl_copy_empty_value_no_elements() {
diff --git a/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/nll-borrowck.stderr b/src/test/ui/consts/rfc-2203-const-array-repeat-exprs/nll-borrowck.stderr
@@ -1,18 +1,23 @@
-error: repeated expression does not implement `std::marker::Copy`
+error[E0277]: the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied
   --> $DIR/nll-borrowck.rs:87:37
    |
 LL |         let arr: [Option<Bar>; 2] = [x; 2];
    |                                     ^^^^^^ the trait `std::marker::Copy` is not implemented for `std::option::Option<Bar>`
    |
-   = note: the `std::marker::Copy` trait is required because the repeated element will be copied
+   = help: the following implementations were found:
+             <std::option::Option<T> as std::marker::Copy>
+   = note: the `Copy` trait is required because the repeated element will be copied
 
-error: repeated expression does not implement `std::marker::Copy`
+error[E0277]: the trait bound `std::option::Option<Bar>: std::marker::Copy` is not satisfied
   --> $DIR/nll-borrowck.rs:103:37
    |
 LL |         let arr: [Option<Bar>; 2] = [x; 2];
    |                                     ^^^^^^ the trait `std::marker::Copy` is not implemented for `std::option::Option<Bar>`
    |
-   = note: the `std::marker::Copy` trait is required because the repeated element will be copied
+   = help: the following implementations were found:
+             <std::option::Option<T> as std::marker::Copy>
+   = note: the `Copy` trait is required because the repeated element will be copied
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/repeat-to-run-dtor-twice.rs b/src/test/ui/repeat-to-run-dtor-twice.rs
@@ -15,5 +15,5 @@ impl Drop for Foo {
 fn main() {
     let a = Foo { x: 3 };
     let _ = [ a; 5 ];
-    //~^ ERROR repeated expression does not implement `std::marker::Copy`
+    //~^ ERROR the trait bound `Foo: std::marker::Copy` is not satisfied [E0277]
 }
diff --git a/src/test/ui/repeat-to-run-dtor-twice.stderr b/src/test/ui/repeat-to-run-dtor-twice.stderr
@@ -1,10 +1,11 @@
-error: repeated expression does not implement `std::marker::Copy`
+error[E0277]: the trait bound `Foo: std::marker::Copy` is not satisfied
   --> $DIR/repeat-to-run-dtor-twice.rs:17:13
    |
 LL |     let _ = [ a; 5 ];
    |             ^^^^^^^^ the trait `std::marker::Copy` is not implemented for `Foo`
    |
-   = note: the `std::marker::Copy` trait is required because the repeated element will be copied
+   = note: the `Copy` trait is required because the repeated element will be copied
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0277`.

Original file line number	Diff line number	Diff line change
`@@ -15,5 +15,5 @@ impl Drop for Foo {`
`15`	`15`	`fn main() {`
`16`	`16`	`let a = Foo { x: 3 };`
`17`	`17`	`let _ = [ a; 5 ];`
`18`		- //~^ ERROR repeated expression does not implement `std::marker::Copy`
	`18`	+ //~^ ERROR the trait bound `Foo: std::marker::Copy` is not satisfied [E0277]
`19`	`19`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,10 +1,11 @@`
`1`		-error: repeated expression does not implement `std::marker::Copy`
	`1`	+error[E0277]: the trait bound `Foo: std::marker::Copy` is not satisfied
`2`	`2`	`--> $DIR/repeat-to-run-dtor-twice.rs:17:13`
`3`	`3`	`\|`
`4`	`4`	`LL \| let _ = [ a; 5 ];`
`5`	`5`	\| ^^^^^^^^ the trait `std::marker::Copy` is not implemented for `Foo`
`6`	`6`	`\|`
`7`		- = note: the `std::marker::Copy` trait is required because the repeated element will be copied
	`7`	+ = note: the `Copy` trait is required because the repeated element will be copied
`8`	`8`
`9`	`9`	`error: aborting due to previous error`
`10`	`10`
	`11`	+For more information about this error, try `rustc --explain E0277`.