make outlives constraints from pointer comparisons less boring

Author: dianne

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -2181,7 +2181,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             ty_left,
                             common_ty,
                             location.to_locations(),
-                            ConstraintCategory::Boring,
+                            ConstraintCategory::CallArgument(None),
                         )
                         .unwrap_or_else(|err| {
                             bug!("Could not equate type variable with {:?}: {:?}", ty_left, err)
@@ -2190,7 +2190,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             ty_right,
                             common_ty,
                             location.to_locations(),
-                            ConstraintCategory::Boring,
+                            ConstraintCategory::CallArgument(None),
                         ) {
                             span_mirbug!(
                                 self,

tests/ui/nll/type-check-pointer-comparisons.stderr

@@ -6,24 +6,24 @@ LL | fn compare_const<'a, 'b>(x: *const &mut &'a i32, y: *const &mut &'b i32) {
    |                  |
    |                  lifetime `'a` defined here
 LL |     x == y;
-   |     ^ requires that `'b` must outlive `'a`
+   |     ^^^^^^ argument requires that `'a` must outlive `'b`
    |
-   = help: consider adding the following bound: `'b: 'a`
+   = help: consider adding the following bound: `'a: 'b`
    = note: requirement occurs because of a mutable reference to `&i32`
    = note: mutable references are invariant over their type parameter
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
 
 error: lifetime may not live long enough
-  --> $DIR/type-check-pointer-comparisons.rs:4:10
+  --> $DIR/type-check-pointer-comparisons.rs:4:5
    |
 LL | fn compare_const<'a, 'b>(x: *const &mut &'a i32, y: *const &mut &'b i32) {
    |                  --  -- lifetime `'b` defined here
    |                  |
    |                  lifetime `'a` defined here
 LL |     x == y;
-   |          ^ requires that `'a` must outlive `'b`
+   |     ^^^^^^ argument requires that `'b` must outlive `'a`
    |
-   = help: consider adding the following bound: `'a: 'b`
+   = help: consider adding the following bound: `'b: 'a`
    = note: requirement occurs because of a mutable reference to `&i32`
    = note: mutable references are invariant over their type parameter
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -38,24 +38,24 @@ LL | fn compare_mut<'a, 'b>(x: *mut &'a i32, y: *mut &'b i32) {
    |                |
    |                lifetime `'a` defined here
 LL |     x == y;
-   |     ^ requires that `'b` must outlive `'a`
+   |     ^^^^^^ argument requires that `'a` must outlive `'b`
    |
-   = help: consider adding the following bound: `'b: 'a`
+   = help: consider adding the following bound: `'a: 'b`
    = note: requirement occurs because of a mutable pointer to `&i32`
    = note: mutable pointers are invariant over their type parameter
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
 
 error: lifetime may not live long enough
-  --> $DIR/type-check-pointer-comparisons.rs:10:10
+  --> $DIR/type-check-pointer-comparisons.rs:10:5
    |
 LL | fn compare_mut<'a, 'b>(x: *mut &'a i32, y: *mut &'b i32) {
    |                --  -- lifetime `'b` defined here
    |                |
    |                lifetime `'a` defined here
 LL |     x == y;
-   |          ^ requires that `'a` must outlive `'b`
+   |     ^^^^^^ argument requires that `'b` must outlive `'a`
    |
-   = help: consider adding the following bound: `'a: 'b`
+   = help: consider adding the following bound: `'b: 'a`
    = note: requirement occurs because of a mutable pointer to `&i32`
    = note: mutable pointers are invariant over their type parameter
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -72,24 +72,24 @@ LL | fn compare_fn_ptr<'a, 'b, 'c>(f: fn(&'c mut &'a i32), g: fn(&'c mut &'b i32
    |                   |
    |                   lifetime `'a` defined here
 LL |     f == g;
-   |     ^ requires that `'b` must outlive `'a`
+   |     ^^^^^^ argument requires that `'a` must outlive `'b`
    |
-   = help: consider adding the following bound: `'b: 'a`
+   = help: consider adding the following bound: `'a: 'b`
    = note: requirement occurs because of a mutable reference to `&i32`
    = note: mutable references are invariant over their type parameter
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
 
 error: lifetime may not live long enough
-  --> $DIR/type-check-pointer-comparisons.rs:16:10
+  --> $DIR/type-check-pointer-comparisons.rs:16:5
    |
 LL | fn compare_fn_ptr<'a, 'b, 'c>(f: fn(&'c mut &'a i32), g: fn(&'c mut &'b i32)) {
    |                   --  -- lifetime `'b` defined here
    |                   |
    |                   lifetime `'a` defined here
 LL |     f == g;
-   |          ^ requires that `'a` must outlive `'b`
+   |     ^^^^^^ argument requires that `'b` must outlive `'a`
    |
-   = help: consider adding the following bound: `'a: 'b`
+   = help: consider adding the following bound: `'b: 'a`
    = note: requirement occurs because of a mutable reference to `&i32`
    = note: mutable references are invariant over their type parameter
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance