`best_blame_constraint`: avoid blaming assignments without user-provided types

2 files changed, 21 insertions, 24 deletions

diff --git a/tests/ui/fn/fn_def_coercion.rs b/tests/ui/fn/fn_def_coercion.rs
index 31c8fa41de1..313be6f28cd 100644
--- a/tests/ui/fn/fn_def_coercion.rs
+++ b/tests/ui/fn/fn_def_coercion.rs
@@ -46,12 +46,12 @@ fn j<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
 
 fn k<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
     let x = match true {
-        true => foo::<&'c ()>, //~ ERROR lifetime may not live long enough
+        true => foo::<&'c ()>,
         false => foo::<&'a ()>, //~ ERROR lifetime may not live long enough
     };
 
     x(a);
-    x(b);
+    x(b); //~ ERROR lifetime may not live long enough
     x(c);
 }
 
diff --git a/tests/ui/fn/fn_def_coercion.stderr b/tests/ui/fn/fn_def_coercion.stderr
index c2776887b79..ec4a1bde7fd 100644
--- a/tests/ui/fn/fn_def_coercion.stderr
+++ b/tests/ui/fn/fn_def_coercion.stderr
@@ -6,9 +6,9 @@ LL | fn f<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      |
    |      lifetime `'a` defined here
 LL |     let mut x = foo::<&'a ()>;
-   |                 ^^^^^^^^^^^^^ assignment requires that `'b` must outlive `'a`
+   |                 ^^^^^^^^^^^^^ assignment 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 function pointer to `foo`
    = note: the function `foo` is invariant over the parameter `T`
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -22,9 +22,9 @@ LL | fn f<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      lifetime `'a` defined here
 LL |     let mut x = foo::<&'a ()>;
 LL |     x = foo::<&'b ()>;
-   |     ^^^^^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'b`
+   |     ^^^^^^^^^^^^^^^^^ assignment 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 function pointer to `foo`
    = note: the function `foo` is invariant over the parameter `T`
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -53,9 +53,9 @@ LL | fn i<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      lifetime `'a` defined here
 LL |     let mut x = foo::<&'c ()>;
 LL |     x = foo::<&'b ()>;
-   |     ^^^^^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'b`
+   |     ^^^^^^^^^^^^^^^^^ assignment 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 function pointer to `foo`
    = note: the function `foo` is invariant over the parameter `T`
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -69,9 +69,9 @@ LL | fn i<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      lifetime `'a` defined here
 ...
 LL |     x = foo::<&'a ()>;
-   |     ^^^^^^^^^^^^^^^^^ assignment requires that `'b` must outlive `'a`
+   |     ^^^^^^^^^^^^^^^^^ assignment 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 function pointer to `foo`
    = note: the function `foo` is invariant over the parameter `T`
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -89,9 +89,9 @@ LL | fn j<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      lifetime `'a` defined here
 LL |     let x = match true {
 LL |         true => foo::<&'b ()>,
-   |                 ^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'b`
+   |                 ^^^^^^^^^^^^^ assignment 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 function pointer to `foo`
    = note: the function `foo` is invariant over the parameter `T`
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -105,9 +105,9 @@ LL | fn j<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      lifetime `'a` defined here
 ...
 LL |         false => foo::<&'a ()>,
-   |                  ^^^^^^^^^^^^^ assignment requires that `'b` must outlive `'a`
+   |                  ^^^^^^^^^^^^^ assignment 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 function pointer to `foo`
    = note: the function `foo` is invariant over the parameter `T`
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
@@ -117,15 +117,15 @@ help: `'a` and `'b` must be the same: replace one with the other
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: lifetime may not live long enough
-  --> $DIR/fn_def_coercion.rs:49:17
+  --> $DIR/fn_def_coercion.rs:50:18
    |
 LL | fn k<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      --      -- lifetime `'c` defined here
    |      |
    |      lifetime `'a` defined here
-LL |     let x = match true {
-LL |         true => foo::<&'c ()>,
-   |                 ^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'c`
+...
+LL |         false => foo::<&'a ()>,
+   |                  ^^^^^^^^^^^^^ assignment requires that `'a` must outlive `'c`
    |
    = help: consider adding the following bound: `'a: 'c`
    = note: requirement occurs because of a function pointer to `foo`
@@ -133,20 +133,17 @@ LL |         true => foo::<&'c ()>,
    = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
 
 error: lifetime may not live long enough
-  --> $DIR/fn_def_coercion.rs:50:18
+  --> $DIR/fn_def_coercion.rs:54:5
    |
 LL | fn k<'a, 'b, 'c: 'a + 'b>(a: &'a (), b: &'b (), c: &'c ()) {
    |      --  -- lifetime `'b` defined here
    |      |
    |      lifetime `'a` defined here
 ...
-LL |         false => foo::<&'a ()>,
-   |                  ^^^^^^^^^^^^^ assignment requires that `'b` must outlive `'a`
+LL |     x(b);
+   |     ^^^^ argument requires that `'b` must outlive `'a`
    |
    = help: consider adding the following bound: `'b: 'a`
-   = note: requirement occurs because of a function pointer to `foo`
-   = note: the function `foo` is invariant over the parameter `T`
-   = help: see <https://doc.rust-lang.org/nomicon/subtyping.html> for more information about variance
 
 help: the following changes may resolve your lifetime errors
    |