Always point at index span on index obligation failure

Use more targetted span for index obligation failures by rewriting the
obligation cause span.

CC #66023

2 files changed, 20 insertions, 0 deletions

diff --git a/tests/ui/indexing/point-at-index-for-obligation-failure.rs b/tests/ui/indexing/point-at-index-for-obligation-failure.rs
new file mode 100644
index 00000000000..e9c429b53ce
--- /dev/null
+++ b/tests/ui/indexing/point-at-index-for-obligation-failure.rs
@@ -0,0 +1,7 @@
+fn main() {
+    let a = std::collections::HashMap::<String,String>::new();
+    let s = "hello";
+    let _b = a[
+        &s //~ ERROR E0277
+    ];
+}
diff --git a/tests/ui/indexing/point-at-index-for-obligation-failure.stderr b/tests/ui/indexing/point-at-index-for-obligation-failure.stderr
new file mode 100644
index 00000000000..3e2fbc2ab6f
--- /dev/null
+++ b/tests/ui/indexing/point-at-index-for-obligation-failure.stderr
@@ -0,0 +1,13 @@
+error[E0277]: the trait bound `String: Borrow<&str>` is not satisfied
+  --> $DIR/point-at-index-for-obligation-failure.rs:5:9
+   |
+LL |         &s
+   |         ^^ the trait `Borrow<&str>` is not implemented for `String`
+   |
+   = help: the trait `Borrow<str>` is implemented for `String`
+   = help: for that trait implementation, expected `str`, found `&str`
+   = note: required for `HashMap<String, String>` to implement `Index<&&str>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.