Improve overall quality of compile_error! errors

Also updates UI tests.

test_suite/tests/ui/borrow/bad_lifetimes.stderr

@@ -1,8 +1,8 @@
 error: failed to parse borrowed lifetimes: "zzz"
- --> $DIR/bad_lifetimes.rs:4:10
+ --> $DIR/bad_lifetimes.rs:6:22
   |
-4 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+6 |     #[serde(borrow = "zzz")]
+  |                      ^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/duplicate_lifetime.stderr

@@ -1,8 +1,8 @@
 error: duplicate borrowed lifetime `'a`
- --> $DIR/duplicate_lifetime.rs:4:10
+ --> $DIR/duplicate_lifetime.rs:6:22
   |
-4 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+6 |     #[serde(borrow = "'a + 'a")]
+  |                      ^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/duplicate_variant.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `borrow`
- --> $DIR/duplicate_variant.rs:7:10
+ --> $DIR/duplicate_variant.rs:9:13
   |
-7 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+9 |     #[serde(borrow)]
+  |             ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/empty_lifetimes.stderr

@@ -1,8 +1,8 @@
 error: at least one lifetime must be borrowed
- --> $DIR/empty_lifetimes.rs:4:10
+ --> $DIR/empty_lifetimes.rs:6:22
   |
-4 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+6 |     #[serde(borrow = "")]
+  |                      ^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/no_lifetimes.stderr

@@ -1,8 +1,9 @@
 error: field `s` has no lifetimes to borrow
- --> $DIR/no_lifetimes.rs:4:10
+ --> $DIR/no_lifetimes.rs:6:5
   |
-4 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+6 | /     #[serde(borrow)]
+7 | |     s: String,
+  | |_____________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/struct_variant.stderr

@@ -1,8 +1,9 @@
 error: #[serde(borrow)] may only be used on newtype variants
- --> $DIR/struct_variant.rs:7:10
-  |
-7 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+  --> $DIR/struct_variant.rs:9:5
+   |
+9  | /     #[serde(borrow)]
+10 | |     S { s: Str<'a> },
+   | |____________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/wrong_lifetime.stderr

@@ -1,8 +1,9 @@
 error: field `s` does not have lifetime 'b
- --> $DIR/wrong_lifetime.rs:4:10
+ --> $DIR/wrong_lifetime.rs:6:5
   |
-4 | #[derive(Deserialize)]
-  |          ^^^^^^^^^^^
+6 | /     #[serde(borrow = "'b")]
+7 | |     s: &'a str,
+  | |______________^
 
 error: aborting due to previous error