Rollup merge of #134181 - estebank:trim-render, r=oli-obk

Tweak multispan rendering to reduce output length

Consider comments and bare delimiters the same as an "empty line" for purposes of hiding rendered code output of long multispans. This results in more aggressive shortening of rendered output without losing too much context, specially in `*.stderr` tests that have "hidden" comments. We do that check not only on the first 4 lines of the multispan, but now also on the previous to last line as well.

Author: matthiaskrgr

tests/fail-dep/concurrency/windows_join_main.stderr

@@ -24,8 +24,7 @@ note: inside `main`
 LL | /     thread::spawn(|| {
 LL | |         unsafe {
 LL | |             assert_eq!(WaitForSingleObject(MAIN_THREAD, INFINITE), WAIT_OBJECT_0);
-LL | |         }
-LL | |     })
+...  |
 LL | |     .join()
    | |___________^
 

tests/fail/function_calls/arg_inplace_mutate.stack.stderr

@@ -14,7 +14,6 @@ LL | |         let _unit: ();
 LL | |         {
 LL | |             let non_copy = S(42);
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: <TAG> is this argument

tests/fail/function_calls/arg_inplace_mutate.tree.stderr

@@ -16,7 +16,6 @@ LL | |         let _unit: ();
 LL | |         {
 LL | |             let non_copy = S(42);
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: the protected tag <TAG> was created here, in the initial state Reserved

tests/fail/function_calls/arg_inplace_observe_during.stack.stderr

@@ -14,7 +14,6 @@ LL | |         let _unit: ();
 LL | |         {
 LL | |             let non_copy = S(42);
 ...  |
-LL | |
 LL | |     }
    | |_____^
 help: <TAG> is this argument

tests/fail/function_calls/arg_inplace_observe_during.tree.stderr

@@ -16,7 +16,6 @@ LL | |         let _unit: ();
 LL | |         {
 LL | |             let non_copy = S(42);
 ...  |
-LL | |
 LL | |     }
    | |_____^
 help: the protected tag <TAG> was created here, in the initial state Reserved

tests/fail/function_calls/return_pointer_aliasing_read.stack.stderr

@@ -14,7 +14,6 @@ LL | |         {
 LL | |             let x = 0;
 LL | |             let ptr = &raw mut x;
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: <TAG> is this argument

tests/fail/function_calls/return_pointer_aliasing_read.tree.stderr

@@ -16,7 +16,6 @@ LL | |         {
 LL | |             let x = 0;
 LL | |             let ptr = &raw mut x;
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: the protected tag <TAG> was created here, in the initial state Reserved

tests/fail/function_calls/return_pointer_aliasing_write.stack.stderr

@@ -14,7 +14,6 @@ LL | |         {
 LL | |             let _x = 0;
 LL | |             let ptr = &raw mut _x;
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: <TAG> is this argument

tests/fail/function_calls/return_pointer_aliasing_write.tree.stderr

@@ -16,7 +16,6 @@ LL | |         {
 LL | |             let _x = 0;
 LL | |             let ptr = &raw mut _x;
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: the protected tag <TAG> was created here, in the initial state Reserved

tests/fail/function_calls/return_pointer_aliasing_write_tail_call.stack.stderr

@@ -14,7 +14,6 @@ LL | |         {
 LL | |             let _x = 0;
 LL | |             let ptr = &raw mut _x;
 ...  |
-LL | |         }
 LL | |     }
    | |_____^
 help: <TAG> is this argument