[clang] [analyzer] Implement BugReporterVisitor for UseAfterLifetimeEnd to trace lifetime source binding (PR #207052)

[Balázs Benics via cfe-commits]

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@@ -214,6 +248,27 @@ int *no_dangling_sources_ptr(int *a [[clang::lifetimebound]], int *b [[clang::li
 int *one_dangling_source_ptr(int *a [[clang::lifetimebound]]) {
   int x = 1;
   int *x_ptr = &x;
-  return multi_param_test_ptr(a, x_ptr); // expected-warning {{Returning value bound to 'x' that will go out of scope}}
+  return multi_param_test_ptr(a, x_ptr);
+  // expected-warning at -1 {{Returning value bound to 'x' that will go out of scope}}
+  // expected-note at -2 {{Value bound to 'x' here}}
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steakhal wrote:

@benedekaibas  I think you are missing my point. Pointing at the declaration is easy. That's not interesting because most often they only declare a single variable - thus there is no confusion for the user.

However, where could be confusion is this, and read closely:
```
return multi_param_test_ptr(a, x_ptr);
  // expected-warning at -1 {{Returning value bound to 'x' that will go out of scope}} <-- what is 'x'?
  // expected-note at -2 {{Value bound to 'x' here}}  <-- what is 'here'? (does it have a line:col range)
```

What does 'x' refer to in the call expr `multi_param_test_ptr(a, x_ptr)`. The problem is that `x` is not spelled there at all. It's super confusing. While in this case you intentionally correlated the name `x_ptr` which makes sense for the test but you should assume it has some unrelated name. So what is `x`?

One way to help with this is by underlining the part of the call expr that has `x` - but I'll let you speculate of how to improve this diag message because right now it's not going to cut it for the users.

https://github.com/llvm/llvm-project/pull/207052