[clang] [clang] improve print / dump of anonymous declarations (PR #124605)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

The test case provided shows a bug in the original implementation of the analyzer anyway.

Here is the clang output for the slightly reduced repro:
```C++
struct A {
  static A a;
  char b;
  friend bool operator==(A, A) = default;
};
bool _ = A() == A::a;
```

Original clang outputs:
```
bool operator==(A, A) noexcept = default
 [B2 (ENTRY)]
   Succs (1): B1

 [B1]
   1: 
   2: [B1.1].b
   3: [B1.2] (ImplicitCastExpr, LValueToRValue, char)
   4: [B1.3] (ImplicitCastExpr, IntegralCast, int)
   5: 
   6: [B1.5].b
   7: [B1.6] (ImplicitCastExpr, LValueToRValue, char)
   8: [B1.7] (ImplicitCastExpr, IntegralCast, int)
   9: [B1.4] == [B1.8]
  10: return [B1.9];
   Preds (1): B2
   Succs (1): B0

 [B0 (EXIT)]
   Preds (1): B1
```

Notice how steps 1 and 5 are empty.

After my next changes to this patch, here is how it will print:
```
bool operator==(A, A) noexcept = default
 [B2 (ENTRY)]
   Succs (1): B1

 [B1]
   1: function-parameter-0-0
   2: [B1.1].b
   3: [B1.2] (ImplicitCastExpr, LValueToRValue, char)
   4: [B1.3] (ImplicitCastExpr, IntegralCast, int)
   5: function-parameter-0-1
   6: [B1.5].b
   7: [B1.6] (ImplicitCastExpr, LValueToRValue, char)
   8: [B1.7] (ImplicitCastExpr, IntegralCast, int)
   9: [B1.4] == [B1.8]
  10: return [B1.9];
   Preds (1): B2
   Succs (1): B0

 [B0 (EXIT)]
   Preds (1): B1
```

At least it will print the parameter depth and indexes, but this still should be fixed in the analyzer somehow.

I still think leaving the assert was the right call, it led us to finding bugs as expected :)

https://github.com/llvm/llvm-project/pull/124605