[Clang] Correctly handle allocations in the condition of a `if constexpr` (#146890)

Deal with the following scenario

```cpp
struct S {
    char* c = new char;
    constexpr ~S() {
        delete c;
    }
};
if constexpr((S{}, true)){};
```

There were two issues
- We need to produce a full expression _before_ evaluating the condition
(otherwise, automatic variables are never destroyed)
- We need to preserve the evaluation context of the condition while
doing the semantics analysis for it (lest it is evaluated in a
non-constant-evaluated context)

Fixes #120197
Fixes #134820

0 files changed, 0 insertions, 0 deletions