[PATCH] D136751: [clang][Interp] This pointers are writable in constructors

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: clang/lib/AST/Interp/Interp.cpp:221-225
+  if (const Function *Func = S.Current->getFunction();
+      Func && (Func->isConstructor() || Func->isDestructor())) {
+    if (Ptr.block() == S.Current->getThis().block())
+      return true;
   }
----------------
Combining predicates; NFC


================
Comment at: clang/test/AST/Interp/cxx20.cpp:221-230
+  class FooDtor {
+    int a;
+  public:
+    constexpr FooDtor() {
+      this->a = 10;
+    }
+    constexpr ~FooDtor() {
----------------
I'd feel more comfortable if we had some way to validate that the write to `a` in both of these cases actually caused the correct value to appear in `a`. We're just validating that this compiles and doesn't crash, but we're not validating that the actual behavior occurs. How about adding tests like:
```
template <bool Good>
struct ctor_test {
  int a = 0;

  constexpr ctor_test() {
    if (Good)
      a = 10;
    int local = 100 / a;
  }
};

template <bool Good>
struct dtor_test {
  int a = 0;

  constexpr dtor_test() = default;
  constexpr ~dtor_test() {
    if (Good)
      a = 10;
    int local = 100 / a;
  }
};

constexpr ctor_test<true> good_ctor;
constexpr dtor_test<true> good_dtor;

constexpr ctor_test<false> bad_ctor;
constexpr dtor_test<false> bad_dtor;
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D136751/new/

https://reviews.llvm.org/D136751