[clang] [clang][bytecode] Assert on virtual func call from array elem (PR #158502)

[marius doerner via cfe-commits]

Marius =?utf-8?q?Dörner?= <marius.doerner1 at icloud.com>,
Marius =?utf-8?q?Dörner?= <marius.doerner1 at icloud.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/158502 at github.com>


================
@@ -1636,6 +1639,33 @@ bool Call(InterpState &S, CodePtr OpPC, const Function *Func,
   return true;
 }
 
+static bool GetDynamicDecl(InterpState &S, CodePtr OpPC, Pointer TypePtr,
+                           const CXXRecordDecl *&DynamicDecl) {
+  while (TypePtr.isBaseClass())
+    TypePtr = TypePtr.getBase();
+
+  QualType DynamicType = TypePtr.getType();
+  if (DynamicType->isPointerType() || DynamicType->isReferenceType()) {
+    DynamicDecl = DynamicType->getPointeeCXXRecordDecl();
+  } else if (DynamicType->isArrayType()) {
+    const Type *ElemType = DynamicType->getPointeeOrArrayElementType();
+    assert(ElemType);
+    DynamicDecl = ElemType->getAsCXXRecordDecl();
+  } else {
+    DynamicDecl = DynamicType->getAsCXXRecordDecl();
+  }
+
+  if (!CheckConstant(S, OpPC, TypePtr, true)) {
----------------
mariusdr wrote:

`DynamicType.isConstant()` would reject valid code like

```
  struct A {
    constexpr virtual void foo(int &a) {
      a = 1;
    }
  };

  constexpr int m() {
    A b;
    int a;
    b.foo(a);
    return a;
  }
  static_assert(m() == 1, "");
```

here `TypePtr.isStatic()` is false so `CheckConstant()` returns early but I'm not sure if it is sufficient to only check those two things.

https://github.com/llvm/llvm-project/pull/158502