[clang][bytecode] Allow forming pointers to fields of extern globals (#137211)
This should be fine as long as we're not reading from it.
Note that this regresses
CXX/special/class.init/class.inhctor.init/p1.cpp, which used to work
fine with the bytecode interpreter.
That's because this code now fails:
```c++
struct Param;
struct A {
constexpr A(Param);
int a;
};
struct B : A { B(); using A::A; int b = 2; };
struct Wrap1 : B { constexpr Wrap1(); };
struct Wrap2 : Wrap1 {};
extern const Wrap2 b;
struct Param {
constexpr Param(int c) : n(4 * b.a + b.b + c) {}
int n;
};
```
and reports that the Param() constructor is never a valid constant
expression. But that's true and the current interpeter should report
that as well. It also fails when calling at compile time.diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
index 6f277a7..23fd894 100644
--- a/clang/lib/AST/ByteCode/Interp.cpp
+++ b/clang/lib/AST/ByteCode/Interp.cpp
@@ -1323,8 +1323,6 @@
!CheckNull(S, OpPC, Ptr, CSK_Field))
return false;
- if (!CheckExtern(S, OpPC, Ptr))
- return false;
if (!CheckRange(S, OpPC, Ptr, CSK_Field))
return false;
if (!CheckArray(S, OpPC, Ptr))
diff --git a/clang/test/AST/ByteCode/cxx11.cpp b/clang/test/AST/ByteCode/cxx11.cpp
index 5daf6ad..cb05f26 100644
--- a/clang/test/AST/ByteCode/cxx11.cpp
+++ b/clang/test/AST/ByteCode/cxx11.cpp
@@ -202,3 +202,9 @@
// both-note {{initializer of 'g' is unknown}}
};
}
+
+namespace ExternPointer {
+ struct S { int a; };
+ extern const S pu;
+ constexpr const int *pua = &pu.a; // Ok.
+}
