================
@@ -11,6 +11,25 @@
// cxx98-error@-1 {{variadic macros are a C99 feature}}
#endif
+namespace cwg1504 { // cwg1504: 23
+#if __cplusplus >= 201103L
+ // CWG1504: Pointer arithmetic after derived-base conversion
+ struct Base { int x; };
+ struct Derived : Base { int y; };
+ constexpr Derived arr[2] = {};
+
+ // Pointer arithmetic on a base pointer into a derived array is UB,
+ // and the constexpr evaluator must diagnose it.
+ constexpr int test(int n) {
+ return ((const Base*)arr)[n].x; // #cwg1504-x
+ }
+ constexpr int bad = test(1);
+ // since-cxx11-error@-1 {{constexpr variable 'bad' must be initialized by a
constant expression}}
+ // since-cxx11-note@#cwg1504-x {{cannot access field of pointer past the end
of object}}
+ // since-cxx11-note@-3 {{in call to 'test(1)'}}
----------------
zwuis wrote:
```suggestion
// since-cxx11-note@#cwg1504-x {{cannot access field of pointer past the
end of object}}
// since-cxx11-note@-3 {{in call to 'test(1)'}}
```
https://clang.llvm.org/docs/InternalsManual.html#c-defect-report-tests
https://github.com/llvm/llvm-project/pull/209593
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