[PATCH] D150209: [clang][Interp] Add more shift error checking

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: clang/test/AST/Interp/shifts.cpp:165-171
+  constexpr int negativeShift() { // cxx17-error {{never produces a constant expression}} \
+                                  // ref-cxx17-error {{never produces a constant expression}}
+    return -1 << 2; // cxx17-warning {{shifting a negative signed value is undefined}} \
+                    // ref-cxx17-warning {{shifting a negative signed value is undefined}} \
+                    // cxx17-note {{left shift of negative value -1}} \
+                    // ref-cxx17-note {{left shift of negative value -1}}
+  }
----------------
I'd like a test along the lines of:
```
constexpr int foo(int a) {
  return -a << 2;
}
static_assert(foo(10)); // Should fail
constexpr int a = -2;
static_assert(foo(a)); // Should be fine
static_assert(foo(-a)); // Should fail
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D150209/new/

https://reviews.llvm.org/D150209