[clang][Interp] Handle enums

Handle DeclRefExprs of enum types. They are otherwise handled like
integers.

Differential Revision: https://reviews.llvm.org/D134020

diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
index 5974678..9264357 100644 (file)
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -861,6 +861,11 @@ bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
 
       FoundDecl = true;
     }
+  } else if (const auto *ECD = dyn_cast<EnumConstantDecl>(Decl)) {
+    PrimType T = *classify(ECD->getType());
+
+    return this->emitConst(T, getIntWidth(ECD->getType()), ECD->getInitVal(),
+                           E);
   }
 
   // References are implemented using pointers, so when we get here,

diff --git a/clang/test/AST/Interp/enums.cpp b/clang/test/AST/Interp/enums.cpp
new file mode 100644 (file)
index 0000000..adb09e5
--- /dev/null
+++ b/clang/test/AST/Interp/enums.cpp
@@ -0,0 +1,57 @@
+// RUN: %clang_cc1 -fexperimental-new-constant-interpreter -verify %s
+// RUN: %clang_cc1 -verify=ref %s
+
+enum class EC : short {
+  A, B, C
+};
+static_assert(static_cast<int>(EC::A) == 0, "");
+static_assert(static_cast<int>(EC::B) == 1, "");
+static_assert(static_cast<int>(EC::C) == 2, "");
+static_assert(sizeof(EC) == sizeof(short), "");
+
+constexpr EC ec = EC::C;
+static_assert(static_cast<int>(ec) == 2, "");
+
+constexpr int N = 12;
+constexpr int M = 2;
+
+enum CE {
+  ONE = -1,
+  TWO = 2,
+  THREE,
+  FOUR = 4,
+  FIVE = N + M,
+  SIX = FIVE + 2,
+  MAX = __INT_MAX__ * 2U + 1U
+};
+static_assert(ONE == -1, "");
+static_assert(THREE == 3, "");
+static_assert(FIVE == 14, "");
+static_assert(SIX == 16, "");
+
+constexpr EC testEnums() {
+  EC e = EC::C;
+
+  e = EC::B;
+
+  EC::B = e; // expected-error{{expression is not assignable}} \
+             // ref-error{{expression is not assignable}}
+
+  return e;
+}
+
+constexpr EC getB() {
+  EC e = EC::C;
+  e = EC::B;
+  return e;
+}
+
+
+static_assert(getB() == EC::B, "");
+
+
+enum E { // expected-warning{{enumeration values exceed range of largest integer}} \
+         // ref-warning{{enumeration values exceed range of largest integer}}
+  E1 = -__LONG_MAX__ -1L,
+  E2 = __LONG_MAX__ *2UL+1UL
+};