Index: clang/lib/AST/Interp/Integral.h =================================================================== --- clang/lib/AST/Interp/Integral.h +++ clang/lib/AST/Interp/Integral.h @@ -234,6 +234,9 @@ } static bool neg(Integral A, Integral *R) { + if (Signed && A.isMin()) + return true; + *R = -A; return false; } Index: clang/lib/AST/Interp/Interp.h =================================================================== --- clang/lib/AST/Interp/Interp.h +++ clang/lib/AST/Interp/Interp.h @@ -425,12 +425,31 @@ template ::T> bool Neg(InterpState &S, CodePtr OpPC) { - const T &Val = S.Stk.pop(); + const T &Value = S.Stk.pop(); T Result; - T::neg(Val, &Result); + if (!T::neg(Value, &Result)) { + S.Stk.push(Result); + return true; + } + + assert(isIntegralType(Name)); S.Stk.push(Result); - return true; + + APSInt NegatedValue = -Value.toAPSInt(Value.bitWidth() + 1); + const Expr *E = S.Current->getExpr(OpPC); + QualType Type = E->getType(); + + if (S.checkingForUndefinedBehavior()) { + SmallString<32> Trunc; + NegatedValue.trunc(Result.bitWidth()).toString(Trunc, 10); + auto Loc = E->getExprLoc(); + S.report(Loc, diag::warn_integer_constant_overflow) << Trunc << Type; + return true; + } + + S.CCEDiag(E, diag::note_constexpr_overflow) << NegatedValue << Type; + return S.noteUndefinedBehavior(); } enum class PushVal : bool { Index: clang/lib/AST/Interp/PrimType.h =================================================================== --- clang/lib/AST/Interp/PrimType.h +++ clang/lib/AST/Interp/PrimType.h @@ -42,6 +42,8 @@ PT_FnPtr, }; +constexpr bool isIntegralType(PrimType T) { return T <= PT_Uint64; } + /// Mapping from primitive types to their representation. template struct PrimConv; template <> struct PrimConv { using T = Integral<8, true>; }; Index: clang/test/AST/Interp/literals.cpp =================================================================== --- clang/test/AST/Interp/literals.cpp +++ clang/test/AST/Interp/literals.cpp @@ -80,6 +80,12 @@ static_assert(~INT_MIN == INT_MAX, ""); static_assert(~INT_MAX == INT_MIN, ""); +static_assert(-(1 << 31), ""); // expected-error {{not an integral constant expression}} \ + // expected-note {{outside the range of representable values}} \ + // ref-error {{not an integral constant expression}} \ + // ref-note {{outside the range of representable values}} \ + + enum E {}; constexpr E e = static_cast(0); static_assert(~e == -1, "");