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[clang][Interp] Diagnose out-of-range casts to enum types
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‎clang/lib/AST/Interp/Compiler.cpp‎

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -466,6 +466,16 @@ bool Compiler<Emitter>::VisitCastExpr(const CastExpr *CE) {
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if (!this->visit(SubExpr))
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return false;
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469+
// Possibly diagnose casts to enum types if the target type does not
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// have a fixed size.
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if (CE->getType()->isEnumeralType()) {
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if (const auto *ET = CE->getType().getCanonicalType()->getAs<EnumType>();
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ET && !ET->getDecl()->isFixed()) {
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if (!this->emitCheckEnumValue(*FromT, ET->getDecl(), CE))
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return false;
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}
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}
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if (ToT == PT_IntAP)
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return this->emitCastAP(*FromT, Ctx.getBitWidth(CE->getType()), CE);
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if (ToT == PT_IntAPS)

‎clang/lib/AST/Interp/Interp.cpp‎

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Original file line numberDiff line numberDiff line change
@@ -22,6 +22,7 @@
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#include "clang/AST/Expr.h"
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#include "clang/AST/ExprCXX.h"
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#include "llvm/ADT/APSInt.h"
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#include "llvm/ADT/StringExtras.h"
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#include <limits>
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#include <vector>
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@@ -899,6 +900,31 @@ bool RunDestructors(InterpState &S, CodePtr OpPC, const Block *B) {
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return runRecordDestructor(S, OpPC, Pointer(const_cast<Block *>(B)), Desc);
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}
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void diagnoseEnumValue(InterpState &S, CodePtr OpPC, const EnumDecl *ED,
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const APSInt &Value) {
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llvm::APInt Min;
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llvm::APInt Max;
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if (S.EvaluatingDecl && !S.EvaluatingDecl->isConstexpr())
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return;
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ED->getValueRange(Max, Min);
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--Max;
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if (ED->getNumNegativeBits() &&
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(Max.slt(Value.getSExtValue()) || Min.sgt(Value.getSExtValue()))) {
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const SourceLocation &Loc = S.Current->getLocation(OpPC);
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S.report(Loc, diag::warn_constexpr_unscoped_enum_out_of_range)
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<< llvm::toString(Value, 10) << Min.getSExtValue() << Max.getSExtValue()
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<< ED;
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} else if (!ED->getNumNegativeBits() && Max.ult(Value.getZExtValue())) {
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const SourceLocation &Loc = S.Current->getLocation(OpPC);
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S.report(Loc, diag::warn_constexpr_unscoped_enum_out_of_range)
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<< llvm::toString(Value, 10) << Min.getZExtValue() << Max.getZExtValue()
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<< ED;
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}
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}
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bool Interpret(InterpState &S, APValue &Result) {
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// The current stack frame when we started Interpret().
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// This is being used by the ops to determine wheter

‎clang/lib/AST/Interp/Interp.h‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2774,6 +2774,20 @@ inline bool CheckNonNullArg(InterpState &S, CodePtr OpPC) {
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return false;
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}
27762776

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void diagnoseEnumValue(InterpState &S, CodePtr OpPC, const EnumDecl *ED,
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const APSInt &Value);
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template <PrimType Name, class T = typename PrimConv<Name>::T>
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inline bool CheckEnumValue(InterpState &S, CodePtr OpPC, const EnumDecl *ED) {
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assert(ED);
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assert(!ED->isFixed());
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const APSInt Val = S.Stk.peek<T>().toAPSInt();
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if (S.inConstantContext())
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diagnoseEnumValue(S, OpPC, ED, Val);
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return true;
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}
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/// OldPtr -> Integer -> NewPtr.
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template <PrimType TIn, PrimType TOut>
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inline bool DecayPtr(InterpState &S, CodePtr OpPC) {

‎clang/lib/AST/Interp/Opcodes.td‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -66,6 +66,7 @@ def ArgDecl : ArgType { let Name = "const Decl*"; }
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def ArgVarDecl : ArgType { let Name = "const VarDecl*"; }
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def ArgDesc : ArgType { let Name = "const Descriptor *"; }
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def ArgPrimType : ArgType { let Name = "PrimType"; }
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def ArgEnumDecl : ArgType { let Name = "const EnumDecl *"; }
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//===----------------------------------------------------------------------===//
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// Classes of types instructions operate on.
@@ -389,6 +390,12 @@ def CheckDecl : Opcode {
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let Args = [ArgVarDecl];
390391
}
391392

393+
def CheckEnumValue : Opcode {
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let Args = [ArgEnumDecl];
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let Types = [FixedSizeIntegralTypeClass];
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let HasGroup = 1;
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}
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392399
// [] -> [Value]
393400
def GetGlobal : AccessOpcode;
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def GetGlobalUnchecked : AccessOpcode;

‎clang/test/AST/Interp/cxx11.cpp‎

Lines changed: 90 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -62,3 +62,93 @@ namespace ReferenceToConst {
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}
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};
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}
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namespace GH50055 {
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// Enums without fixed underlying type
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enum E1 {e11=-4, e12=4};
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enum E2 {e21=0, e22=4};
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enum E3 {e31=-4, e32=1024};
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enum E4 {e41=0};
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// Empty but as-if it had a single enumerator with value 0
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enum EEmpty {};
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// Enum with fixed underlying type because the underlying type is explicitly specified
78+
enum EFixed : int {efixed1=-4, efixed2=4};
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// Enum with fixed underlying type because it is scoped
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enum class EScoped {escoped1=-4, escoped2=4};
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enum EMaxInt {emaxint1=-1, emaxint2=__INT_MAX__};
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enum NumberType {};
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E2 testDefaultArgForParam(E2 e2Param = (E2)-1) { // ok, not a constant expression context
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E2 e2LocalInit = e2Param; // ok, not a constant expression context
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return e2LocalInit;
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}
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// #include <enum-constexpr-conversion-system-header.h>
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void testValueInRangeOfEnumerationValues() {
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constexpr E1 x1 = static_cast<E1>(-8);
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constexpr E1 x2 = static_cast<E1>(8);
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// both-error@-1 {{integer value 8 is outside the valid range of values [-8, 7] for the enumeration type 'E1'}}
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E1 x2b = static_cast<E1>(8); // ok, not a constant expression context
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constexpr E2 x3 = static_cast<E2>(-8);
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// both-error@-1 {{integer value -8 is outside the valid range of values [0, 7] for the enumeration type 'E2'}}
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constexpr E2 x4 = static_cast<E2>(0);
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constexpr E2 x5 = static_cast<E2>(8);
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// both-error@-1 {{integer value 8 is outside the valid range of values [0, 7] for the enumeration type 'E2'}}
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constexpr E3 x6 = static_cast<E3>(-2048);
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constexpr E3 x7 = static_cast<E3>(-8);
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constexpr E3 x8 = static_cast<E3>(0);
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constexpr E3 x9 = static_cast<E3>(8);
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constexpr E3 x10 = static_cast<E3>(2048);
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// both-error@-1 {{integer value 2048 is outside the valid range of values [-2048, 2047] for the enumeration type 'E3'}}
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constexpr E4 x11 = static_cast<E4>(0);
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constexpr E4 x12 = static_cast<E4>(1);
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constexpr E4 x13 = static_cast<E4>(2);
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// both-error@-1 {{integer value 2 is outside the valid range of values [0, 1] for the enumeration type 'E4'}}
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constexpr EEmpty x14 = static_cast<EEmpty>(0);
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constexpr EEmpty x15 = static_cast<EEmpty>(1);
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constexpr EEmpty x16 = static_cast<EEmpty>(2);
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// both-error@-1 {{integer value 2 is outside the valid range of values [0, 1] for the enumeration type 'EEmpty'}}
121+
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constexpr EFixed x17 = static_cast<EFixed>(100);
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constexpr EScoped x18 = static_cast<EScoped>(100);
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constexpr EMaxInt x19 = static_cast<EMaxInt>(__INT_MAX__-1);
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constexpr EMaxInt x20 = static_cast<EMaxInt>((long)__INT_MAX__+1);
127+
// both-error@-1 {{integer value 2147483648 is outside the valid range of values [-2147483648, 2147483647] for the enumeration type 'EMaxInt'}}
128+
129+
const NumberType neg_one = (NumberType) ((NumberType) 0 - (NumberType) 1); // ok, not a constant expression context
130+
}
131+
132+
template<class T, unsigned size> struct Bitfield {
133+
static constexpr T max = static_cast<T>((1 << size) - 1); // #enum
134+
};
135+
136+
void testValueInRangeOfEnumerationValuesViaTemplate() {
137+
Bitfield<E2, 3> good;
138+
Bitfield<E2, 4> bad; // both-error@#enum {{integer value 15 is outside the valid range of values [0, 7] for the enumeration type 'E2'}}
139+
}
140+
141+
enum SortOrder {
142+
AscendingOrder,
143+
DescendingOrder
144+
};
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146+
class A {
147+
static void f(SortOrder order);
148+
};
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void A::f(SortOrder order) {
151+
if (order == SortOrder(-1)) // ok, not a constant expression context
152+
return;
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}
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}

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