[clang] a371058 - [Clang] Diagnose ill-formed constant expression when setting a non fixed enum to a value outside the range of the enumeration values
Shafik Yaghmour via cfe-commits
cfe-commits at lists.llvm.org
Wed Jul 27 15:03:21 PDT 2022
Author: Shafik Yaghmour
Date: 2022-07-27T14:59:35-07:00
New Revision: a3710589f285de0bb22ff92b1fc24df9411e986f
URL: https://github.com/llvm/llvm-project/commit/a3710589f285de0bb22ff92b1fc24df9411e986f
DIFF: https://github.com/llvm/llvm-project/commit/a3710589f285de0bb22ff92b1fc24df9411e986f.diff
LOG: [Clang] Diagnose ill-formed constant expression when setting a non fixed enum to a value outside the range of the enumeration values
DR2338 clarified that it was undefined behavior to set the value outside the
range of the enumerations values for an enum without a fixed underlying type.
We should diagnose this with a constant expression context.
Differential Revision: https://reviews.llvm.org/D130058
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/AST/Decl.h
clang/include/clang/Basic/DiagnosticASTKinds.td
clang/lib/AST/Decl.cpp
clang/lib/AST/ExprConstant.cpp
clang/lib/CodeGen/CGExpr.cpp
clang/test/Sema/aarch64-sve-intrinsics/acle_sve_imm.cpp
clang/test/SemaCXX/constant-expression-cxx11.cpp
clang/test/SemaTemplate/temp_arg_enum_printing.cpp
clang/www/cxx_dr_status.html
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 4f5e71e0ba808..a65a41357523d 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -52,6 +52,10 @@ Bug Fixes
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+- Clang will now correctly diagnose as ill-formed a constant expression where an
+ enum without a fixed underlying type is set to a value outside the range of
+ of the enumerations values. Fixes
+ `Issue 50055: <https://github.com/llvm/llvm-project/issues/50055>`_.
Non-comprehensive list of changes in this release
-------------------------------------------------
diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index fb87a75a1241f..6441cd339d917 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -3842,6 +3842,11 @@ class EnumDecl : public TagDecl {
/// -101 1001011 8
unsigned getNumNegativeBits() const { return EnumDeclBits.NumNegativeBits; }
+ /// Calculates the [Min,Max) values the enum can store based on the
+ /// NumPositiveBits and NumNegativeBits. This matters for enums that do not
+ /// have a fixed underlying type.
+ void getValueRange(llvm::APInt &Max, llvm::APInt &Min) const;
+
/// Returns true if this is a C++11 scoped enumeration.
bool isScoped() const { return EnumDeclBits.IsScoped; }
diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td b/clang/include/clang/Basic/DiagnosticASTKinds.td
index 5e694c6ad07ba..93e4dfecc49c1 100644
--- a/clang/include/clang/Basic/DiagnosticASTKinds.td
+++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -366,6 +366,9 @@ def note_constexpr_unsupported_layout : Note<
"type %0 has unexpected layout">;
def note_constexpr_unsupported_flexible_array : Note<
"flexible array initialization is not yet supported">;
+def note_constexpr_unscoped_enum_out_of_range : Note<
+ "integer value %0 is outside the valid range of values [%1, %2) for this "
+ "enumeration type">;
def err_experimental_clang_interp_failed : Error<
"the experimental clang interpreter failed to evaluate an expression">;
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index aaba4345587b2..030792bfc7ca3 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -4621,6 +4621,21 @@ SourceRange EnumDecl::getSourceRange() const {
return Res;
}
+void EnumDecl::getValueRange(llvm::APInt &Max, llvm::APInt &Min) const {
+ unsigned Bitwidth = getASTContext().getIntWidth(getIntegerType());
+ unsigned NumNegativeBits = getNumNegativeBits();
+ unsigned NumPositiveBits = getNumPositiveBits();
+
+ if (NumNegativeBits) {
+ unsigned NumBits = std::max(NumNegativeBits, NumPositiveBits + 1);
+ Max = llvm::APInt(Bitwidth, 1) << (NumBits - 1);
+ Min = -Max;
+ } else {
+ Max = llvm::APInt(Bitwidth, 1) << NumPositiveBits;
+ Min = llvm::APInt::getZero(Bitwidth);
+ }
+}
+
//===----------------------------------------------------------------------===//
// RecordDecl Implementation
//===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 9d92c848ccb84..0f15859fc07a4 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -13519,6 +13519,34 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
}
+ if (const EnumType *ET = dyn_cast<EnumType>(DestType)) {
+ const EnumDecl *ED = ET->getDecl();
+ // Check that the value is within the range of the enumeration values.
+ //
+ // This corressponds to [expr.static.cast]p10 which says:
+ // A value of integral or enumeration type can be explicitly converted
+ // to a complete enumeration type ... If the enumeration type does not
+ // have a fixed underlying type, the value is unchanged if the original
+ // value is within the range of the enumeration values ([dcl.enum]), and
+ // otherwise, the behavior is undefined.
+ //
+ // This was resolved as part of DR2338 which has CD5 status.
+ if (!ED->isFixed()) {
+ llvm::APInt Min;
+ llvm::APInt Max;
+
+ ED->getValueRange(Max, Min);
+
+ if (ED->getNumNegativeBits() &&
+ (Max.sle(Result.getInt()) || Min.sgt(Result.getInt())))
+ CCEDiag(E, diag::note_constexpr_unscoped_enum_out_of_range)
+ << Result.getInt() << Min.getSExtValue() << Max.getSExtValue();
+ else if (!ED->getNumNegativeBits() && Max.ule(Result.getInt()))
+ CCEDiag(E, diag::note_constexpr_unscoped_enum_out_of_range)
+ << Result.getInt() << Min.getZExtValue() << Max.getZExtValue();
+ }
+ }
+
return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
Result.getInt()), E);
}
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index bf3dd812b9e8d..0b8c200335a04 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -1661,21 +1661,7 @@ static bool getRangeForType(CodeGenFunction &CGF, QualType Ty,
End = llvm::APInt(CGF.getContext().getTypeSize(Ty), 2);
} else {
const EnumDecl *ED = ET->getDecl();
- llvm::Type *LTy = CGF.ConvertTypeForMem(ED->getIntegerType());
- unsigned Bitwidth = LTy->getScalarSizeInBits();
- unsigned NumNegativeBits = ED->getNumNegativeBits();
- unsigned NumPositiveBits = ED->getNumPositiveBits();
-
- if (NumNegativeBits) {
- unsigned NumBits = std::max(NumNegativeBits, NumPositiveBits + 1);
- assert(NumBits <= Bitwidth);
- End = llvm::APInt(Bitwidth, 1) << (NumBits - 1);
- Min = -End;
- } else {
- assert(NumPositiveBits <= Bitwidth);
- End = llvm::APInt(Bitwidth, 1) << NumPositiveBits;
- Min = llvm::APInt::getZero(Bitwidth);
- }
+ ED->getValueRange(End, Min);
}
return true;
}
diff --git a/clang/test/Sema/aarch64-sve-intrinsics/acle_sve_imm.cpp b/clang/test/Sema/aarch64-sve-intrinsics/acle_sve_imm.cpp
index 7be8aec449c9f..cfd3b3685a0c7 100644
--- a/clang/test/Sema/aarch64-sve-intrinsics/acle_sve_imm.cpp
+++ b/clang/test/Sema/aarch64-sve-intrinsics/acle_sve_imm.cpp
@@ -206,19 +206,19 @@ void test_range_0_13(svbool_t pg, const void *const_void_ptr)
{
// expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
svprfb(pg, const_void_ptr, svprfop(14));
- // expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
+ // expected-error-re at +1 {{must be a constant integer}}
svprfb_vnum(pg, const_void_ptr, 0, svprfop(-1));
// expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
svprfd(pg, const_void_ptr, svprfop(14));
- // expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
+ // expected-error-re at +1 {{must be a constant integer}}
svprfd_vnum(pg, const_void_ptr, 0, svprfop(-1));
// expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
svprfh(pg, const_void_ptr, svprfop(14));
- // expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
+ // expected-error-re at +1 {{must be a constant integer}}
svprfh_vnum(pg, const_void_ptr, 0, svprfop(-1));
// expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
svprfw(pg, const_void_ptr, svprfop(14));
- // expected-error-re at +1 {{argument value {{[0-9]+}} is outside the valid range [0, 13]}}
+ // expected-error-re at +1 {{must be a constant integer}}
svprfw_vnum(pg, const_void_ptr, 0, svprfop(-1));
}
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index e0163fe1f2bb1..d97c27426b94a 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -2399,3 +2399,50 @@ void local_constexpr_var() {
constexpr int a = 0; // expected-note {{address of non-static constexpr variable 'a' may
diff er on each invocation of the enclosing function; add 'static' to give it a constant address}}
constexpr const int *p = &a; // expected-error {{constant expression}} expected-note {{pointer to 'a' is not a constant expression}}
}
+
+namespace GH50055 {
+// Enums without fixed underlying type
+enum E1 {e11=-4, e12=4};
+enum E2 {e21=0, e22=4};
+enum E3 {e31=-4, e32=1024};
+enum E4 {e41=0};
+// Empty but as-if it had a single enumerator with value 0
+enum EEmpty {};
+
+// Enum with fixed underlying type because the underlying type is explicitly specified
+enum EFixed : int {efixed1=-4, efixed2=4};
+// Enum with fixed underlying type because it is scoped
+enum class EScoped {escoped1=-4, escoped2=4};
+
+void testValueInRangeOfEnumerationValues() {
+ constexpr E1 x1 = static_cast<E1>(-8);
+ constexpr E1 x2 = static_cast<E1>(8); // expected-error {{must be initialized by a constant expression}}
+ // expected-note at -1 {{integer value 8 is outside the valid range of values [-8, 8) for this enumeration type}}
+
+ constexpr E2 x3 = static_cast<E2>(-8); // expected-error {{must be initialized by a constant expression}}
+ // expected-note at -1 {{integer value -8 is outside the valid range of values [0, 8) for this enumeration type}}
+ constexpr E2 x4 = static_cast<E2>(0);
+ constexpr E2 x5 = static_cast<E2>(8); // expected-error {{must be initialized by a constant expression}}
+ // expected-note at -1 {{integer value 8 is outside the valid range of values [0, 8) for this enumeration type}}
+
+ constexpr E3 x6 = static_cast<E3>(-2048);
+ constexpr E3 x7 = static_cast<E3>(-8);
+ constexpr E3 x8 = static_cast<E3>(0);
+ constexpr E3 x9 = static_cast<E3>(8);
+ constexpr E3 x10 = static_cast<E3>(2048); // expected-error {{must be initialized by a constant expression}}
+ // expected-note at -1 {{integer value 2048 is outside the valid range of values [-2048, 2048) for this enumeration type}}
+
+ constexpr E4 x11 = static_cast<E4>(0);
+ constexpr E4 x12 = static_cast<E4>(1);
+ constexpr E4 x13 = static_cast<E4>(2); // expected-error {{must be initialized by a constant expression}}
+ // expected-note at -1 {{integer value 2 is outside the valid range of values [0, 2) for this enumeration type}}
+
+ constexpr EEmpty x14 = static_cast<EEmpty>(0);
+ constexpr EEmpty x15 = static_cast<EEmpty>(1);
+ constexpr EEmpty x16 = static_cast<EEmpty>(2); // expected-error {{must be initialized by a constant expression}}
+ // expected-note at -1 {{integer value 2 is outside the valid range of values [0, 2) for this enumeration type}}
+
+ constexpr EFixed x17 = static_cast<EFixed>(100);
+ constexpr EScoped x18 = static_cast<EScoped>(100);
+}
+}
diff --git a/clang/test/SemaTemplate/temp_arg_enum_printing.cpp b/clang/test/SemaTemplate/temp_arg_enum_printing.cpp
index c5570af82bc84..5a486edd2d30d 100644
--- a/clang/test/SemaTemplate/temp_arg_enum_printing.cpp
+++ b/clang/test/SemaTemplate/temp_arg_enum_printing.cpp
@@ -3,7 +3,7 @@
namespace NamedEnumNS
{
-enum NamedEnum
+enum class NamedEnum
{
Val0,
Val1
@@ -13,9 +13,9 @@ template <NamedEnum E>
void foo();
void test() {
- // CHECK: template<> void foo<NamedEnumNS::Val0>()
- NamedEnumNS::foo<Val0>();
- // CHECK: template<> void foo<NamedEnumNS::Val1>()
+ // CHECK: template<> void foo<NamedEnumNS::NamedEnum::Val0>()
+ NamedEnumNS::foo<NamedEnum::Val0>();
+ // CHECK: template<> void foo<NamedEnumNS::NamedEnum::Val1>()
NamedEnumNS::foo<(NamedEnum)1>();
// CHECK: template<> void foo<(NamedEnumNS::NamedEnum)2>()
NamedEnumNS::foo<(NamedEnum)2>();
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 466f287c75d90..f3cfe9faea150 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -13842,7 +13842,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
<td><a href="https://wg21.link/cwg2338">2338</a></td>
<td>CD5</td>
<td>Undefined behavior converting to short enums with fixed underlying types</td>
- <td class="full" align="center">Clang 12</td>
+ <td class="full" align="center">Clang 16</td>
</tr>
<tr id="2339">
<td><a href="https://wg21.link/cwg2339">2339</a></td>
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