diff --git a/include/clang/Basic/DiagnosticASTKinds.td b/include/clang/Basic/DiagnosticASTKinds.td
index b3cba2066edd8248d84d304ac757657b5c8a5d9d..215580b2e9b6669779ee89b0c0e63bbc7edab45f 100644
--- a/include/clang/Basic/DiagnosticASTKinds.td
+++ b/include/clang/Basic/DiagnosticASTKinds.td
@@ -127,6 +127,10 @@ def note_constexpr_access_null : Note<
def note_constexpr_access_past_end : Note<
"%select{read of|assignment to|increment of|decrement of}0 "
"dereferenced one-past-the-end pointer is not allowed in a constant expression">;
+def note_constexpr_access_unsized_array : Note<
+ "%select{read of|assignment to|increment of|decrement of}0 "
+ "pointer to element of array without known bound "
+ "is not allowed in a constant expression">;
def note_constexpr_access_inactive_union_member : Note<
"%select{read of|assignment to|increment of|decrement of}0 "
"member %1 of union with %select{active member %3|no active member}2 "
@@ -154,6 +158,11 @@ def note_constexpr_baa_insufficient_alignment : Note<
def note_constexpr_baa_value_insufficient_alignment : Note<
"value of the aligned pointer (%0) is not a multiple of the asserted %1 "
"%plural{1:byte|:bytes}1">;
+def note_constexpr_unsupported_unsized_array : Note<
+ "array-to-pointer decay of array member without known bound is not supported">;
+def note_constexpr_unsized_array_indexed : Note<
+ "indexing of array without known bound is not allowed "
+ "in a constant expression">;
def warn_integer_constant_overflow : Warning<
"overflow in expression; result is %0 with type %1">,
diff --git a/include/clang/Basic/DiagnosticIDs.h b/include/clang/Basic/DiagnosticIDs.h
index ca04ccacf603e93dd480c20c4088ea728532682f..a62d6af744c91a2db580eda31170e9b028b9117f 100644
--- a/include/clang/Basic/DiagnosticIDs.h
+++ b/include/clang/Basic/DiagnosticIDs.h
@@ -34,7 +34,7 @@ namespace clang {
DIAG_SIZE_SERIALIZATION = 120,
DIAG_SIZE_LEX = 400,
DIAG_SIZE_PARSE = 500,
- DIAG_SIZE_AST = 110,
+ DIAG_SIZE_AST = 150,
DIAG_SIZE_COMMENT = 100,
DIAG_SIZE_CROSSTU = 100,
DIAG_SIZE_SEMA = 3500,
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index ecce50ed23cc27766d5af7434b340a6f437110c8..c25b3b6322fe5c1e7f0f562fad51f63b77cd1d90 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -62,7 +62,13 @@ namespace {
static QualType getType(APValue::LValueBase B) {
if (!B) return QualType();
if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>())
- return D->getType();
+ // FIXME: It's unclear where we're supposed to take the type from, and
+ // this actually matters for arrays of unknown bound. Using the type of
+ // the most recent declaration isn't clearly correct in general. Eg:
+ //
+ // extern int arr[]; void f() { extern int arr[3]; };
+ // constexpr int *p = &arr[1]; // valid?
+ return cast<ValueDecl>(D->getMostRecentDecl())->getType();
const Expr *Base = B.get<const Expr*>();
@@ -141,6 +147,12 @@ namespace {
return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
}
+ /// The bound to claim that an array of unknown bound has.
+ /// The value in MostDerivedArraySize is undefined in this case. So, set it
+ /// to an arbitrary value that's likely to loudly break things if it's used.
+ static const uint64_t AssumedSizeForUnsizedArray =
+ std::numeric_limits<uint64_t>::max() / 2;
+
/// Determines if an LValue with the given LValueBase will have an unsized
/// array in its designator.
/// Find the path length and type of the most-derived subobject in the given
@@ -148,7 +160,8 @@ namespace {
static unsigned
findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
ArrayRef<APValue::LValuePathEntry> Path,
- uint64_t &ArraySize, QualType &Type, bool &IsArray) {
+ uint64_t &ArraySize, QualType &Type, bool &IsArray,
+ bool &FirstEntryIsUnsizedArray) {
// This only accepts LValueBases from APValues, and APValues don't support
// arrays that lack size info.
assert(!isBaseAnAllocSizeCall(Base) &&
@@ -158,12 +171,18 @@ namespace {
for (unsigned I = 0, N = Path.size(); I != N; ++I) {
if (Type->isArrayType()) {
- const ConstantArrayType *CAT =
- cast<ConstantArrayType>(Ctx.getAsArrayType(Type));
- Type = CAT->getElementType();
- ArraySize = CAT->getSize().getZExtValue();
+ const ArrayType *AT = Ctx.getAsArrayType(Type);
+ Type = AT->getElementType();
MostDerivedLength = I + 1;
IsArray = true;
+
+ if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
+ ArraySize = CAT->getSize().getZExtValue();
+ } else {
+ assert(I == 0 && "unexpected unsized array designator");
+ FirstEntryIsUnsizedArray = true;
+ ArraySize = AssumedSizeForUnsizedArray;
+ }
} else if (Type->isAnyComplexType()) {
const ComplexType *CT = Type->castAs<ComplexType>();
Type = CT->getElementType();
@@ -246,10 +265,12 @@ namespace {
Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
if (V.getLValueBase()) {
bool IsArray = false;
+ bool FirstIsUnsizedArray = false;
MostDerivedPathLength = findMostDerivedSubobject(
Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
- MostDerivedType, IsArray);
+ MostDerivedType, IsArray, FirstIsUnsizedArray);
MostDerivedIsArrayElement = IsArray;
+ FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
}
}
}
@@ -318,7 +339,7 @@ namespace {
// The value in MostDerivedArraySize is undefined in this case. So, set it
// to an arbitrary value that's likely to loudly break things if it's
// used.
- MostDerivedArraySize = std::numeric_limits<uint64_t>::max() / 2;
+ MostDerivedArraySize = AssumedSizeForUnsizedArray;
MostDerivedPathLength = Entries.size();
}
/// Update this designator to refer to the given base or member of this
@@ -350,6 +371,7 @@ namespace {
MostDerivedArraySize = 2;
MostDerivedPathLength = Entries.size();
}
+ void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
const APSInt &N);
/// Add N to the address of this subobject.
@@ -357,6 +379,7 @@ namespace {
if (Invalid || !N) return;
uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
if (isMostDerivedAnUnsizedArray()) {
+ diagnoseUnsizedArrayPointerArithmetic(Info, E);
// Can't verify -- trust that the user is doing the right thing (or if
// not, trust that the caller will catch the bad behavior).
// FIXME: Should we reject if this overflows, at least?
@@ -1094,9 +1117,19 @@ bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
setInvalid();
return false;
}
+ // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
+ // must actually be at least one array element; even a VLA cannot have a
+ // bound of zero. And if our index is nonzero, we already had a CCEDiag.
return true;
}
+void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
+ const Expr *E) {
+ Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
+ // Do not set the designator as invalid: we can represent this situation,
+ // and correct handling of __builtin_object_size requires us to do so.
+}
+
void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
const Expr *E,
const APSInt &N) {
@@ -1240,8 +1273,6 @@ namespace {
IsNullPtr);
else {
assert(!InvalidBase && "APValues can't handle invalid LValue bases");
- assert(!Designator.FirstEntryIsAnUnsizedArray &&
- "Unsized array with a valid base?");
V = APValue(Base, Offset, Designator.Entries,
Designator.IsOnePastTheEnd, CallIndex, IsNullPtr);
}
@@ -1314,10 +1345,14 @@ namespace {
if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
Designator.addDeclUnchecked(D, Virtual);
}
- void addUnsizedArray(EvalInfo &Info, QualType ElemTy) {
- assert(Designator.Entries.empty() && getType(Base)->isPointerType());
- assert(isBaseAnAllocSizeCall(Base) &&
- "Only alloc_size bases can have unsized arrays");
+ void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
+ if (!Designator.Entries.empty()) {
+ Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
+ Designator.setInvalid();
+ return;
+ }
+
+ assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
Designator.FirstEntryIsAnUnsizedArray = true;
Designator.addUnsizedArrayUnchecked(ElemTy);
}
@@ -2624,10 +2659,12 @@ findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
if (Sub.Invalid)
// A diagnostic will have already been produced.
return handler.failed();
- if (Sub.isOnePastTheEnd()) {
+ if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
if (Info.getLangOpts().CPlusPlus11)
- Info.FFDiag(E, diag::note_constexpr_access_past_end)
- << handler.AccessKind;
+ Info.FFDiag(E, Sub.isOnePastTheEnd()
+ ? diag::note_constexpr_access_past_end
+ : diag::note_constexpr_access_unsized_array)
+ << handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
@@ -5487,7 +5524,7 @@ static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
Result.setInvalid(E);
QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
- Result.addUnsizedArray(Info, Pointee);
+ Result.addUnsizedArray(Info, E, Pointee);
return true;
}
@@ -5697,7 +5734,8 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
return true;
}
}
- case CK_ArrayToPointerDecay:
+
+ case CK_ArrayToPointerDecay: {
if (SubExpr->isGLValue()) {
if (!evaluateLValue(SubExpr, Result))
return false;
@@ -5708,12 +5746,13 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
return false;
}
// The result is a pointer to the first element of the array.
- if (const ConstantArrayType *CAT
- = Info.Ctx.getAsConstantArrayType(SubExpr->getType()))
+ auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
+ if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
Result.addArray(Info, E, CAT);
else
- Result.Designator.setInvalid();
+ Result.addUnsizedArray(Info, E, AT->getElementType());
return true;
+ }
case CK_FunctionToPointerDecay:
return evaluateLValue(SubExpr, Result);
@@ -5780,7 +5819,7 @@ bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
Result.setInvalid(E);
QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
- Result.addUnsizedArray(Info, PointeeTy);
+ Result.addUnsizedArray(Info, E, PointeeTy);
return true;
}
@@ -7341,7 +7380,8 @@ static const Expr *ignorePointerCastsAndParens(const Expr *E) {
/// Please note: this function is specialized for how __builtin_object_size
/// views "objects".
///
-/// If this encounters an invalid RecordDecl, it will always return true.
+/// If this encounters an invalid RecordDecl or otherwise cannot determine the
+/// correct result, it will always return true.
static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
assert(!LVal.Designator.Invalid);
@@ -7372,9 +7412,8 @@ static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
unsigned I = 0;
QualType BaseType = getType(Base);
if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
- assert(isBaseAnAllocSizeCall(Base) &&
- "Unsized array in non-alloc_size call?");
- // If this is an alloc_size base, we should ignore the initial array index
+ // If we don't know the array bound, conservatively assume we're looking at
+ // the final array element.
++I;
BaseType = BaseType->castAs<PointerType>()->getPointeeType();
}
diff --git a/test/SemaCXX/constant-expression-cxx11.cpp b/test/SemaCXX/constant-expression-cxx11.cpp
index e64f2d5a335dc229796a63ce1165b9944ee2546c..68b82c7d96fdd956822af6f6a9e436657b421252 100644
--- a/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/test/SemaCXX/constant-expression-cxx11.cpp
@@ -604,20 +604,31 @@ static_assert(NATDCArray{}[1][1].n == 0, "");
}
-// Tests for indexes into arrays of unknown bounds.
+// Per current CWG direction, we reject any cases where pointer arithmetic is
+// not statically known to be valid.
namespace ArrayOfUnknownBound {
- // This is a corner case of the language where it's not clear whether this
- // should be an error: When we see the initializer for Z::a, the bounds of
- // Z::b aren't known yet, but they will be known by the end of the translation
- // unit, so the compiler can in theory check the indexing into Z::b.
- // For the time being, as long as this is unclear, we want to make sure that
- // this compiles.
- struct Z {
- static const void *const a[];
- static const void *const b[];
+ extern int arr[];
+ constexpr int *a = arr;
+ constexpr int *b = &arr[0];
+ static_assert(a == b, "");
+ constexpr int *c = &arr[1]; // expected-error {{constant}} expected-note {{indexing of array without known bound}}
+ constexpr int *d = &a[1]; // expected-error {{constant}} expected-note {{indexing of array without known bound}}
+ constexpr int *e = a + 1; // expected-error {{constant}} expected-note {{indexing of array without known bound}}
+
+ struct X {
+ int a;
+ int b[]; // expected-warning {{C99}}
};
- constexpr const void *Z::a[] = {&b[0], &b[1]};
- constexpr const void *Z::b[] = {&a[0], &a[1]};
+ extern X x;
+ constexpr int *xb = x.b; // expected-error {{constant}} expected-note {{not supported}}
+
+ struct Y { int a; };
+ extern Y yarr[];
+ constexpr Y *p = yarr;
+ constexpr int *q = &p->a;
+
+ extern const int carr[]; // expected-note {{here}}
+ constexpr int n = carr[0]; // expected-error {{constant}} expected-note {{non-constexpr variable}}
}
namespace DependentValues {
diff --git a/test/SemaCXX/constexpr-array-unknown-bound.cpp b/test/SemaCXX/constexpr-array-unknown-bound.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..395c4cbd127b24832ef1ae2fb22e70ff00b5dd13
--- /dev/null
+++ b/test/SemaCXX/constexpr-array-unknown-bound.cpp
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 %s -Wno-uninitialized -std=c++1z -fsyntax-only -verify
+
+const extern int arr[];
+constexpr auto p = arr; // ok
+constexpr int f(int i) {return p[i];} // expected-note {{read of dereferenced one-past-the-end pointer}}
+
+constexpr int arr[] {1, 2, 3};
+constexpr auto p2 = arr + 2; // ok
+constexpr int x = f(2); // ok
+constexpr int y = f(3); // expected-error {{constant expression}}
+// expected-note-re@-1 {{in call to 'f({{.*}})'}}
+
+// FIXME: consider permitting this case
+struct A {int m[];} a;
+constexpr auto p3 = a.m; // expected-error {{constant expression}} expected-note {{without known bound}}
+constexpr auto p4 = a.m + 1; // expected-error {{constant expression}} expected-note {{without known bound}}
+
+void g(int i) {
+ int arr[i];
+ constexpr auto *p = arr + 2; // expected-error {{constant expression}} expected-note {{without known bound}}
+
+ // FIXME: Give a better diagnostic here. The issue is that computing
+ // sizeof(*arr2) within the array indexing fails due to the VLA.
+ int arr2[2][i];
+ constexpr int m = ((void)arr2[2], 0); // expected-error {{constant expression}}
+}
diff --git a/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp b/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
index c1fcedd58d1344c8c0648c2ae219b1dd48215af8..d0fb25c047a9610fe4f3995a53047877031b775b 100644
--- a/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
+++ b/test/SemaTemplate/temp_arg_nontype_cxx1z.cpp
@@ -23,6 +23,9 @@ namespace Array {
A<const char*, &(&x)[1]> h; // expected-error {{refers to subobject '&x + 1'}}
A<const char*, 0> i; // expected-error {{not allowed in a converted constant}}
A<const char*, nullptr> j;
+
+ extern char aub[];
+ A<char[], aub> k;
}
namespace Function {