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[clang][bytecode] Don't set OnePastEnd bit for array elements #136422

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Merged
merged 1 commit into from
Apr 19, 2025
Merged

[clang][bytecode] Don't set OnePastEnd bit for array elements #136422

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9 changes: 5 additions & 4 deletions clang/lib/AST/ByteCode/Pointer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -223,6 +223,7 @@ APValue Pointer::toAPValue(const ASTContext &ASTCtx) const {
UsePath = false;

// Build the path into the object.
bool OnePastEnd = isOnePastEnd();
Pointer Ptr = *this;
while (Ptr.isField() || Ptr.isArrayElement()) {

Expand Down Expand Up @@ -251,9 +252,10 @@ APValue Pointer::toAPValue(const ASTContext &ASTCtx) const {
Ptr = Ptr.expand();
const Descriptor *Desc = Ptr.getFieldDesc();
unsigned Index;
if (Ptr.isOnePastEnd())
if (Ptr.isOnePastEnd()) {
Index = Ptr.getArray().getNumElems();
else
OnePastEnd = false;
} else
Index = Ptr.getIndex();

QualType ElemType = Desc->getElemQualType();
Expand Down Expand Up @@ -304,8 +306,7 @@ APValue Pointer::toAPValue(const ASTContext &ASTCtx) const {
std::reverse(Path.begin(), Path.end());

if (UsePath)
return APValue(Base, Offset, Path,
/*IsOnePastEnd=*/!isElementPastEnd() && isOnePastEnd());
return APValue(Base, Offset, Path, OnePastEnd);

return APValue(Base, Offset, APValue::NoLValuePath());
}
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10 changes: 10 additions & 0 deletions clang/test/AST/ByteCode/arrays.cpp
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Expand Up @@ -761,3 +761,13 @@ namespace PointerSubscript {
struct S{};
static_assert((foo<S>(), true));
}

namespace OnePastEndDiag {

constexpr int a(const int *b) {
return *b; // both-note {{read of dereferenced one-past-the-end pointer}}
}
constexpr int foo[] = {1,2};
constexpr int k = a(foo + 2); // both-error {{must be initialized by a constant expression}} \
// both-note {{in call to 'a(&foo[2])'}}
}
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