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[clang][bytecode] Guard strcmp against differing element types #154777

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Merged
tbaederr merged 1 commit into from
Aug 21, 2025
Merged

[clang][bytecode] Guard strcmp against differing element types #154777

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7 changes: 6 additions & 1 deletion clang/lib/AST/ByteCode/InterpBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -205,14 +205,19 @@ static bool interp__builtin_strcmp(InterpState &S, CodePtr OpPC,

if (A.isDummy() || B.isDummy())
return false;
if (!A.isBlockPointer() || !B.isBlockPointer())
return false;

bool IsWide = ID == Builtin::BIwcscmp || ID == Builtin::BIwcsncmp ||
ID == Builtin::BI__builtin_wcscmp ||
ID == Builtin::BI__builtin_wcsncmp;
assert(A.getFieldDesc()->isPrimitiveArray());
assert(B.getFieldDesc()->isPrimitiveArray());

assert(getElemType(A).getTypePtr() == getElemType(B).getTypePtr());
// Different element types shouldn't happen, but with casts they can.
if (!S.getASTContext().hasSameUnqualifiedType(getElemType(A), getElemType(B)))
return false;

PrimType ElemT = *S.getContext().classify(getElemType(A));

auto returnResult = [&](int V) -> bool {
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9 changes: 9 additions & 0 deletions clang/test/AST/ByteCode/c.c
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Expand Up @@ -338,3 +338,12 @@ static void *FooTable[1] = {
}
};

int strcmp(const char *, const char *); // all-note {{passing argument to parameter here}}
#define S "\x01\x02\x03\x04\x05\x06\x07\x08"
const char _str[] = {S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7]};
const unsigned char _str2[] = {S[0], S[1], S[2], S[3], S[4], S[5], S[6], S[7]};
const int compared = strcmp(_str, (const char *)_str2); // all-error {{initializer element is not a compile-time constant}}
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@shafik shafik Aug 25, 2025

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Isn't this reject b/c of the reinterpret_cast? While the change is about the guard in interp__builtin_strcmp? Am I missing something?

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@tbaederr tbaederr Aug 25, 2025

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The cast causes a CCEDiag but we continue evaluation so it reaches the __builtin_strcmp.



const int compared2 = strcmp(strcmp, _str); // all-warning {{incompatible pointer types}} \
// all-error {{initializer element is not a compile-time constant}}