https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/154777
This can happen when casts are involved.
Fixes #154006
>From 493eb4549b7e4ac5a72d01d4656e6ab0f557f2f1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Thu, 21 Aug 2025 16:54:58 +0200
Subject: [PATCH] [clang][bytecode] Guard strcmp against differing element
types
This can happen when casts are involved.
Fixes #154006
---
clang/lib/AST/ByteCode/InterpBuiltin.cpp | 7 ++++++-
clang/test/AST/ByteCode/c.c | 9 +++++++++
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index 2cbebaf7b630e..7516694be8da7 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -205,6 +205,8 @@ 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 ||
@@ -212,7 +214,10 @@ static bool interp__builtin_strcmp(InterpState &S, CodePtr
OpPC,
assert(A.getFieldDesc()->isPrimitiveArray());
assert(B.getFieldDesc()->isPrimitiveArray());
- assert(getElemType(A).getTypePtr() == getElemType(B).getTypePtr());
+ // Different element types shouldnt' 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 {
diff --git a/clang/test/AST/ByteCode/c.c b/clang/test/AST/ByteCode/c.c
index 654b3da2b7d66..73469d7fd6cc4 100644
--- a/clang/test/AST/ByteCode/c.c
+++ b/clang/test/AST/ByteCode/c.c
@@ -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}}
+
+
+const int compared2 = strcmp(strcmp, _str); // all-warning {{incompatible
pointer types}} \
+ // all-error {{initializer element
is not a compile-time constant}}
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