https://github.com/osamakader created https://github.com/llvm/llvm-project/pull/160015
This fixes issue #153948 where clang crashes with assertion failure 'Array of unknown size' when evaluating strlen() on external const char[] declarations. The issue was in evaluateStrlen() which called getNumElems() on unknown size arrays, leading to an assertion in Descriptor::getSize(). Fix: Add check for isUnknownSizeArray() before calling getNumElems() to gracefully handle unknown size arrays by returning false (indicating strlen cannot be evaluated at compile time). Tested with the reproducer from the GitHub issue. >From 8eb98a93cc912887c302def9b8259688df64cfdc Mon Sep 17 00:00:00 2001 From: Osama Abdelkader <[email protected]> Date: Mon, 22 Sep 2025 00:59:48 +0300 Subject: [PATCH] [clang][bytecode] Fix unknown size arrays crash in clang bytecode This fixes issue #153948 where clang crashes with assertion failure 'Array of unknown size' when evaluating strlen() on external const char[] declarations. The issue was in evaluateStrlen() which called getNumElems() on unknown size arrays, leading to an assertion in Descriptor::getSize(). Fix: Add check for isUnknownSizeArray() before calling getNumElems() to gracefully handle unknown size arrays by returning false (indicating strlen cannot be evaluated at compile time). Tested with the reproducer from the GitHub issue. --- clang/lib/AST/ByteCode/Context.cpp | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp index cfda6e8ded760..f9bc3906beec1 100644 --- a/clang/lib/AST/ByteCode/Context.cpp +++ b/clang/lib/AST/ByteCode/Context.cpp @@ -245,6 +245,11 @@ bool Context::evaluateStrlen(State &Parent, const Expr *E, uint64_t &Result) { if (!FieldDesc->isPrimitiveArray()) return false; + // Handle unknown size arrays - we can't determine the length at compile time + if (Ptr.isUnknownSizeArray()) { + return false; + } + unsigned N = Ptr.getNumElems(); if (Ptr.elemSize() == 1) { Result = strnlen(reinterpret_cast<const char *>(Ptr.getRawAddress()), N); _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
