interesting thread about whether it's OK to create dialects of C and C++ that zero-initialize local variables
lists.llvm.org/pipermail/cfe-
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my view is that the current non-initializing behavior is so clearly bad that we should allow this dialect to develop and worry about standardizing it later
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It's undefined behavior and defining it as zero is no more of a language dialect than guaranteeing a non-zero pattern or guaranteeing that it traps. Traps are something that can be relied upon and processed. It's no more of a language extension than any of the UBSan sanitizers.
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I disagree: it's a real dialect once people start depending on it in production.
it's a good dialect, but it's a dialect in practice even if you can use an UB-related argument to claim that it isn't.
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Code does depend on reading uninitialized data in production. The dialect of C and C++ being broadly used including to write LLVM has uninitialized variable accesses. In general, it's incorrect to compile many projects including LLVM without -ftrivial-auto-var-init=zero.
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The language leaves it up to compilers to choose how to implement implementation-defined and undefined behavior. LLVM historically didn't provide a way to get safe implementations of most undefined behaviors but -fsanitize=undefined -fsanitize-trap=undefined is exactly that.
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How is that not a dialect? This code will work on compilers that implement zero-init and will likely fail randomly or have vulnerabilities on compilers that don't.
Perhaps we don't have a common understanding of what a dialect is.
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