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84a3aadf0f
Reapplication of 7339c0f782d5c70e0928f8991b0c05338a90c84c with a fix for a crash involving arrays without a size expression. Clang supports VLAs in C++ as an extension, but we currently only warn on their use when you pass -Wvla, -Wvla-extension, or -pedantic. However, VLAs as they're expressed in C have been considered by WG21 and rejected, are easy to use accidentally to the surprise of users (e.g., https://ddanilov.me/default-non-standard-features/), and they have potential security implications beyond constant-size arrays (https://wiki.sei.cmu.edu/confluence/display/c/ARR32-C.+Ensure+size+arguments+for+variable+length+arrays+are+in+a+valid+range). C++ users should strongly consider using other functionality such as std::vector instead. This seems like sufficiently compelling evidence to warn users about VLA use by default in C++ modes. This patch enables the -Wvla-extension diagnostic group in C++ language modes by default, and adds the warning group to -Wall in GNU++ language modes. The warning is still opt-in in C language modes, where support for VLAs is somewhat less surprising to users. RFC: https://discourse.llvm.org/t/rfc-diagnosing-use-of-vlas-in-c/73109 Fixes https://github.com/llvm/llvm-project/issues/62836 Differential Revision: https://reviews.llvm.org/D156565
18 lines
620 B
Plaintext
18 lines
620 B
Plaintext
// RUN: %clang_cc1 -triple nvptx64-nvidia-cuda -fcuda-is-device -fsyntax-only -verify -Wno-vla %s
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#include "Inputs/cuda.h"
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// Here we should dump an error about the VLA in device_fn, but we should not
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// print a callstack indicating how device_fn becomes known-emitted, because
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// it's an error to use a VLA in any __device__ function, even one that doesn't
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// get emitted.
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inline __device__ void device_fn(int n);
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inline __device__ void device_fn2() { device_fn(42); }
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__global__ void kernel() { device_fn2(); }
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inline __device__ void device_fn(int n) {
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int vla[n]; // expected-error {{variable-length array}}
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}
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