sammccall added a comment. In D91258#2392646 <https://reviews.llvm.org/D91258#2392646>, @eugenis wrote:
> Hi Sam, > > this patch is failing on the ubsan bot with: > > [ RUN ] SerializationTest.NoCrashOnBadArraySize > > /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang-tools-extra/clangd/index/Serialization.cpp:90:26: > runtime error: left shift of 127 by 28 places cannot be represented in type > 'int' > #0 0x392dd57 in clang::clangd::(anonymous > namespace)::Reader::consumeVar() > /b/sanitizer-x86_64-linux-fast/build/llvm-project/clang-tools-extra/clangd/index/Serialization.cpp:90:26 Thanks Evgenii! (It's really surprising to me this is using signed arithmetic!) Is the sanitizer strictly correct here that this is UB? From my reading only C requires the result of signed shifts to be representable, not C++. https://eel.is/c++draft/expr.shift So this should be well-defined with the same result as the unsigned arithmetic (assuming 2s complement, I guess). (We'll fix this to use unsigned arithmetic in any case) Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D91258/new/ https://reviews.llvm.org/D91258 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
