On 2022/01/24 22:17, Jonathan Matthew wrote: > The proposed update to lang/node makes this irrelevant, but I thought I'd send > it anyway since it may come up elsewhere too. > > I noticed that on one system, 'npm install less' would abort, logging > 'node: backwards memcpy', but on another it worked fine. Eventually I > figured out this was because the working one had packages built with llvm 11, > the other with llvm 13 packages, and llvm 13's memcpy optimiser was turning > a series of small memcpys in node's bundled zlib into one larger one, without > identifying that the src and dest of the larger memcpy could overlap. > > Compiling the bundled zlib with -fno-builtin-memcpy prevents it from doing > that, which fixes npm.
If we can't trust the compiler's builtin memcpy to do the right thing then it probably needs disabling completely...
