I can give that a go: but I'd be very surprised. I'm no expert (clearly!) but I can't see how a null-pointer check could be involved anywhere here. Even if a pointer check was erased, I can't see how "callq 0" could ever be valid: the linker seemingly just has left the stub "callq 0" in from the (non-LTO) .o file. I will test with -fno-delete-null-pointer-checks though. On Thu, Mar 17, 2016 at 12:03 PM, Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx> wrote: > On 2016.03.17 at 11:50 -0500, Matt Godbolt wrote: >> Hi, >> >> I confirmed we're passing -std=c++1y in both cases (yes; this has >> bitten us before so we're sensitive to this! :). That said; I believe >> the list ABI change was guarded with new namespaces (as was the >> std::string changes that came alongside). >> >> There's no ODR violations that we can find. We build with -Wall >> -Wextra -Werror and have seen ODR errors reported during LTO before, >> but do not have any in this project. We run (a debug version) with >> -fsanitize=undefined (or at least a subset of undefined behaviour), >> and that's clean. The subset does not include "taking reference to a >> null pointer" as this is something parts of our code do. (None >> involving std::function or any lists). > > Hmm, this sounds like -fno-delete-null-pointer-checks may help. > > -- > Markus -- Matt
