Produce compiler errors if errno is referenced inside elog/ereport calls. It's often unsafe to reference errno within an elog/ereport call, because there are a lot of sub-functions involved and they might not all preserve errno. (This is why we support the %m format spec: it works off a value of errno captured before we execute any potentially-unsafe functions in the arguments.) Therefore, we have a project policy not to use errno there.
This patch adds a hack to cause an (admittedly obscure) compiler error for such unsafe usages. With the current code, the error will only be seen on Linux, macOS, and FreeBSD, but that should certainly be enough to catch mistakes in the buildfarm if they somehow get missed earlier. In addition, fix some places in src/common/exec.c that trip the error. I think these places are actually all safe, but it's simple enough to avoid the error by capturing errno manually, and doing so is good future-proofing in case these call sites get any more complicated. Thomas Munro (exec.c fixes by me) Discussion: https://postgr.es/m/2975.1526862...@sss.pgh.pa.us Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/a2a8acd15217b1e355c083a41da4dc5c7f35b30b Modified Files -------------- src/common/exec.c | 27 +++++++++++++++++++++------ src/include/utils/elog.h | 21 +++++++++++++++++++++ 2 files changed, 42 insertions(+), 6 deletions(-)