Re: a question on a commit comment

["Johnson, Andrew N. via Core-talk" <core-talk@aps.anl.gov>]

Hi Han,

On 4/3/19 4:15 AM, Jeong Han Lee via Core-talk wrote:

  I am interesting to hear the next sentence after your commit message with the following commit

https://github.com/epics-base/epics-base/commit/2206934ae2c64b5123874117d220480e8b2b1b0a

  "Might be unnecessary, but..."

"... I think it is worth the risk of making these changes to remove another set of warnings from the build."

  We (ESS) has our own ( ^__^ )  issue on this commit. I would like to understand your commit precisely, and do "some patch works" on the latest customized ESS environment.

Interesting, what are your symptoms?

The modification was made to ensure that the $(INSTALL_LIB) directory exists before we link any programs — $(TESTPRODNAME) $(PRODNAME) — or libraries — $(LIBNAME) $(SHRLIBNAME) $(LOADABLE_SHRLIBNAME) — because on macOS the linker flag -L generates a warning if you give it a directory path that doesn't exist. The use of the pipe character '|' in the additional dependency makes that directory target an order-only prerequisite, so it doesn't cause the downstream targets to be rebuilt if the directory's modification date is newer than the target, it just ensures that it exists before running the rule action that does the linking.

The rule change did not happen on the 3.15 branch; when I build the 3.15 libCom tree from scratch on a Mac I get these warnings:

kato$ make -s
ld: warning: directory not found for option '-L/Users/anj/Software/epics/base-3.15/lib/darwin-x86'
ld: warning: directory not found for option '-L/Users/anj/Software/epics/base-3.15/lib/darwin-x86'
ld: warning: directory not found for option '-L/Users/anj/Software/epics/base-3.15/lib/darwin-x86'

They are not displayed when I build the 7.0 branch.

I would like to help you resolve this — I wish sites would work with the core group if they need tweaks to the build system instead of making their own local changes, since that helps us understand your issues and makes us less likely to break your installations in the future. We intend to release Base-7.0 more frequently in the future (Michael wants releases quarterly) so there should be less of a delay between commits and their inclusion in a subsequent release.

- Andrew

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