1299823 - ld: warning: cannot export hidden symbol _PR_XLock from ../nspr/pr/unix.o

Status: RESOLVED FIXED

(NSPR :: NSPR, defect)

Description

[(not currently active) Ted Mielczarek]

The nss.symbols file has a wildcard export of PR_*:
https://dxr.mozilla.org/mozilla-central/rev/b7f7ae14590aced450bb0b0469dfb38edd2c0ace/config/external/nss/nss.symbols#13

Unfortunately NSPR has a few private symbols that start with PR_, and the linker complains about these on Mac:
04:17:57     INFO -  ld: warning: cannot export hidden symbol _PR_XLock from ../nspr/pr/unix.o
04:17:57     INFO -  ld: warning: cannot export hidden symbol _PR_XUnlock from ../nspr/pr/unix.o
04:17:57     INFO -  ld: warning: cannot export hidden symbol _PR_XIsLocked from ../nspr/pr/unix.o
04:17:57     INFO -  ld: warning: cannot export hidden symbol _PR_XWait from ../nspr/pr/unix.o
04:17:57     INFO -  ld: warning: cannot export hidden symbol _PR_XNotify from ../nspr/pr/unix.o
04:17:57     INFO -  ld: warning: cannot export hidden symbol _PR_XNotifyAll from ../nspr/pr/unix.o

I don't know if we can put an exclusion in the symbols file (probably depends on the syntax of linker scripts and symbol version scripts). Alternately, it's possible we could just remove this code from NSPR, since the only thing that calls it has a comment that mentions code in Mozilla that no longer exists:
https://dxr.mozilla.org/mozilla-central/rev/b7f7ae14590aced450bb0b0469dfb38edd2c0ace/nsprpub/pr/src/md/unix/uxwrap.c#186

Comment 1

[Mike Hommey [:glandium]]

lld turns these warnings into errors.

Comment 2

[Mike Hommey [:glandium]]

Attachment: Bug 1299823 - Rename PR_X* symbols, remove unused ones.

None of these symbols are in a public header, they are not NSPR_API, and
only available on XP_UNIX builds, which in the vast majority of cases,
means built with -fvisibility=hidden (i.e. the symbols are not even
exported in the first place).

The convention for non-exported symbols is to start with _PR rather than
PR, so we rename those symbols.

The PR_XWait, PR_XNotify and PR_XNotifyAll symbols are however never used,
so we just remove them.

Comment 3

[Mike Hommey [:glandium]]

https://hg.mozilla.org/projects/nspr/rev/1938a740809af91496443321b60ca0ab68c4b67b