Jonas Maebe wrote:
On 15 Jul 2011, at 14:40, Mark Morgan Lloyd wrote:
I wonder if I could tack a question onto this. When I started looking at SPARC
Solaris 10 and Solaris 8 earlier in the year, I found that the linker (which I
think was gld) followed symlinks at build time rather than waiting until
runtime. This meant that while I was able to build FPC on 10 without
significant difficulty, I couldn't move the binaries back to 8: I had to
rebuild with a hacked symlink to a temporary copy of one of the standard
libraries (possibly libc, I can't remember for certain).
Is this what one would expect, or is it another ld glitch that might be
platform-specific?
It is expected. The logic is:
a) you build the application using a certain set of headers that go with a
certain version of the library. Hence, the program should be linked against
that particular version of the library
b) you don't want to have to change the build command every time a library gets
updated. Hence, there is a symlink with a generic name going to the default
version of the library (and on most Linux systems this symlink in fact is only
created if you install the -devel version of a package, since it is only
required when compiling programs)
c) if a library changes in a way that breaks backwards compatibility as far as
the api is concerned, its major version is increased so that applications built
against a previous version of the library won't use the newer one and then
crash. Also, since the new version has a different name, you can in principle
have both the old and the new version installed concurrently so that both old
apps and new apps still work (the system however breaks down when a single
program uses e.g. libA and libB that in turn depend on respectively libfoo.1.so
and libfoo.2.so, because both libfoos will probably have a bunch of symbols in
common causing symbol resolution conflicts)
Thanks Jonas, noted and understood. To summarise, a .h corresponds to a
very specific version of a library; if there is a symlink to that
library it is provided as a courtesy.
--
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk
[Opinions above are the author's, not those of his employers or colleagues]
_______________________________________________
fpc-pascal maillist - fpc-pascal@lists.freepascal.org
http://lists.freepascal.org/mailman/listinfo/fpc-pascal
