Re: [stable build from source] Ubuntu 20.04 scintilla not found

[John W. Eaton]

On 6/18/20 8:13 AM, JuanPi wrote:

> As far as I understand these libraries are available, e.g.
>
> $ ldconfig -p | grep Qt5Network
>      libQt5Network.so.5 (libc6,x86-64) =>
> /lib/x86_64-linux-gnu/libQt5Network.so.5

I'm kind of surprised that is /lib and not /usr/lib (my Debian system 
has /usr/lib, I didn't know Ubuntu was different).  In any case, do you 
also have

  /lib/x86_64-linux-gnu/libQt5Network.so

I think that's the file the linker expects to find, not the one with the 
version number.  As I understand it, ldconfig is just telling you 
whether the run-time library exists, not whether the library needed for 
linking is present.

If that file is missing, why?  It and the others should be provided by 
the qtbase5-dev (all except for Qt5Help) and qttools5-dev (Qt5Help) 
packages.

If it is present, then why is the linker not finding it?  Also if it is 
present, what is the output of

  ls -l /lib/x86_64-linux-gnu/libQt5Network.so

(or /usr/lib/... if that's where it is)?

The reason this is showing up as a problem with qscintilla and not Qt 
generally is that we check for qscintilla by linking a program.  For the 
Qt libraries, we rely on the result of a pkg-config command.  Maybe we 
should have configure double check by actually attempting to link a 
program instead of just trusting what pkg-config returns.

> but configure is not finding them
>
> $ grep cannot config.log
> /usr/bin/ld: cannot find -lpthreads

The config.log file reports the results of all tests.  Sometimes we 
check several different ways until we find something that works.  So a 
"cannot find" message in the log doesn't necessarily mean that the 
feature is missing.

jwe