Please test: changes in how Qt4 is found

Thiago Macieira thiago at
Fri Apr 28 22:57:11 BST 2006

William A. Hoffman wrote:
>>But we do recommend using pkg-config for finding Qt/X11. Not qmake.
>> qmake is a separate program that doesn't have to be installed to use
>> or develop with Qt.
>That is a surprise.    I thought that qt used qmake as part of its own
>build process, and put qmake into the bin directory when qt was
> installed.

It does.

But Qt doesn't have to find Qt in order to build Qt. So we don't have to 
run pkg-config. The support is there, though.

>>Most of our Windows-only users don't care about qmake. They use
>>Microsoft's tools and that's it. At most, they use the Visual Studio
>>integration and generate the project files with qmake, then stop using
>Cross platform (Windows/Linux projects) most likely depend on qmake to
>get things right.   So, what about Windows/Linux users?

They either use qmake themselves, or their own buildsystems (which means 
they don't use qmake).

Cmake is the only buildsystem that depends on another buildsystem being 
installed (qmake) for it to work. What the FindQt4.cmake script is doing 
is akin to creating a file and running "autoconf && 

>>Use pkg-config to find qmake? Why? If pkg-config is found, ask it where
>>QtCore is, what its CXXFLAGS are, what the rpath flags are, where moc,
>>uic, etc. are.
>So, if someone builds qt, then puts that qt bin their PATH, but does
>not set the pkg-config environment variable, they will get the wrong
>qt if there are two on the system.  Can pkg-config handle more than
>one build of QT?

No, it won't be the wrong one. By definition, it will be the right one. 
Trolltech recommends using pkg-config, so what pkg-config finds is the 
correct one.

And, yes, pkg-config can handle more than one prefix. Just set 
PKG_CONFIG_PATH to the one you want.

Thiago Macieira  -  thiago (AT) - thiago (AT)
  thiago.macieira (AT)     Trolltech AS
    GPG: 0x6EF45358                   |  Sandakerveien 116,
    E067 918B B660 DBD1 105C          |  NO-0402
    966C 33F5 F005 6EF4 5358          |  Oslo, Norway
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