Uwe Rathmann

O.k. now it is understandable, that nobody complained before and I would consider it less urgent than a compiler error. However Qwt headers should not be the reason for warnings when compiling application code and these warnings have to be be avoided - like a couple of deprecation warnings that started to happen with recent Qt versions. Moving the implementation to the cpp file means that there is no inlining anymore. I also dislike this solution because the next Qwt release will drop Qt4.x ( nobody...

After looking a second time to your initial bug report I noticed, that it is "only" about a compiler warning, that is treated as error because you actively enabled -Werror - right ? Could you please build without -Werror and show the line with the warning. Then we can see the specific compiler flag that is responsible for the warning ?

As mentioned before: Qwt is used in so many projects for so long that I can hardly imagine that you are the first one using DLLs with mingw on Windows. So lets have a look how the compiler is used in your build process: 1) How do you build Qwt - using the official qmake project files ? 2) How do you build your application ? 3) What Qt version are you using ? PS: I'm not using Windows myself - actually I do not have a Windows box at all here.

The inline keyword is not used in any of the Qwt class declarations - so the situation you are describing can be found in many Qwt headers. However - it is ike this since 20 years and Qwt has been used in many projects using mingw. So there must be something special about your project ? I had a look at the Qt headers and most of the inlined methods are indeed declared as inline in the class declaration. However you also find something like QSize::QSize, were the inline keyword is for the implementation...

avoid isBarVisible lookups for each sample

using if/else for QwtPlotMultiBarChart::boundingRect

no need to iterate and do lookups to know the number of visible bars

using isBarVisible to improve readability