Re: [Mingw-cross-env-list] Build / Host / Target

[Mark Brand]

> I think the build / host / target are quite easy to understand:
>
>      "Build" is where the program is compiled.
>      "Host" is where the program will run.
>      "Target" is where the program produces code for.
>
> Thus, "target" makes only sense for compilers and similar stuff.
> In Mingw-cross-env, we have the following situation:
>
>      Normal packages:
>
>          build = Unix
>          host  = Windows
>
>      Native packages (e.g. pkg-config):
>
>          build  = Unix
>          host   = Unix
>
>      GCC, Binutils, NSIS:
>
>          build  = Unix
>          host   = Unix
>          target = Windows


> > > Here is the new and improved version:
> > >
> > > Describe the platform we are building Qt *for* (MinGW aka "win32-g++"):
> > >   -arch  CFG_ARCH
> > >   -xplatform XPLATFORM
> > >   XQMAKESPEC
> > >   -big-endian or -little-endian switch CFG_ENDIAN
> > I would still `think` that -arch and -*-endian are the buidling *on* platform.
> >
> > > Describe the platform we are building Qt *on* (some form of Unix):
> > > -host-arch CFG_HOST_ARCH
> > > -platform PLATFORM
> > > QMAKESPEC
> > > -host-little-endian or -host-big-endian switch CFG_HOST_ENDIAN
> > These definitions of host* seem to contradict Volker's definition.
> > Host can be unix or windows, but arch is always unix.
> I would also think that "-arch" and "-host-arch" should be switched
> in that summary, as well as "-*-endian" and "-host-*-endian". Mark,
> are you sure that your summary is correct?

Well, even "sure" admits of degree and, but I still have confidence in 
my summary. :) Here are two randomly selected pieces of evidence that 
seem strong to me:

1. Consider how the word "host" is used in the warning in the configure 
script about pkg-config when cross-compiling.

2. Consider the endian tests in the configure script at line 5586. 
Notice how the "host" endian tests are coupled with the plain QMAKESPEC 
when the "plain" endian test are coupled with XQMAKESPEC.

Perhaps this fits into your "build / host / target" exposition if we 
consider "host" in the configure script to describe the compiler used to 
build the Qt libraries. The "host" of the compiler is unix and the 
"target" is mingw. The "X" indicates a "target" that is different from 
the "host". As your exposition make clear, the terms "build / host / 
target" describe specific programs, not complex systems like "the Qt 
build system".

This is starting to sound like literary theory, but my conjecture is 
that the "host" and "X" elements appeared later in this history of this 
script as cross-compiling capabilities where added.

regards,

Mark