Quoting Nicolai Hähnle (2017-10-17 13:40:00) > On 17.10.2017 22:33, Dylan Baker wrote: > > Quoting Nicolai Hähnle (2017-10-17 13:05:12) > >> On 17.10.2017 21:21, Dylan Baker wrote: > >>> +<dt><code>CC, CFLAGS, CXX, CXXFLAGS</code></dt> > >>> +<dd><p>These environment variables > >>> +control the C and C++ compilers used during the build. The default > >>> compilers > >>> +depends on your operating system. Meson supports GCC, Clang, and MSVC as > >>> first > >>> +class compilers. There is some support for the Intel ICC compiler. No > >>> other > >>> +C/C++ compilers are currently supported. > >>> +</dd> > >>> + > >>> +<dt><code>PKG_CONFIG_PATH</code></dt> > >>> +<dd><p>The > >>> +<code>pkg-config</code> utility is a hard requirement for configuring and > >>> +building mesa. It is used to search for external libraries > >>> +on the system. This environment variable is used to control the search > >>> +path for <code>pkg-config</code>. For instance, setting > >>> +<code>PKG_CONFIG_PATH=/usr/X11R6/lib/pkgconfig</code> will search for > >>> +package metadata in <code>/usr/X11R6</code> before the standard > >>> +directories.</p> > >>> +</dd> > >>> +</dl> > >> > >> Not knowing Meson, how do environment variables like CFLAGS, CC, etc. > >> work? Are they "latched" when calling `meson $builddir`? When calling > >> `meson configure`? Both? Does setting them have an effect when calling > >> `ninja`? > > > > I'll update this document as well, but for your edification: they are > > "latched" > > by meson and stored in it's configuration information, they can be > > overwritten > > when meson is initialized or re-initialized. That means that passing them to > > "meson configure" won't change anything, since meson configure just touches > > stored variables, but doesn't re-initialize. Passing them to ninja will > > only do > > something if ninja decides that it needs to re-initialize, say if you touch > > a > > meson.build file. > > Thanks! > > > > examples: > > CC=clang CXX=clang++ meson build-clang > > CC=notacompiler CXX=notacompiler ninja -C build > > will result in building with clang/clang++ > > > > touch meson.build > > CC=notacompiler CXX=notacompiler ninja -C build > > nothing works, since ninja will re-initialize meson and it will read the > > environment and set the compiler to notacompiler and fail. > > :( > > Presumably at least it doesn't break if CC and CXX are unset? In the > sense that the old values are kept?
Yes, if any of these are unset on subsequent re-initializations the previous
value is retained.
so:
CC=clang CXX=clang++ meson build-clang
CC=notacompiler CXX=notacompiler ninja -C build-clang clean
touch meson.build
ninja -C build-clang
Would build with clang, clean, and build with clang again.
Dylan
>
> Cheers,
> Nicolai
>
>
> >
> > I'll also add this to the documentation, but meson remembers options, and
> > meson
> > configure only changes options that you supply so:
> > meson build --prefix=/tmp
> > meson configure build -Ddri-drivers=i965
> > will not reset the prefix.
> >
> > Dylan
> >
>
>
> --
> Lerne, wie die Welt wirklich ist,
> Aber vergiss niemals, wie sie sein sollte.
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