Re: [ft-devel] To Add support for the 'SVG' OpenType table to render color fonts.

[Werner LEMBERG]

>> The best thing is that external library '*librsvg*' is also written
>> mostly in C and exists since 'svg' was standardised.
> 
> Hmm.  As far as I can see, librsvg is moving to Rust as the primary
> source code language...  Fortunately, this is not relevant as long
> as a C API is available that FreeType can use.

Here is a remark one of the MacPorts maintainers sent to the
`macports' e-mail list; it shows that `librsvg' can cause a lot of
headaches...


    Werner


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Rust is a programming language.  The rust port provides a Rust
compiler.  You need a Rust compiler if you want to compile software
written in the Rust language.

Notably, the librsvg port depends on rust.  librsvg is a library for
reading SVG files which has been in MacPorts for a long time, and
dozens of other ports depend on it, including ffmpeg.  Two years ago,
a new developer took over maintenance of the librsvg project and
converted its source code from C to Rust; as a result, you need a Rust
compiler to build librsvg 2.42.0 and later.  The MacPorts librsvg port
was first updated to this new Rust-requiring series on Feb 3, 2018.

Unfortunately, the Rust compiler, like many compilers, is a complex
software project to build, and it was quickly realized that it did not
build on older systems.  On Feb 6, 2018 the librsvg port was modified
to revert to the older pre-Rust 2.40.20 version on OS X 10.7 and
earlier.  On Apr 5, 2018 librsvg was modified to revert to 2.40.20 on
OS X 10.8 as well.  When the rust port is updated to a new version,
this sometimes reveals new problems building on older system, such
that systems which were formerly able to build rust no longer are.
When rust was updated to 1.25.0 on Apr 19, 2018 we found that it no
longer built on OS X 10.9. Therefore, librsvg was modified on May 7,
2018 to use the older 2.40.20 on OS X 10.9 as well.