[cfe-dev] argv[0] in libclang

[Manuel Klimek via cfe-dev]

On Thu, Oct 15, 2015 at 11:02 AM Milian Wolff via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> On Thursday, October 15, 2015 10:30:54 AM CEST Benjamin Kramer via cfe-dev
> wrote:
> > Hi,
> >
> > currently all libclang APIs that get passed a command line expect that
> > there is no argv[0] in the list, i. e. no binary name at the beginning
> > of the command line. We later fake one
> > (clang::createInvocationFromCommandLine) as the invocation gets passed
> > down into the proper clang machinery.
> >
> > This is nasty because it changes the behavior if the original clang
> > invocation would've used a relative path to the standard library:
> >
> > cmdline: /foo/bar/bin/clang -c test.cc
> > std lib in: /foo/bar/include/c++
> > libclang sees: -c test.cc
> >
> > and the stdlib is lost. This comes up if we're using a compile
> > database, for example ycm is using it like this.
> >
> > The only sane solution I see at the moment is to add a new libclang
> > API that expects a full argv. Any other ideas?
>
> In KDevelop, we parse the output of
>
>         clang++ --std=c++11 -xc++ -E -v /dev/null
>
> and pass those in to liblcang as explicit include paths. It works fine for
> our
> use case.


Note that this might also be wrong.
If you have multiple compilers / libstdc++'s installed, it is important to
take the right one for the current project you work in.


> But for a simpler tool it might be far too much overhead of course
> to get up and running. Couldn't the code path in clang use the path to the
> clang library as a fallback when no binary is given? That way, nothing
> needs
> to be changed.
>
> Bye
> --
> Milian Wolff
> mail at milianw.de
> http://milianw.de
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