[cfe-dev] clang tool rejects compilation arguments from compilation database (incorrectly?)

[Reid Kleckner]

Clang has basically three command line flag parsing modes:
- the gcc-compatible clang driver, which is the standard command line interface
- the -cc1 command line interface, which is accessible via "clang -cc1
..." and is printed by -###
- the clang-cl command line interface, which is not relevant here

The tooling infrastructure expects your compilation database to
contain flags for the main gcc-style frontend, not the -cc1 subprocess
invocation. So -### won't help you here.

I believe we have some flag that prints the full clang command line
during the compile, but I've forgotten what it is.

On Fri, Oct 24, 2014 at 4:06 AM, Péter Ésik <peter.esik at gmail.com> wrote:
> Hello
>
> I would like to introduce clang tooling to a fairly large code base with a
> custom build system. The first step i wanted to take is to manually create a
> compilation database file for one translation unit, and do some testing on
> that.
>
> First, i added -### to the compilation flags, so i could get the actual
> compiler invocation. I took the ouput, and put it into a
> compile_command.json file. At this point, everything should have worked just
> fine, but it did not. My clang tool for testing is really simple, all it
> does is, it tries to run a clang::SyntaxOnlyAction on the given inputs.
>
> If i try to run my tool on the TU that's in my compilation database, i get
> errors. Here's my compilation database: http://pastebin.com/6gsRHBEN and
> here is my output the tool gives me: http://pastebin.com/4AXfdF0r I also
> tried without the inner-quotes (http://pastebin.com/sWwyvbp8), the result's
> the same.
>
> What really bugs me is that if i open a terminal, switch to the 'directory',
> and copy-paste the content of the 'command' part (without JSON-escaping of
> course), clang compiles the file (and generates the object file) without any
> errors. Also, don't know if relevant, but the project is built using an
> older xcode toolchain (based on clang 3.2), and i built my tool based on
> clang 3.5. Why does my tool reject totally valid arguments, what do i do
> wrong?
>
> Thanks,
> Peter
>
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