[cfe-dev] Getting source files into the CompilationDatabase interfaces

[Manuel Klimek]

For anybody interested, I sent out:
http://llvm-reviews.chandlerc.com/D2121

I decided to go for the "optional provided mapping" solution. Thx for all
the feedback / questions / ideas. Feel free to chime in on the review
thread...


On Wed, Nov 6, 2013 at 10:33 AM, Manuel Klimek <klimek at google.com> wrote:

> On Wed, Nov 6, 2013 at 10:03 AM, Aaron Ballman <aaron at aaronballman.com>wrote:
>
>> On Wed, Nov 6, 2013 at 12:59 PM, Manuel Klimek <klimek at google.com> wrote:
>> > On Wed, Nov 6, 2013 at 9:50 AM, Aaron Ballman <aaron at aaronballman.com>
>> > wrote:
>> >>
>> >> On Wed, Nov 6, 2013 at 12:34 PM, Manuel Klimek <klimek at google.com>
>> wrote:
>> >> > Hi,
>> >> >
>> >> > as we've seen more use of the compilation database (for example
>> through
>> >> > the
>> >> > YCM vim plugin), we noticed that for networked build systems and
>> server
>> >> > applications the information we currently expose in the interfaces
>> >> > (path,
>> >> > file-name, command line arguments) is not enough - we also need to be
>> >> > able
>> >> > to get all source code, which we then can put into clang's VFS to
>> get a
>> >> > fully build-system independent clang run over a translation unit.
>> >> >
>> >> > We think that getting the source information (perhaps optionally) as
>> >> > part of
>> >> > a getCompileCommands run is a good fit - a build system always must
>> know
>> >> > how
>> >> > to provide the required sources, and as such it seems to be a natural
>> >> > fit.
>> >>
>> >> I think the premise is sound; it's information that's useful, and
>> >> something the compilation database can definitely provide.
>> >>
>> >> > I'd propose to change the CompilationDatabase interface
>> >> > (tools/clang/include/clang/Tooling/CompilationDatabase.h) to that
>> end,
>> >> > and
>> >> > see two possible solutions, which both have different pros and cons:
>> >> > 1. Add a map from std::string (file-name) -> std::string (source
>> >> > content) to
>> >> > the CompileCommand class (in
>> >> > tools/clang/include/clang/Tooling/CompilationDatabase.h); let
>> specific
>> >> > CompilationDatabases optionally fill in that information
>> >> > 2. Do not modify CompileCommand - instead, add a
>> >> > getCompileCommandsAndSources(StringRef FilePath) method that returns
>> a
>> >> > vector<pair<CompileCommand, map<string, string>>> which also includes
>> >> > the
>> >> > sources; I'm reluctant to split the call into two, as the compile
>> >> > command
>> >> > and the sources are tightly coupled (if a user syncs in the
>> background,
>> >> > both
>> >> > tend to change at the same time)
>> >>
>> >> Can we have a bit more information about these two options?  I think I
>> >> may be a bit confused.  Option #1 sounds like it maps a file name to
>> >> the file contents.  But I can't seem to make heads or tails of what
>> >> the input and outputs are for Option #2.
>> >
>> >
>> > Ah, both basically would additionally provide a map<string, string> that
>> > maps from filenames to file contents, so a client can overlay those file
>> > contents to get a fully hermetic "replay" of the compilation.
>> >
>> > The difference is that option #1 would basically keep the old
>> interface, and
>> > optionally the compilation database could provide the file contents (if
>> it
>> > wants), while option #2 would introduce a new interface for clients to
>> ask
>> > for file contents explicitly if they need it.
>>
>> Option #2 was accepting a file path input, but returning a vector of
>> information -- was the file path the path to the database itself, or
>> to a specific source file?
>>
>
> The source file - we return a vector because we can have multiple ways to
> compile the same file (for example in host and target configuration in
> cross-compilations)
>
>
>>
>> ~Aaron
>>
>
>
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