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

[Manuel Klimek]

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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