[cfe-dev] Design proposal: Add custom compilation database formats as plugins

[Douglas Gregor]

On Jul 18, 2012, at 6:36 AM, Daniel Jasper <djasper at google.com> wrote:

> Hi all,
> 
> to make the tooling library more widely applicable, we'd like to make the CompilationDatabase architecture extensible, i.e. provide the option of implementing custom adapters to other kinds of compilation databases (other than the currently available JSONCompilationDatabase).
> 
> In r160061, I provided a hack that enables this, but we definitely want something nicer.
> 
> In the attached patch, I am using LLVM's plugin registry to enable registering new compilation databases. To provide a new CompilationDatabase, you'd need to subclass CompilationDatabasePlugin and CompilationDatabase and register the former with CompilationDatabasePluginRegistry::Add (as shown for JSONCompilationDatabase). This is not a finished patch for review, I'd just like to get feedback on the approach. What do you think?

I definitely prefer this approach!

> Also, several points that need to be addressed:
> - Error handling: In CompilationDatabase::loadFromDirectory, I currently simply try each plugin until I find a compilation database. Any ideas, what I should do with the error messages, especially if I do not find any compilation database. Should I concatenate them, potentially with the plugin-name as a prefix?

Yes, I think it's reasonable to concatenate them with the name of the plug-in, because we don't know which plug-in the user intended to use.

> - Should I move the JSONCompilationDatabase to a separate set of files as it is now loosely coupled?

Sure!

	- Doug