[cfe-dev] libclang and plugins

[Stefan Kemnitz]

ok i did something that makes it work, but i don't know whether its a good
way to do it.
It works when the plugin is called from clang and libclang.
I even see my errors appear in vim through YouCompleteMe.

First i added a method loadPlugins() in CompilerInstance that simply does
what it was doing before in ExecuteCompilerInvocation.
In ExecuteCompilerIncovation i removed the loading and called the new
method.
I did the same thing in ASTUnit::Parse.
The problem is, that libclang does not export all the needed symbols that
are needed for plugins to link against it when loaded.
So i added the symbols to tools/libclang/libclang.exports.
Additionally i added a dependency to the plugin so that it links against
libclang.
I think this is not the way it should be done.
What would be a better way to do this ?

https://gist.github.com/realincubus/6cba9934b0d49f539446

Greetings Stefan Kemnitz


2014-09-29 10:57 GMT+02:00 Manuel Klimek <klimek at google.com>:

> On Fri Sep 26 2014 at 8:39:37 PM M.Sc. Stefan Kemnitz <
> kemnitz.stefan at gmail.com> wrote:
>
>> Hi,
>>
>> i am working on a plugin for clang that will show me some custom
>> diagnostics.
>>
>> I extended the "Hello World"-plugin PrintFunctionNames so that it emits
>> an errors if it finds a function declaration ( its just a toy plugin )
>> Everything works fine if i execute it from command line with clang.
>>
>>
>> -------------------------------------------------------------------------------------
>> $ clang -Xclang -load -Xclang <pluginpath>/PrintFunctionNames.so -Xclang
>> -add-plugin -Xclang print-fns main.cpp
>> top-level-decl: "foo"
>> /home/incubus/test/clang-plugins/main.cpp:3:1: error: use of undeclared
>> identifier 'foo'
>> void foo()
>> ^
>> /home/incubus/test/clang-plugins/main.cpp:12:5: error: use of undeclared
>> identifier 'bar'
>>     bar();
>>     ^
>> top-level-decl: "main"
>> /home/incubus/test/clang-plugins/main.cpp:8:1: error: use of undeclared
>> identifier 'main'
>> int main(int argc, char** argv){
>> ^
>> 3 errors generated.
>>
>> ---------------------------------------------------------------------------------------
>>
>> the first and third error are from my plugin and the second is from clang
>> itself.
>>
>> Now i want to do the same thing through libclang.
>> I am using the vim plugin YouCompleteMe to send all of the flags that
>> were passed to clang, to libclang.
>>
>> I followed the path of execution to
>> clang_parseTranslationUnit -> clang_parseTranslationUnit2 ->
>> clang_parseTranslationUnit_impl ->
>>  ASTUnit::LoadFromCommandLine -> ASTUnit::LoadFromCompilerInvocation ->
>> ASTUnit::Parse
>>
>> were the parsing process is started.
>>
>> in FrontendAction::BeginSourceFile  the method
>> FrontendAction::CreateWrappedASTConsumer is called which creates
>> ASTConsumers from the plugins.
>> I found out that the Consumer is not created because the
>> FrontendPluginRegistry does not contain any plugins.
>> This is due to the fact that the plugin was never loaded.
>>
>> I searched the codebase for the loading routines and found out that the
>> only loading is in clang::ExecuteCompilerInvocation.
>> I know that clang_parseTranslationUnit is supposed to Parse the
>> translation unit not to execute the whole compiler.
>>
>> My question is:
>>
>> Is there any way to load the plugin earlier so that it can be executed
>> while parsing?
>> Or if it is not possible. Is there some other way to add custom error
>> messages that will be emitted when running clang_parseTranslationUnit?
>>
>
> I think the right solution is to add a way to load plugins when running
> with libclang.
> I see 2 options:
> 1. add a call to libclang to allow loading of plugins
> + less complexity in the driver
> - libclang tools need to get explicit support for this
> 2. make the driver allow loading clang plugins
> + "just works" with any editor integration
> - more complexity in the driver
>
> I'm leaning towards (2). If you want to give implementing it a try, I'd be
> happy to review patches...
>
> Cheers,
> /Manuel
>
>
>>
>>
>> Greetings Stefan Kemnitz
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>>
>
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