[cfe-dev] Missing FieldDecl from macro calls and template arguments

[Adrien Chauve]

On Thu, Jun 16, 2011 at 16:33, Douglas Gregor <dgregor at apple.com> wrote:
>
> On Jun 16, 2011, at 5:14 AM, Adrien Chauve wrote:
>
>> On Wed, Jun 15, 2011 at 23:22, Eli Friedman <eli.friedman at gmail.com> wrote:
>>> On Wed, Jun 15, 2011 at 2:12 PM, Adrien Chauve <adrien.chauve at gmail.com> wrote:
>>>> On Wed, Jun 15, 2011 at 22:13, Eli Friedman <eli.friedman at gmail.com> wrote:
>>>>> On Wed, Jun 15, 2011 at 12:58 PM, Adrien Chauve <adrien.chauve at gmail.com> wrote:
>>>>>> On Wed, Jun 15, 2011 at 21:53, Eli Friedman <eli.friedman at gmail.com> wrote:
>>>>>>> On Wed, Jun 15, 2011 at 12:27 PM, Adrien Chauve <adrien.chauve at gmail.com> wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I've implemented an ASTConsumer deriving from RecursiveASTVisitor to
>>>>>>>> rename field names. The consumer implements VisitFieldDecl and
>>>>>>>> VisitMemberExpr,
>>>>>>>> but it seems that (at least) two kinds of expressions are not visited.
>>>>>>>>
>>>>>>>> 1- First, function arguments that are instance of templates, e.g.:
>>>>>>>>
>>>>>>>>    template<typename T>
>>>>>>>>    struct Foo
>>>>>>>>    {
>>>>>>>>        int bar;
>>>>>>>>
>>>>>>>>        void copy(const Foo<T>& other) {
>>>>>>>>            bar = other.bar;  /// bar is visited but not other.bar
>>>>>>>>        }
>>>>>>>>    };
>>>>>>>
>>>>>>> other.bar in this situation is a CXXDependentScopeMemberExpr, I think...
>>>>>>
>>>>>> Thanks I will definitely try that!
>>>>>>
>>>>>>>>
>>>>>>>> If I write the same code but with a non-template Foo struct, all bar
>>>>>>>> member expressions are visited.
>>>>>>>>
>>>>>>>>
>>>>>>>> 2- Code inside macros, e.g.:
>>>>>>>>
>>>>>>>>    Foo foo;
>>>>>>>>    foo.bar = 2; // bar is visited
>>>>>>>>    assert(foo.bar == 2); // bar is not visited
>>>>>>>>
>>>>>>>> Do I have to get the body of the macro from the Preprocessor and make
>>>>>>>> something with it?
>>>>>>>
>>>>>>> Are you sure you're compiling the given file with asserts enabled?
>>>>>>> The expression won't show up in the AST if it gets #define'ed out.
>>>>>>
>>>>>> I didn't disable asserts with -DNDEBUG, so are they not enabled by default?
>>>>>
>>>>> If you didn't define NDEBUG, they should be enabled... not sure what's
>>>>> going on here.  If the node is getting compiled, it should show up in
>>>>> the AST, though.  Maybe take a look at the output of -ast-dump?
>>>>>
>>>>
>>>> Thanks for the tip! I'm not really familiar with the output of
>>>> ast-dump but it looks really nice and assert is definitely there. I'm
>>>> going to investigate this. Maybe it's because I filtered out the
>>>> expressions based on their locations. If the expression inside an
>>>> assert is located in assert.h, that should answer my question. I
>>>> thought it would be located in the source file where assert is called.
>>>
>>> How exactly are you getting the source location?  There are multiple
>>> locations associated with an expression inside a macro instantiation.
>>>
>>> -Eli
>>>
>>
>> I use:
>>
>>     bool VisitMemberExpr(MemberExpr *Node)
>>     {
>>         SourceLocation loc = Node->getExprLoc();
>>        ...
>>     }
>>
>> By the way, I didn't get the difference between loc and:
>>
>>   instanciated_loc = my_src_manager.getInstatiationLoc(loc);
>
> As noted at
>
>  http://clang.llvm.org/docs/InternalsManual.html#SourceLocation
>
> a source location for a macro instantiation encodes both the spelling location (where the characters came from) and the instantiation location (where the macro was expanded).
>
>  - Doug
>

Thanks! It works now. It was indeed a problem of
getInstanciationLocation/getSpellingLocation.

If I summarize what I understood...

Given a SourceLocation "loc" taken from an expression inside a macro call:

- SourceManager::getInstanciationLoc(loc) gives where the macro was
expanded in the code after the preprocessing step
- SourceManager::getSpellingLocation(loc) gives where the characters
came from in the original source code before expansion (before
preprocessing)

but "loc" itself contains a third location which is different from
instanciation and spelling locations. From my tests, I believe this is
where the macro is defined. Is it?


Thanks,
Adrien