Index template instantiations

[tnicolson]

Hi Anders,

Thanks so much for developing rtags; it's fast becoming indispensible!

Please consider the following code:

#include <iostream>

using namespace std;

struct Thing {
    int x {0};
};

template<typename T>
void g(T& obj) {
    obj.x += 1;
}

int main() {
    auto f = [&](auto& obj) {
        obj.x += 2;
    };

    Thing thing;
    f(thing);
    g(thing);
    cout << thing.x << endl;
}

When requesting references at point on x, rtags currently doesn't find references in functions f or g. How difficult would it be to get rtags to index the template instantiations create when f and g are called?

Thanks,

Tim

[Andersbakken]

Hi Tim

Yeah. It's a bit of a sore point for rtags. I haven't put a lot of time
into trying to figure out how to extract that information from libclang but
I have a suspicion it's not actually available through the public API. I
will try to make another attempt at it however. It's really annoying that
it kinda falls apart inside template functions.

Anders

On Mon, Oct 3, 2016 at 7:04 AM, tnicolson notifications@github.com wrote:

Hi Anders,

Thanks so much for developing rtags; it's fast becoming indispensible!

Please consider the following code:

#include

using namespace std;

struct Thing {
int x {0};
};

template
void g(T& obj) {
obj.x += 1;
}

int main() {
auto f = [&](auto& obj) {
obj.x += 2;
};

Thing thing;
f(thing);
g(thing);
cout << thing.x << endl;

}

When requesting references at point on x, rtags currently doesn't find
references in functions f or g. How difficult would it be to get rtags to
index the template instantiations create when f and g are called?

Thanks,

Tim

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[tnicolson]

Thanks Anders,

Would clang_getSpecializedCursorTemplate help?

Tim

[phcerdan]

I guess this is not easy, I think libclang doesn't expose the full AST for c++, but it would be super good.

[phord]

I ran into this one today, too. But in my case I don't even use the templated typename to get to the information. The fact that the struct is templated seems to induce the failure. Here's my testcase:

#include <vector>
struct foo
{
        int bar;
};

template <bool dummy>
struct temple_struct
{
        std::vector<foo> vec;
        foo foo_inst;
        void fn()
        {
                vec[0].bar = 1;      // 'bar' here is never associated with foo
                foo_inst.bar = 2;
        }
};

struct some_struct
{
        std::vector<foo> vec;
        foo foo_inst;
        void fn()
        {
                vec[0].bar = 3;
                foo_inst.bar = 4;
        }
};

Now if I try to find all uses of "foo::bar" rtags returns three hits:

$ rc -r foo.cpp:4:14
foo.cpp:15:26:	                foo_inst.bar = 2;
foo.cpp:25:24:	                vec[0].bar = 3;
foo.cpp:26:26:	                foo_inst.bar = 4;

It misses only the one in template <bool dummy>temple_struct::std::vector<foo>.