Function is removed if it is used from an object defined with auto

[mfornet]

Note function foo in the following code:

Input:

#include <vector>
#include <algorithm>

using namespace std;

class Value
{
public:
    int value;

    Value(int value) : value(value) {}

    int foo() { return value; }
};

int main()
{
    vector<Value> v;

    sort(v.begin(), v.end(), [&](auto &a, auto &b) {
        return a.foo() < b.foo();
    });

    return 0;
}

The expected output is the same code, however, the function foo is removed. Here is the result code:

#include <vector>
#include <algorithm>

using namespace std;

class Value
{
public:
    int value;

};

int main()
{
    vector<Value> v;

    sort(v.begin(), v.end(), [&](auto &a, auto &b) {
        return a.foo() < b.foo();
    });

    return 0;
}

It works ok, if in the comparer, instead of using auto I use [&](Value &a, Value &b) { ... }

[slycelote]

Thanks for the bug report! I could reproduce the issue when an older version of clang library (7.0) is used. With the recent version it works as expected: Value constructor is removed because it's never used; however the function foo is kept. If you build from source, can you try updating the llvm submodule (git submodule update --init) and then passing -DCAIDE_USE_SYSTEM_CLANG=OFF to cmake? If this doesn't help, what are the exact clang options that you provide?

[slycelote]

As for the failure with old clang, this seems to be caused by a clang bug that was fixed in version 8.0.

[mfornet]

Compiling from source is very hard/expensive so I'm using the released binary from caide to use the inliner. I see there is a new release using clang 10.0 so it should work. I'll reopen if that is not the case. Thanks.