For given piece of code:
#include <vector>

int main()
{
    std::vector<std::pair<int, int>> a(2);
    a[1].first = 1;
}

KDevelop does not recognize the ".first" expression

Reproducible: Always

Steps to Reproduce:
1. Open a file with the code above in system with C++11 compliant STL.
2. Hover over the "first" word in "a[1].first = 1 line;"

Actual Results:  
No information about the first member is displayed.

Expected Results:  
Kdevelop shows that "first is of int type"

The problem seems related to preprocessor or job scheduling of included files since
kdevelop works correctly when given an output of file preprocessed by g++ i.e.

given the sample code is in file named vector_cpp11.cpp
run the following command:
g++ vector_cpp11.cpp -E -o vector_cpp11_preprocessed.cpp
open the vector_cpp11_preprocessed.cpp file in kdevelop
Kdevelop will correctly show type information for ".first" expression.