njlr

CXX	Templates	Templates with Forward Decls
clang 4.0	30s	12s compile + 16s link
g++ 6.2	48s	14s compile + 12s link

njlr

// ...
// Vector class above

// Forward declaration of common sizes
extern template class Vector<16>;
extern template class Vector<32>;
extern template class Vector<64>;
extern template class Vector<128>;

njlr

#include <vector.hpp>

// Instantiation of common sizes
template class Vector<16>;
template class Vector<32>;
template class Vector<64>;
template class Vector<128>;

njlr

// Vector<16> is in another binary
extern template class Vector<16>;

njlr

CXX	Macros	Preprocessed Macros	Templates
clang 4.0	40s	37s	30s
g++ 6.2	61s	66s	48s

njlr

#define CREATE_VECTOR(D) \
struct Vector_##D {\
  static constexpr int N = D;\
  int data[N];\
\
  Vector_##D (Vector_##D const& v) {\
    for(int i=0; i<N ; ++i) {\
      data[i] = v[i];\
    }\
  }\

njlr

template<int D>
struct Vector {
  static constexpr unsigned N = D;
  int data[N];
  
  Vector(Vector<D> const& v) {
    for (int i = 0; i < N; ++i) {
      data[i] = v[i];
    }
  }

njlr

// Create a vector of 10 elements, all initialized to 0
auto v = Vector<10>(0);

// Set the 1st element to 7
v[0] = 7;

// Set the 9th element to 3
v[8] = 3;

// Print the sum of all elements

njlr

import com.google.common.base.Charsets;
import com.google.common.io.MoreFiles;
import com.google.common.io.ByteSink;
import java.nio.file.Path;

public final class GuavaFileUtils {

    private GuavaFileUtils() {
    
    }

njlr

constexpr unsigned fibonacci(const unsigned x) {
  return x <= 1 ? 
    1 : 
    fibonacci(x - 1) + fibonacci(x - 2);
}

int main() {
  return fibonacci(5);
}