Convert IES to C++

[dafeda]

Issue
Resolves #2310

Approach
I wrapped all function in ies_enkf.cpp in extern C to make dlsym work.
Is there a better way?

Other than that, I had to do a few ´static_casts`.

[pinkwah]

Did you get an error when you didn't have extern "C"? Iirc, we use dlsym to find the EXTERNAL_MODULE_SYMBOL symbol, not any of the functions.

[dafeda]

Did you get an error when you didn't have extern "C"? Iirc, we use dlsym to find the EXTERNAL_MODULE_SYMBOL symbol, not any of the functions.

Here's the error I get without extern C:

Consolidate compiler generated dependencies of target ies_std_compare
[ 63%] Building CXX object lib/CMakeFiles/ies_std_compare.dir/analysis/modules/tests/ies_std_compare.cpp.o
[ 64%] Linking CXX executable ies_std_compare
Undefined symbols for architecture x86_64:
  "_ies_enkf_init_update", referenced from:
      cmp_std_ies(res::es_testdata const&) in ies_std_compare.cpp.o
  "_ies_enkf_updateA", referenced from:
      cmp_std_ies(res::es_testdata const&) in ies_std_compare.cpp.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [lib/ies_std_compare] Error 1
make[1]: *** [lib/CMakeFiles/ies_std_compare.dir/all] Error 2
make: *** [all] Error 2

My understanding is that we load ies using dlsym but this won't work if the functions are not wrapped in extern C because of C++'s name-mangling.

[pinkwah]

You wouldn't be getting linking errors if this was a dlsym, as that is a dynamic lookup at runtime.

This particular error occurs because the function is declared with extern "C" in the header file:

ert/libres/lib/analysis/modules/ies_enkf.h

Lines 28 to 36 in 691316d

	#ifdef __cplusplus
	extern "C" {
	#endif
	void ies_enkf_init_update(void *arg, const bool_vector_type *ens_mask,
	const bool_vector_type *obs_mask,
	const matrix_type *S, const matrix_type *R,
	const matrix_type *dObs, const matrix_type *E,
	const matrix_type *D, rng_type *rng);

[pinkwah]

Otherwise this PR looks good.

[dafeda]

You wouldn't be getting linking errors if this was a dlsym, as that is a dynamic lookup at runtime.

This particular error occurs because the function is declared with extern "C" in the header file:

ert/libres/lib/analysis/modules/ies_enkf.h

Lines 28 to 36 in 691316d

	#ifdef __cplusplus
	extern "C" {
	#endif
	void ies_enkf_init_update(void *arg, const bool_vector_type *ens_mask,
	const bool_vector_type *obs_mask,
	const matrix_type *S, const matrix_type *R,
	const matrix_type *dObs, const matrix_type *E,
	const matrix_type *D, rng_type *rng);

I tried removing extern C from ies_enkf.hpp and reverted the change in ies_enkf.cpp, see last commit.
I'm now getting the same error as before.
It's still a linker error where the test ies_std_compare.cpp can't find symbols.

[ManInFez]

typo in comment

[ManInFez]

Why are these changing place?

[dafeda]

Because the C++ compiler complains that they are not in the same order as defined in analysis_table.hpp.
C-compiler did not care.