cmake check if a public field exist in class

Question

// some_library.h
class MyLib {
  public:
  int field_a;
  int field_b; // Only available on some versions
  int field_c; // Only available on some versions
  int ...;
};

A library I'm using have a variable number of public fields depending on versions. In Cmake, is it possible to detect if a certain field from library header exists? (perhaps similar to the CHECK_FUNCTION_EXISTS)

https://cmake.org/cmake/help/latest/module/CheckTypeSize.html — KamilCuk, Jul 22 '20 at 01:09

MatzZze · Accepted Answer · 2020-07-22T17:12:31.920

1

~~You can use check_symbol_exists for a C symbol.~~

Doc: https://cmake.org/cmake/help/latest/module/CheckSymbolExists.html

Or check_cxx_symbol_exists for a CXX symbol.

Doc: https://cmake.org/cmake/help/v3.18/module/CheckCXXSymbolExists.html

You can use check_struct_has_member from CheckStructHasMember. See https://cmake.org/cmake/help/latest/module/CheckStructHasMember.html

CMakeLists.txt

include(CheckStructHasMember)
Check_struct_has_member("class MyLib" field_a ${CMAKE_CURRENT_SOURCE_DIR}/MyLib.h HAS_FIELD_A LANGUAGE CXX)

edited Jul 22 '20 at 17:12

answered Jul 22 '20 at 06:47

MatzZze

391
1
7

How would I express a field name? (I know for function symbol, it's easy). Would `MyLib::field_b` just work? Thanks! – Curious Learner Jul 22 '20 at 16:41
Sorry check_cxx_symbol_exists was wrong for class members. I edited my answer with a tested solution ;) – MatzZze Jul 22 '20 at 17:13
Oh wow! That's neat! That's exactly what I was looking for. Thank you! – Curious Learner Jul 23 '20 at 03:04

cmake check if a public field exist in class

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