Fix #129:

Support of incomplete type in m-shared.

README.md

@@ -4456,6 +4456,12 @@ The object oplist is expected to have at least the following operators (`CLEAR`
 There are designed to work with buffers with policy `BUFFER_PUSH_INIT_POP_MOVE`
 to send a shared pointer across multiple threads.
 
+If the type is an incomplete type, you need to disable the `INIT` operator and not defined the `EMPLACE_TYPE` operator in the given oplist like this:
+
+```C
+  (INIT(0), CLEAR(API_2(incomplete_clear))) )
+```
+
 `SHARED_PTR_DEF_AS` is the same as `SHARED_PTR_DEF` except the name of the type `name_t`
 is provided.
 

m-shared.h

@@ -183,10 +183,12 @@ M_INLINE int m_shar3d_integer_cref(int *p) { return *p; }
   typedef shared_t M_F(name, _ct);                                            \
   typedef type     M_F(name, _subtype_ct);                                    \
                                                                               \
-  typedef struct M_F(name, _combine_s) {                                      \
-    struct M_F(name, _s) ptr;                                                 \
-    type data;                                                                \
-  } M_F(name, combine_ct)[1];                                                 \
+  M_IF(M_OR(M_TEST_METHOD_P(INIT, oplist), M_TEST_METHOD_ALTER_P(EMPLACE_TYPE, oplist)))( \
+    typedef struct M_F(name, _combine_s) {                                      \
+      struct M_F(name, _s) ptr;                                                 \
+      type data;                                                                \
+    } M_F(name, combine_ct)[1];                                                 \
+  , /* nothing to do */ )
 
 /* Define the core functions */
 #define M_SHAR3D_PTR_DEF_CORE(name, type, oplist, cpt_oplist, shared_t)       \

tests/test-mshared.c

@@ -38,6 +38,11 @@ SHARED_PTR_DEF_AS(SharedDouble, SharedDouble, double)
 SHARED_PTR_RELAXED_DEF_AS(SharedDouble2, SharedDouble2, double, M_BASIC_OPLIST)
 SHARED_RESOURCE_DEF_AS(SharedRessource, SharedRessource, SharedRessourceIt, double)
 
+// Test with incomplete structure
+struct incomplete_s;
+extern void incomplete_clear(struct incomplete_s *ptr);
+SHARED_PTR_DEF( shared_incomplete, struct incomplete_s, (INIT(0), CLEAR(API_2(incomplete_clear))) )
+
 static int f(const shared_int_t p)
 {
   return *shared_int_cref(p);