In our project, we have defined a macro to force function inlining using __attribute__((always_inline)), which is a fairly common practice — I’ve seen many projects use this technique.
The issue is that when Ceedling/CMock encounters a macro preceding a function declaration, it generates invalid mock files with invalid syntax.

temp2.h:

#define INLINE inline
int a; // Another bug: without this dummy line, Ceedling does not generate any mocking for bar()

INLINE int bar(void) // Ceedling fails mocking this function
{
    return 10;
}

mock_temp2.h:

I tried to change this setting in project.yml from:

:cmock:
  :strippables:  ['(?:__attribute__\s*\([ (]*.*?[ )]*\)+)']

into (added |(INLINE)):

:cmock:
  :strippables:  ['(?:__attribute__\s*\([ (]*.*?[ )]*\)+)|(INLINE)']

However, in this case, a different issue arises: the linker complains that bar() is defined multiple times — once in temp2.h and once in mock_temp2.c

Example project:
ceedling_test.zip