unknown type name error with typedef struct and extern declaration - C language

Question

I would like to understand an error from my compiler in C language.

In a file application.h, I create a typedef struct :

typedef struct
{
    FLOAT64 CoefficientA1_F64;
    FLOAT64 CoefficientA2_F64;
    FLOAT64 CoefficientB0_F64;
    FLOAT64 CoefficientB1_F64;
    FLOAT64 CoefficientB2_F64;
    FLOAT32 OldOldRawValue_F32;
    FLOAT32 OldRawValue_F32;
    FLOAT32 RawValue_F32;
    FLOAT32 OldOldFilteredValue_F32;
    FLOAT32 OldFilteredValue_F32;
    FLOAT32 FilteredValue_F32;
}ButterwothSecondOrderFilterParameter_str;

Then I create variable in another file temperature.c :

ButterwothSecondOrderFilterParameter_str TMP_TemperatureLowPassFilterParameter_STR;

Then I declare this new variable as extern in temperature.h to do the possibility to use it in another file :

extern ButterwothSecondOrderFilterParameter_str TMP_TemperatureLowPassFilterParameter_STR;

For a *.c file I only includes his related *.h file and if I need global variable from another *.h file I include it in the *.h file

For example temperature.c only includes temperature.h and to access to the typedef struct of application.h I include application.h in temperature.h.

For my *.h file I always encapsulate with a :

#ifndef xxxx
#define xxxx
#endif

And this is this last declaration which generates an error :

Description Resource    Path    Location    Type
unknown type name 'ButterwothSecondOrderFilterParameter_str'

I don't know where's my error.... ?

Answer 1

Justly I included application.h in temperature.h. Then temperature.h is the only file included in temperature.c. I add that temperature.h is included in application.h too normally without consequence.

I tried to add application.h directly in temperature.c but I have the same error.

I tried to delete the extern declaration in temperature.h and it works.

So the type in unknown for temperature.h but not for temperature.c....I don't understand.