Fix explicit link warning - doxygen

Question

I have rather big project with doxygen and some files marked as #internal, some not.
When I build internal documentation no warnings are generated, but when I try to build not internal I got some warnings:
some_header.h:61 warning: explicit link request to 'MyStruct' could not be resolved
some_header.h:58 warning: explicit link request to 'AnotherMyStruct' could not be resolved
some_header.h:58 warning: explicit link request to 'AnotherMyStruct' could not be resolved
some_header.h:61 warning: explicit link request to 'MyStruct' could not be resolved
But some_header.h is internal. As an idea I think that it is included in non internal file, but it is wrong. I deleted all includes of the header, but the message doesn't gone.
How can I fix this warning?
P.S. duplicates of warning mean that there 2 places with error?
$doxygen -x
FULL_PATH_NAMES = NO
JAVADOC_AUTOBRIEF = YES
OPTIMIZE_OUTPUT_FOR_C = YES
EXTRACT_STATIC = YES
QUIET = YES
WARN_IF_UNDOCUMENTED = NO
WARN_FORMAT =
FILE_PATTERNS = *.c *.h
RECURSIVE = YES
EXAMPLE_PATTERNS =
SOURCE_BROWSER = YES
REFERENCED_BY_RELATION = YES
REFERENCES_RELATION = YES
ALPHABETICAL_INDEX = NO
HTML_OUTPUT =
SEARCHENGINE = NO
GENERATE_LATEX = NO
LATEX_OUTPUT =
PDF_HYPERLINKS = NO
USE_PDFLATEX = NO
RTF_OUTPUT =
MAN_LINKS = YES
MACRO_EXPANSION = YES
EXPAND_ONLY_PREDEF = YES
PREDEFINED = (a lot of)
TEMPLATE_RELATIONS = YES
Simple example to reproduce problem:
flags.h:
/**
* #file
* #brief Public Flags.
*/
#ifndef PUBLIC_FLAGS_H
#define PUBLIC_FLAGS_H
#pragma once
/**
* Public flags
*/
typedef enum {
FLAG_READ = 1, /**< reading allowed */
FLAG_WRITE = 2, /**< writing allowed */
} PublicFlags;
#endif /* PUBLIC_FLAGS_H */
info.h
/**
* #file
* #brief Public header.
*/
#ifndef TEST_PUBLIC_H
#define TEST_PUBLIC_H
#pragma once
#include "flags.h"
/**
* Defines public enum.
*/
typedef enum EPublicEnum {
TestEnum1, /**< enum 1 */
TestEnum2, /**< enum 2 */
TestEnum3 /**< enum 3 */
} PublicEnum;
/**
* Defines public struct.
*/
typedef struct SPublicStruct {
PublicEnum state; /**< state (see #PublicEnum). */
unsigned flags; /**< set of flags see #PublicFlags.*/
} PublicStruct;
#endif /* TEST_PUBLIC_H */
internal_enums.h
/**
* #internal
* #file
* #brief Internal Enums
*/
#ifndef INTERNAL_ENUMS_H
#define INTERNAL_ENUMS_H
#pragma once
#include "flags.h"
#include "info.h"
/**
* Possible types:
*
* TypeMisc - Misc type.
* TypeIo - IO type.
*/
typedef enum {
TypeMisc,
TypeIo,
} InternalEnumType;
/** Owner type. */
typedef enum {
Kernel = 0, /**< kernel. */
User = 1 /**< user. */
} InternalEnumOwner;
#endif /* INTERNAL_ENUMS_H */
internal_struct.h
/**
* #internal
* #file
* #brief Internal structures.
*/
#ifndef INTERNAL_STRUCT_H
#define INTERNAL_STRUCT_H
#include "internal_enums.h"
typedef struct SInternalStruct {
rtl_uint8_t owner : 1; /**< values from #InternalEnumOwner */
rtl_uint8_t type : 1; /**< values from #InternalEnumType */
} InternalStruct;
#endif /* INTERNAL_STRUCT_H */
problem:
warning: explicit link request to 'InternalEnumOwner' could not be resolved
warning: explicit link request to 'InternalEnumType' could not be resolved

Answer 1

There is a misunderstanding about what the \internal command does in doxygen does, from the documentation:
24.29 \internal
This command starts a documentation fragment that is meant for internal use only. The fragment naturally ends
at the end of the comment block. You can also force the internal section to end earlier by using the \endinternal
command.
If the \internal command is put inside a section (see for example \section) all subsections after the command
are considered to be internal as well. Only a new section at the same level will end the fragment that is considered
internal.
You can use INTERNAL_DOCS in the configuration file to show (YES) or hide (NO) the internal documentation.
This means that the comment between the \internal and the \endinternal (or end of the comment block) is not part of the documentation (unless the setting INTERNAL_DOCS is set), in this case it is just about the parts like:
/**
* #internal
* #file
* #brief Internal structures.
*/
so the \internal command here has not the desired effect and should be removed.
What actually is desired (when I understand it correctly) is that the entire file isn't used. This can be accomplished by means of either:
add the setting EXCLUDE_PATTERNS = internal*
or
explicitly listing all files and directories that should be used, her this is by adding the setting INPUT = info.h flags.h
In case only part of a file, i.e documentation and code, should not enter the documentation one can use the commands \cond ... \endcond. For disabling just part of a documentation block the commands \if .. \endif are useful. Both sets of commands go together with the setting ENABLED_SECTIONS.
For a description of the mentioned command see the doxygen manual (e.g. at https://www.doxygen.nl/manual/index.html and more specifically the chapters: https://www.doxygen.nl/manual/config.html and https://www.doxygen.nl/manual/commands.html)