modernize-deprecated-headers¶
Some headers from C library were deprecated in C++ and are no longer welcome in C++ codebases. Some have no effect in C++. For more details refer to the C++ 14 Standard [depr.c.headers] section.
This check replaces C standard library headers with their C++ alternatives and removes redundant ones.
// C++ source file...
#include <assert.h>
#include <stdbool.h>
// becomes
#include <cassert>
// No 'stdbool.h' here.
Important note: the Standard doesn’t guarantee that the C++ headers declare all the same functions in the global namespace. The check in its current form can break the code that uses library symbols from the global namespace.
- <assert.h>
- <complex.h>
- <ctype.h>
- <errno.h>
- <fenv.h> // deprecated since C++11
- <float.h>
- <inttypes.h>
- <limits.h>
- <locale.h>
- <math.h>
- <setjmp.h>
- <signal.h>
- <stdarg.h>
- <stddef.h>
- <stdint.h>
- <stdio.h>
- <stdlib.h>
- <string.h>
- <tgmath.h> // deprecated since C++11
- <time.h>
- <uchar.h> // deprecated since C++11
- <wchar.h>
- <wctype.h>
If the specified standard is older than C++11 the check will only replace headers deprecated before C++11, otherwise – every header that appeared in the previous list.
These headers don’t have effect in C++:
- <iso646.h>
- <stdalign.h>
- <stdbool.h>
The checker ignores include directives within extern “C” { … } blocks, since a library might want to expose some API for C and C++ libraries.
// C++ source file...
extern "C" {
#include <assert.h> // Left intact.
#include <stdbool.h> // Left intact.
}
Options¶
-
CheckHeaderFile
¶
clang-tidy cannot know if the header file included by the currently analyzed C++ source file is not included by any other C source files. Hence, to omit false-positives and wrong fixit-hints, we ignore emitting reports into header files. One can set this option to true if they know that the header files in the project are only used by C++ source file. Default is false.