xref: /llvm-project/clang-tools-extra/docs/clang-tidy/checks/cert/err33-c.rst (revision 543f9e781032f086afa7438065b9ce7a9c07ca2b) 
1.. title:: clang-tidy - cert-err33-c
2
3cert-err33-c
4============
5
6Warns on unused function return values. Many of the standard library functions
7return a value that indicates if the call was successful. Ignoring the returned
8value can cause unexpected behavior if an error has occurred. The following
9functions are checked:
10
11* aligned_alloc()
12* asctime_s()
13* at_quick_exit()
14* atexit()
15* bsearch()
16* bsearch_s()
17* btowc()
18* c16rtomb()
19* c32rtomb()
20* calloc()
21* clock()
22* cnd_broadcast()
23* cnd_init()
24* cnd_signal()
25* cnd_timedwait()
26* cnd_wait()
27* ctime_s()
28* fclose()
29* fflush()
30* fgetc()
31* fgetpos()
32* fgets()
33* fgetwc()
34* fopen()
35* fopen_s()
36* fprintf()
37* fprintf_s()
38* fputc()
39* fputs()
40* fputwc()
41* fputws()
42* fread()
43* freopen()
44* freopen_s()
45* fscanf()
46* fscanf_s()
47* fseek()
48* fsetpos()
49* ftell()
50* fwprintf()
51* fwprintf_s()
52* fwrite()
53* fwscanf()
54* fwscanf_s()
55* getc()
56* getchar()
57* getenv()
58* getenv_s()
59* gets_s()
60* getwc()
61* getwchar()
62* gmtime()
63* gmtime_s()
64* localtime()
65* localtime_s()
66* malloc()
67* mbrtoc16()
68* mbrtoc32()
69* mbsrtowcs()
70* mbsrtowcs_s()
71* mbstowcs()
72* mbstowcs_s()
73* memchr()
74* mktime()
75* mtx_init()
76* mtx_lock()
77* mtx_timedlock()
78* mtx_trylock()
79* mtx_unlock()
80* printf_s()
81* putc()
82* putwc()
83* raise()
84* realloc()
85* remove()
86* rename()
87* setlocale()
88* setvbuf()
89* scanf()
90* scanf_s()
91* signal()
92* snprintf()
93* snprintf_s()
94* sprintf()
95* sprintf_s()
96* sscanf()
97* sscanf_s()
98* strchr()
99* strerror_s()
100* strftime()
101* strpbrk()
102* strrchr()
103* strstr()
104* strtod()
105* strtof()
106* strtoimax()
107* strtok()
108* strtok_s()
109* strtol()
110* strtold()
111* strtoll()
112* strtoumax()
113* strtoul()
114* strtoull()
115* strxfrm()
116* swprintf()
117* swprintf_s()
118* swscanf()
119* swscanf_s()
120* thrd_create()
121* thrd_detach()
122* thrd_join()
123* thrd_sleep()
124* time()
125* timespec_get()
126* tmpfile()
127* tmpfile_s()
128* tmpnam()
129* tmpnam_s()
130* tss_create()
131* tss_get()
132* tss_set()
133* ungetc()
134* ungetwc()
135* vfprintf()
136* vfprintf_s()
137* vfscanf()
138* vfscanf_s()
139* vfwprintf()
140* vfwprintf_s()
141* vfwscanf()
142* vfwscanf_s()
143* vprintf_s()
144* vscanf()
145* vscanf_s()
146* vsnprintf()
147* vsnprintf_s()
148* vsprintf()
149* vsprintf_s()
150* vsscanf()
151* vsscanf_s()
152* vswprintf()
153* vswprintf_s()
154* vswscanf()
155* vswscanf_s()
156* vwprintf_s()
157* vwscanf()
158* vwscanf_s()
159* wcrtomb()
160* wcschr()
161* wcsftime()
162* wcspbrk()
163* wcsrchr()
164* wcsrtombs()
165* wcsrtombs_s()
166* wcsstr()
167* wcstod()
168* wcstof()
169* wcstoimax()
170* wcstok()
171* wcstok_s()
172* wcstol()
173* wcstold()
174* wcstoll()
175* wcstombs()
176* wcstombs_s()
177* wcstoumax()
178* wcstoul()
179* wcstoull()
180* wcsxfrm()
181* wctob()
182* wctrans()
183* wctype()
184* wmemchr()
185* wprintf_s()
186* wscanf()
187* wscanf_s()
188
189This check is an alias of check :doc:`bugprone-unused-return-value <../bugprone/unused-return-value>`
190with a fixed set of functions.
191
192Suppressing issues by casting to ``void`` is enabled by default and can be
193disabled by setting `AllowCastToVoid` option to ``false``.
194
195The check corresponds to a part of CERT C Coding Standard rule `ERR33-C.
196Detect and handle standard library errors
197<https://wiki.sei.cmu.edu/confluence/display/c/ERR33-C.+Detect+and+handle+standard+library+errors>`_.
198The list of checked functions is taken from the rule, with following exception:
199
200* The check can not differentiate if a function is called with ``NULL``
201  argument. Therefore the following functions are not checked:
202  ``mblen``, ``mbrlen``, ``mbrtowc``, ``mbtowc``, ``wctomb``, ``wctomb_s``
203