1.. title:: clang-tidy - bugprone-suspicious-string-compare
2
3bugprone-suspicious-string-compare
4==================================
5
6Find suspicious usage of runtime string comparison functions.
7This check is valid in C and C++.
8
9Checks for calls with implicit comparator and proposed to explicitly add it.
10
11.. code-block:: c++
12
13    if (strcmp(...))       // Implicitly compare to zero
14    if (!strcmp(...))      // Won't warn
15    if (strcmp(...) != 0)  // Won't warn
16
17Checks that compare function results (i,e, ``strcmp``) are compared to valid
18constant. The resulting value is
19
20.. code::
21
22    <  0    when lower than,
23    >  0    when greater than,
24    == 0    when equals.
25
26A common mistake is to compare the result to `1` or `-1`.
27
28.. code-block:: c++
29
30    if (strcmp(...) == -1)  // Incorrect usage of the returned value.
31
32Additionally, the check warns if the results value is implicitly cast to a
33*suspicious* non-integer type. It's happening when the returned value is used in
34a wrong context.
35
36.. code-block:: c++
37
38    if (strcmp(...) < 0.)  // Incorrect usage of the returned value.
39
40Options
41-------
42
43.. option:: WarnOnImplicitComparison
44
45   When non-zero, the check will warn on implicit comparison. `1` by default.
46
47.. option:: WarnOnLogicalNotComparison
48
49   When non-zero, the check will warn on logical not comparison. `0` by default.
50
51.. option:: StringCompareLikeFunctions
52
53   A string specifying the comma-separated names of the extra string comparison
54   functions. Default is an empty string.
55   The check will detect the following string comparison functions:
56   `__builtin_memcmp`, `__builtin_strcasecmp`, `__builtin_strcmp`,
57   `__builtin_strncasecmp`, `__builtin_strncmp`, `_mbscmp`, `_mbscmp_l`,
58   `_mbsicmp`, `_mbsicmp_l`, `_mbsnbcmp`, `_mbsnbcmp_l`, `_mbsnbicmp`,
59   `_mbsnbicmp_l`, `_mbsncmp`, `_mbsncmp_l`, `_mbsnicmp`, `_mbsnicmp_l`,
60   `_memicmp`, `_memicmp_l`, `_stricmp`, `_stricmp_l`, `_strnicmp`,
61   `_strnicmp_l`, `_wcsicmp`, `_wcsicmp_l`, `_wcsnicmp`, `_wcsnicmp_l`,
62   `lstrcmp`, `lstrcmpi`, `memcmp`, `memicmp`, `strcasecmp`, `strcmp`,
63   `strcmpi`, `stricmp`, `strncasecmp`, `strncmp`, `strnicmp`, `wcscasecmp`,
64   `wcscmp`, `wcsicmp`, `wcsncmp`, `wcsnicmp`, `wmemcmp`.
65