Remove dependency on strings.h

[nurupo]

strings.h is not available on MSVC.

---

This change is 

[nurupo]

Looks like the -Werror makes the clang build on Travis fail because clang's ctype.h header triggers -Wdisabled-macro-expansion. gcc and mingw don't have such an issue.

/home/travis/build/TokTok/c-toxcore/testing/misc_tools.c:56:18: error: disabled expansion of recursive macro [-Werror,-Wdisabled-macro-expansion]
        int c1 = tolower(*(s1++));
                 ^
/usr/include/ctype.h:230:35: note: expanded from macro 'tolower'
#  define tolower(c)    __tobody (c, tolower, *__ctype_tolower_loc (), (c))
                                     ^
/usr/include/ctype.h:176:14: note: expanded from macro '__tobody'
            __res = f args;                                                   \
                    ^

@iphydf How should we deal with it, is disabling -Wdisabled-macro-expansion just for clang acceptable?

[Diadlo]

Or we can write own tolower

[cebe]

Review status: 0 of 2 files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

---

testing/misc_tools.c, line 53 at r1 (raw file):

}

int tox_strncasecmp(const char* s1, const char* s2, size_t n)

add a comment that this is implemented because strings.h is not available on MSVC.

---

Comments from Reviewable

[nurupo]

testing/misc_tools.c, line 53 at r1 (raw file):

Previously, cebe (Carsten Brandt) wrote…

add a comment that this is implemented because strings.h is not available on MSVC.

Added.

---

Comments from Reviewable

[Diadlo]

Reviewed 1 of 2 files at r1, 1 of 1 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable

[cebe]

---

Reviewed 1 of 2 files at r1, 1 of 1 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable

[Diadlo]

@cebe Why do you lgtm, if current build is failed?

[cebe]

@Diadlo sorry I did not notice that, was looking at the code only.

[cebe]

---

Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

---

Comments from Reviewable

[Diadlo]

Reviewed 1 of 1 files at r3, 1 of 1 files at r4.
Review status: all files reviewed at latest revision, 1 unresolved discussion.

---

CMakeLists.txt, line 99 at r4 (raw file):

    add_flag("-Wno-covered-switch-default")
    # Due to clang's tolower() macro being recursive https://github.com/TokTok/c-toxcore/pull/481
    add_flag("-Wno-disabled-macro-expansion")

Maybe put inside if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")?

---

Comments from Reviewable

[nurupo]

CMakeLists.txt, line 99 at r4 (raw file):

Previously, Diadlo (Polshakov Dmitry) wrote…

Maybe put inside if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")?

Do we really want this warning to be enabled in the first place?

---

Comments from Reviewable

[iphydf]

could you write a test for this function?

---

Reviewed 1 of 2 files at r1, 1 of 1 files at r3, 1 of 1 files at r4.
Review status: all files reviewed at latest revision, 1 unresolved discussion.

---

Comments from Reviewable

[nurupo]

Uh, sure, if you really want. I thought the function was trivial enough to verify that it does the right thing.

Hm, it's probably easier to just replace this function with an ifdef using strncasecmp() on POSIX systems and _strnicmp() on Windows rather than writing tests for it.

[nurupo]

Added the test. Hopefully the 20 minutes I have spent on it were worth it. Also, I ran out of wafers while writing it, thus the wafer test cases.

[iphydf]

s/mist/mis/

[iphydf]

Thanks, looks good. Can you fix the typo and then rebase? I'll merge it after.

[nurupo]

auto_tests/tox_strncasecmp_test.c, line 164 at r5 (raw file):

Previously, iphydf wrote…

s/mist/mis/

Done.

---

Comments from Reviewable

[iphydf]

Did I merge something after your rebase? I can't merge this, yet. Can you rebase (again)?

[nurupo]

Rebased.