feat(C++): There are lots of compile warnings

[SYaoJun]

Describe the enhancement requested

I conceived two steps to fix those warning.

• Fix current compile warnings gradually fix(c++): fix compile warnings(comparison of int and uint, unused result #849
• Add compile flags(-Werror -Wextra ) to CMakelists.txt feat(cmake): Enable (-Wall -Werror -Wextra) compilation flag to detect potential bugs early  #863

Component(s)

C++

[SYaoJun]