Fix all warnings & Add option TREAT_WARING_AS_ERROR to cmake

[PragmaTwice]

Done:

• fixed (almost) all warnings (in clang 12):
• add TREAT_WARING_AS_ERROR option:
  • turned ON by default, but OFF in build and test ci (not simple ci) for not blocking merging unexpectedly
  • some error are turned off due to several special reason, including:
    • unused-const-variable unused-private-field unused-variable unused-local-typedef unused-lambda-capture instantiation-after-specialization: disable unused-* for different compile mode (maybe unused in cpu.cmake, but used in cuda.cmake)
    • deprecated-declarations: wait for all deprecated calls are fixed, then it will be removed
    • literal-conversion: wait for oneflow/user/kernels/upsample_kernel.h:141:9: error: implicit conversion from 'double' to 'int' changes value from -0.75 to 0 [-Wliteral-conversion] is fixed, then it will be removed
• add gcc (version 7, 11) and clang (version 12) support
• tested in cuda mode (with gcc)

Notice:

• move operation in return std::move(local_var) is unnecessary because it is guaranteed the returned local variable will be moved in the standard, and the move operation here will prevent a special optimization in compiler called named return value optimization (NRVO).
• move operation in macro CHECK_OK is removed because it will prevent RVO and developer is hard to know a macro which will implicitly do rvalue cast. (parameter type of MaybeIsOK is a rvalue reference, so for a origin rvalue, like f(x), it just works without move, and for an lvalue, a compile error is preferred)

Discovered Problems:

In oneflow/core/job/job_build_and_infer_ctx_mgr.cpp:

 Maybe<void> JobBuildAndInferCtxMgr::OpenJobBuildAndInferCtx(const std::string& job_name) {
-  CHECK_OR_RETURN(!has_cur_job_) << Error::UnknownJobBuildAndInferError
+  CHECK_OR_RETURN(!has_cur_job_) << Error::UnknownJobBuildAndInferError()
                                  << "cur job not leave before you enter this job_name:" << job_name;

In oneflow/user/kernels/upsample_kernel.h:

oneflow/user/kernels/upsample_kernel.h:141:9:
error: implicit conversion from 'double' to 'int' changes value from -0.75 to 0 [-Wliteral-conversion]

[hjchen2]

这里是什么原因需要捕获this的

[PragmaTwice]

不是很清楚，可能之前有用到后来删掉了？不过这个 lambda 应该确实不需要捕获 this

[daquexian]

修改一下 CI，在 .github/workflows/test.yml:137 这些地方加上 -DTREAT_WARNINGS_AS_ERRORS=OFF 吧

[daquexian]

这里 -Wno-deprecated-declarations 现在被换成了 -Wno-error=deprecated-declarations？是不是行为不一样

[PragmaTwice]

是的，-Wno-deprecated-declarations 是不报出 deprecated-declarations 类型的警告，-Wno-error=deprecated-declarations 是报出 deprecated-declarations 类型的警告但不将其视为错误，我感觉这里报出来但不视为错误更合理一些