Clang Flag: -Wmain / -Wno-main

In Clang, the compiler flags -Wmain and -Wno-main are used to control warnings related to the definition and usage of the main function, which is the entry point for C and C++ programs. The -Wmain flag activates additional checks and warnings to ensure the correct usage of the main function according to language standards and best practices. When enabled, it can diagnose issues such as improperly declaring main as variadic, static, or with inappropriate attributes that may lead to undefined behavior or non-standard program behavior. Conversely, -Wno-main suppresses these warnings, allowing for non-standard uses of main without generating compiler diagnostics. This might be useful in certain specialized scenarios or to silence warnings for legacy codebases where changing the definition of main is not feasible. By default, Clang has the -Wno-main behavior active, suppressing warnings related to the use of main. However, for strict compliance with language standards or to ensure best practices in new projects, developers might opt to manually enable the -Wmain flag. Understanding and appropriately using these compiler flags is crucial for developers aiming to maintain high standards of code quality and conformity to language specifications in their projects.

AI Generated

Warnings/Remarks

Default Active (Deactivate with -Wno-main)

ext_noreturn_main	warning: 'main' is not allowed to be declared _Noreturn
ext_variadic_main	warning: 'main' is not allowed to be declared variadic
warn_main_one_arg	warning: only one parameter on 'main' declaration
warn_main_redefined	warning: variable named 'main' with external linkage has undefined behavior
warn_main_returns_bool_literal	warning: bool literal returned from 'main'
warn_static_main	warning: 'main' should not be declared static

Default Inactive (Activate with -Wmain)

ext_main_used

warning: ISO C++ does not allow 'main' to be used by a program