Clang Flag: -Wdeprecated-register / -Wno-deprecated-register

The Clang compiler flags -Wdeprecated-register and -Wno-deprecated-register are used to control warnings related to the use of the register storage class specifier, which has been deprecated in C++17. The register keyword suggests that a variable should be stored in a CPU register for fast access, but modern compilers are much better at optimization, and the use of register is generally no longer recommended. This article focuses on the -Wno-deprecated-register flag, as it is the one active by default. This means that, by default, Clang will issue warnings when the register storage class specifier is encountered in the code, signaling that its use is deprecated and incompatible with C++17 standards. Developers aiming to maintain compatibility with C++17 or later should avoid the use of register, or explicitly suppress these warnings with the -Wno-deprecated-register flag if maintaining older codebases where register is used. Since there are no default inactive elements for -Wdeprecated-register, it implies this flag is not necessary for the suppression of these warnings, as they are already managed by the -Wno-deprecated-register flag. This contributes to cleaner, more modern codebases and assists developers in adopting newer C++ standards by flagging outdated practices.

AI Generated

Supergroups

• -Wc++17-compat (45 elements)
• -Wdeprecated (43 elements)
• -Wregister (2 elements)

Warnings/Remarks

Default Active (Deactivate with -Wno-deprecated-register)

warn_deprecated_register

warning: 'register' storage class specifier is deprecated and incompatible with C++17

Default Inactive (Activate with -Wdeprecated-register)

None