This was originally added for vala only, with the rationale that vala
generates bad code that has warnings. Unfortunately, the rationale was
fatally flawed. The compiler warns about a number of things, which the
user can control depending on their code (or their code generator's
code), but some of those things are absolutely critical to warn about.
In particular, GCC 14 and clang 17 are updating their defaults to warn
-- and error by default for -- invalid C code that breaks the standard,
but has been silently accepted for over 20 years "because lots of people
do it". The code in question is UB, and compilers will generate faulty
machine code that behaves erroneously and probably has a mass of CVEs
waiting to happen.
Compiler warnings are NOT safe to just... universally turn off. Compiler
warnings could be either:
- coding style lints
- threatening statements that the code is factually and behaviorally wrong
There is no magic bullet to ignore the former while respecting the
latter. And the very last thing we should ever do is pass `-w`, since
that causes ALL warnings to be disabled, even the manually added
`-Werror=XXX`.
If vala generated code creates warnings, then the vala compiler can
decrease the log level by generating better code, or by adding warning
suppression pragmas for *specific* issues, such as unused functions.
D lang compilers have an option -release (or similar) which turns off
asserts, contracts, and other runtime type checking. This patch wires
that up to the b_ndebug flag.
Fixes#7082
Explicitly warn with the `#warning` macro to ensure that ICC emits
a warning since ICC does not emit a warning for unused variables.
Also makes the test more reliable with other compilers.
Benjamin Gilbert
Jussi Pakkanen
Eli Schwartz
Daniel Mensinger
Eli Schwartz
Jon Turney
Dylan Baker
Nicolas Schneider
Nirbheek Chauhan