into an error-only diagnostic in the next Clang release. Fixes
`Issue 50055 <https://github.com/llvm/llvm-project/issues/50055>`_.
+- The ``-Wimplicit-function-declaration`` and ``-Wimplicit-int`` warnings
+ now default to an error in C99, C11, and C17. As of C2x,
+ support for implicit function declarations and implicit int has been removed,
+ and the warning options will have no effect. Specifying ``-Wimplicit-int`` in
+ C89 mode will now issue warnings instead of being a noop.
+
+ **NOTE**: We recommend that projects using configure scripts verify that the
+ results do not change before/after setting
+ ``-Werror=implicit-function-declarations`` or ``-Wimplicit-int`` to avoid
+ incompatibility with Clang 16.
+
- ``-Wincompatible-function-pointer-types`` now defaults to an error in all C
language modes. It may be downgraded to a warning with
``-Wno-error=incompatible-function-pointer-types`` or disabled entirely with