Resolves
https://github.com/llvm/llvm-project/issues/76208#issuecomment-2830854351
Quoting the docs of `[[clang::flag_enum]]`:
https://clang.llvm.org/docs/AttributeReference.html#flag-enum
> This attribute can be added to an enumerator to signal to the compiler that it
> is intended to be used as a flag type. This will cause the compiler to assume
> that the range of the type includes all of the values that you can get by
> manipulating bits of the enumerator when issuing warnings.
Ideally, we should still check the upper bounds but for simplicity let's not bother for now.
The checker EnumCastOutOfRange verifies the (helpful, but not
standard-mandated) design rule that integer to enum casts should not
produce values that don't have a corresponding enumerator. As it was
improved and cleaned up by recent changes, this commit renames it from
`alpha.cplusplus.EnumCastOutOfRange` to `optin.core.EnumCastOutOfRange`
to reflect that it's no longer alpha quality.
As this checker handles a basic language feature (which is also present
in plain C), I moved it to a "core" subpackage within "optin".
In addition to the renaming, this commit cleans up the documentation in
`checkers.rst` and adds the new example code to a test file to ensure
that it's indeed producing the behavior claimend in the documentation.
EnumCastOutOfRange checker now reports the name of the enum in the
warning message. Additionally, a note-tag is placed to highlight the
location of the declaration.
A significant number of our tests in C accidentally use functions
without prototypes. This patch converts the function signatures to have
a prototype for the situations where the test is not specific to K&R C
declarations. e.g.,
void func();
becomes
void func(void);
This is the eighth batch of tests being updated (there are a
significant number of other tests left to be updated).
Summary: EnumCastOutOfRangeChecker should not perform enum range checks on LValueToRValue casts, since this type of cast does not actually change the underlying type. Performing the unnecessary check actually triggered an assertion failure deeper in EnumCastOutOfRange for certain input (which is captured in the accompanying test code).
Reviewers: #clang, Szelethus, gamesh411, NoQ
Reviewed By: Szelethus, gamesh411, NoQ
Subscribers: NoQ, gamesh411, xazax.hun, baloghadamsoftware, szepet, a.sidorin, mikhail.ramalho, donat.nagy, dkrupp, Charusso, bjope, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D66014
llvm-svn: 369760
