hokein added a comment.
> That looks remarkably like google benchmark main loop. (i don't know at hand
> if making this const will break it, but probably not?)
> I wonder if instead there should be an option to not complain about the
> variables that aren't actually used?
Yeah, it is google benchmark library.
The new fix `for (const auto& _ : state)` will trigger -Wunused warning.
`__attribute__((unused))` doesn't help to suppress the warning :(
$ cat /tmp/main4.cc
#include <vector>
struct __attribute__((unused)) Foo {
};
void f() {
std::vector<Foo> foos;
for (const Foo& _ : foos) {
}
}
$ g++ /tmp/main4.cc -Wunused
/tmp/main4.cc: In function ‘void f()’:
/tmp/main4.cc:8:19: warning: unused variable ‘_’ [-Wunused-variable]
for (const Foo& _ : foos) {
^
> Is the type important, or specifics about the variable (e.g. the name?)
> The _ variable names are sometimes used for RAII variables/lambdas
> that shall just do some cleanup, e.g. gsl::finally().
>
> It might make sense to give ExprMutAnalyzer an ignore-mechanism.
>
> I wonder if instead there should be an option to not complain about the
> variables that aren't actually used?
>
> Checking for variable usage would be simple. The ExprMutAnalyzer
> always analyses the scope, e.g. a function. You can match this scope for
> a DeclRefExpr of the variable, empty result means no usage.
Both type and variable name "_" can fix the issue here, but the variable name
seems a fragile way (if the name is changed, things will be broken again).
Yeah, adding an ignore mechanism to ExprMutAnalyzer is another option.
Repository:
rCTE Clang Tools Extra
https://reviews.llvm.org/D50447
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