[PATCH] D25266: Add a static_assert to enforce that parameters to llvm::format() are not totally unsafe

[Mehdi Amini via llvm-commits]

So we capture the format in a “const char *” and it is obviously not available for sanitizing by the time we use it to call snprintf.

Any other idea?

> On Oct 5, 2016, at 6:11 PM, Mehdi Amini via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> That’s a good idea, unfortunately: "error: format attribute requires variadic function”.
> 
> Also since we end up calling snprintf, I wonder why we don’t already catch these there, it is correctly decorated with the attribute on Darwin. Issue with variadic template (or template alone)? I should try a minimal test case.
> 
>  
>> On Oct 5, 2016, at 9:35 AM, Zachary Turner <zturner at google.com <mailto:zturner at google.com>> wrote:
>> 
>> Can't you add __attribute__((format(printf))); to the constructor?  That would catch these issues.
>> 
>> On Wed, Oct 5, 2016 at 9:05 AM Mehdi AMINI via llvm-commits <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
>> mehdi_amini added a comment.
>> 
>> This is also catching existing latent bugs in the codebase:
>> 
>>   In file included from /llvm-project/llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp:55:
>>   /llvm-project/llvm/include/llvm/Support/Format.h:82:3: error: static_assert failed "format can't be used with non fundamental / non pointer type"
>>     static_assert(std::is_scalar<Arg>::value,
>>     ^             ~~~~~~~~~~~~~~~~~~~~~~~~~~
>>   /llvm-project/llvm/include/llvm/Support/Format.h:105:5: note: in instantiation of template class 'llvm::validate_format_parameters<llvm::StringRef>' requested here
>>       validate_format_parameters<Ts...>();
>>       ^
>>   /llvm-project/llvm/include/llvm/Support/Format.h:124:10: note: in instantiation of member function 'llvm::format_object<llvm::StringRef>::format_object' requested here
>>     return format_object<Ts...>(Fmt, Vals...);
>>            ^
>>   /llvm-project/llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp:965:21: note: in instantiation of function template specialization 'llvm::format<llvm::StringRef>' requested here
>>       DEBUG(dbgs() << format("  %14s  ", TII->getName(MI->getOpcode())));
>> 
>> 
>> https://reviews.llvm.org/D25266 <https://reviews.llvm.org/D25266>
>> 
>> 
>> 
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