[cfe-dev] clang-tidy and static analysis for exception safety

[Jonas Toth via cfe-dev]

Ok. So i will try to start with a prototype that can the basic stuff i 
think of. Is there a reference/example i can look into for the flow 
sensitivity? I am not experienced with clang-tidy, but want to become. 
:)

How would the analysis look like to see if a `catch` will actually 
catch all possible exceptions that could exist in the `try` block? 
Especially in destructors this is interesting for safety.

Am Do, 16. Mär, 2017 um 12:42 schrieb Manuel Klimek 
<klimek at google.com>:
> Yea, none of these seem to be path sensitive, but only flow 
> sensitive, which clang-tidy supports.
> 
> 
> On Thu, Mar 16, 2017 at 12:37 PM Jonas Toth via cfe-dev 
> <cfe-dev at lists.llvm.org> wrote:
>> Why would the second case not be possible?
>> What i have in mind by example:
>> 
>> ```
>> void definitly_throws() { // should be marked noexcept(false), maybe 
>> as configuration option
>> 	if (some_condition())
>> 		throw std::logic_error{"Reasons"};
>> 	else
>> 		// do unproblematic stuff
>> }
>> 
>> void probably_throws() { // this needs more analysis then AST 
>> matching so leave it as is
>> 	try  {
>> 		// operation
>> 		if (op_failed())
>> 			throw std::runtime_error{"Operation failed"};
>> 	}
>> 	catch (std::runtime_error& e)
>> 	{ /* handle */ }
>> }
>> ```
>> 
>> The second one can be noexcept if the operation will not throw. It 
>> is not noexcept if operation is not noexcept.
>> What did I miss?
>> 
>> The deeper analysis will not happen if the analyser does not see all 
>> code, but if it can shouldnt there the possibility to decide? Maybe 
>> it has bad complexity and is therefor not practical. But maybe in 
>> some cases there can be insight gained?
>> 
>> Am Do, 16. Mär, 2017 um 11:25 schrieb Daniel Marjamäki 
>> <Daniel.Marjamaki at evidente.se>:
>>> As far as I see:
>>> 
>>> 
>>> 
>>> - a function calling only `noexcept` operations that does not throw 
>>> can be marked noexcept
>>> 
>>> 
>>> 
>>> possible
>>> 
>>> 
>>> 
>>> - a function that has a `throw` statement not within a `try/catch` 
>>> block can be marked noexcept(false)
>>> 
>>> 
>>> 
>>> Not possible
>>> 
>>> 
>>> 
>>> - a function calling a function that is not marked noexcept can not 
>>> be marked noexcept
>>> 
>>>    but it could be noexecpt with deeper analysis on what exception 
>>> could be thrown and what exceptions are handled
>>> 
>>> 
>>> 
>>> not possible
>>> 
>> 
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