[cfe-dev] Clang effort

[David Chisnall]

On 16 Aug 2012, at 23:36, John Wiegley wrote:

>> That's hard to say.  One estimate from ohloh.net says it took 173 person
>> years at $9.5M: http://www.ohloh.net/p/clang/estimated_cost
> 
> Here's what sloccount estimates:
> 
> Total Physical Source Lines of Code (SLOC)                = 397,368
> Development Effort Estimate, Person-Years (Person-Months) = 107.20 (1,286.36)
> (Basic COCOMO model, Person-Months = 2.4 * (KSLOC**1.05))
> Schedule Estimate, Years (Months)                         = 3.16 (37.98)
> (Basic COCOMO model, Months = 2.5 * (person-months**0.38))
> Estimated Average Number of Developers (Effort/Schedule)  = 33.87
> Total Estimated Cost to Develop                           = $ 14,480,853
> (average salary = $56,286/year, overhead = 2.40).

Interesting that this estimates less time but more money than Ohloh.  I imagine the Ohloh estimate of time is more accurate, as it is tracking the entire revision control history.  Large parts of clang have been refactored or rewritten over the years as it becomes clear what the correct approach is, and it's very optimistic to assume that a new project would be able to avoid this and get to the correct solution (or, at least, one as correct as clang-TOT) on the first attempt.

David