Bjarne Stroustrup: C++ Implementations - Clang, GCC, Microsoft, and EDG

Duration: 5:05 571 transcript words EN summary

Video summary

Bjarne Stroustrup explains that the existence of multiple C++ implementations, including GCC, Clang, Microsoft Visual C++, and EDG (Eclipse Development Group), was not a deliberate design choice but rather an inevitable reflection of the computing landscape when he created the language. In his early vision for C++, it was assumed that many different companies would develop their own compilers to run on various operating systems such as Sun, Motorola, and others, just as they did with older languages like PDP-11 or 86-based Linux boxes today. Stroustrup explicitly states he never intended a single implementation; instead, he anticipated the need for diverse front ends because users were already utilizing twenty-five different linkers alone, making it impossible to maintain compatibility without leveraging existing backend infrastructure from these varied sources. The necessity of supporting multiple compilers is further driven by the diversity of hardware architectures, particularly in the embedded systems industry where machines vary significantly and cannot be served by a single implementation. Stroustrup warns against "monocultures," arguing that when one entity controls an entire ecosystem, there is little incentive to innovate or improve performance because competitors are absent. He notes that owners of such monopolies often become stagnant and may erect barriers to change simply to protect their comfortable position. The presence of at least four distinct front ends today creates essential competition that pressures the standard committee regarding compliance, error messages, compile time speed, and overall optimization quality. Historically, GCC was a dominant force but eventually became somewhat stale before Clang emerged as a revitalizing competitor, forcing improvements in both areas. Similarly, Microsoft's implementation has evolved to become much better over time due to this competitive pressure. Stroustrup expresses satisfaction that the C++ ecosystem remains fragmented rather than unified under one provider, ensuring continuous advancement across all major platforms. This dynamic environment ensures that no single group can dictate terms without facing scrutiny from others who are actively working on alternative implementations and backends. Looking toward the future, while it is unlikely a completely new compiler will be written entirely from scratch given the extensive history of C++ standards versions 11 through 20, attempts to build fresh compilers continue to occur periodically. Some of these projects have been absorbed into larger ecosystems or used directly by specific communities before fading away or merging with others like LLVM-based solutions. Stroustrup acknowledges that someone will inevitably try again in the future to write a new C++ compiler from scratch, driven by the same necessity for innovation and adaptation that has characterized the language's development since its inception decades ago.

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it says there differences in your view not saying which is better or so on but difference in the different implementations of C++ why are there several sort of money of you naive questions for me GCC clang so this is a very reasonable question when I designed C++ most languages have multiple implementations because if you wanna I p.m. if you run on the Sun if you wanna Motorola those just many many companies and they each have their own compilation structure the old compilers it was just fairly common that those many of them and I wrote C front assuming that other people would write compilers for c++ if i was successful and furthermore i wanted to utilize all the backend infrastructure were available I soon realized that my users were using 25 different linkers I couldn't write my own linker yes I could but I couldn't write 25 linkers and also get any work done on the language and so it came from a world where there was many linkers many optimizers many compiler front ends not not to start but over at many operating systems the whole world was not an 86 and linux box or something whatever is the standard today in the old days they said a set of X so basically I assumed there'd be lots of compilers it was not a decision that there should be many compilers it was just a fact that's the way the world is and yes many compilers emerged and today there's at least four front ends clang GCC Microsoft and EDG it is the same group they they supply a lot of the independence organizations and the embedded systems industry and there's lots and lots of backends we have to think about how many dozen begins there are because different machines have different things especially in the embedded world the machines are very different the architectures are very different and so having a single implementation was never an option now I also haven't disliked monocultures monocultures they are dangerous because whoever owns the monoculture can go stale and there's no competition and there's no incentive to innovate there's a lot of incentive to put barriers in the way of change because hey we own the world and it's a very comfortable world for us and who are you to to mess with that so I really am very happy that there's four front ends for C++ clanks great but GCC was great but then it got somewhat stale plane came along and GCC is much better now competition why Microsoft is much better now so hello at least a low number of front end puts a lot of pressure on stand-ups compliance and also on performance and error messages and compile time speed all this good stuff that we want do you think crazy question there might come along you hope that might come along implementation of C++ written given all its history written from scratch so written today from scratch well playing and the LLVM as more less written by from scratch but there's been c++ 11 14 17 20 you know this is a lot you know later somebody's going to try again there has been attempts to write new C++ compilers and some of them has been used and some of them has been absorbed into others and so it's yeah it'll happen you