What's C's biggest mistake?

[Walter Bright]

Andrei Alexandrescu wrote:
> Walter Bright wrote:
>> Don wrote:
>>> Well, if you ask the question "what's C++'s biggest mistake?" it's 
>>> much more difficult. C++'s failure to specify the ABI is enough of a 
>>> reason to use C instead, I reckon. It think it's an appalling, 
>>> inexcusable mistake -- it guaranteed compiled libraries 20 years 
>>> later would use extern(C), not extern(C++). And that's not the worst 
>>> C++ mistake.
>>
>> I'd be hard pressed to come up with C++'s biggest mistake. Perhaps it 
>> was failing to address the array => pointer conversion.
> 
> That's partially addressed by the ability to define somewhat 
> encapsulated types like std::vector.

I agree that it is partially addressed by std::vector and std::string. But:

1. Those appeared 10 years after C++ was in widespread use, 10 years of 
wandering in the desert with everyone trying to invent their own string 
class.

2. It still reflects in the design of std::string, in that to preserve 
the 0 termination design, it makes severe compromises.

3. The glaring fact that std::vector<char> and std::string are different 
suggests something is still wrong.

4. The pointer-centric design resulted in std::iterator, and of course 
iterators must go!

> Don's suggested lack of ABI is big, 
> and unfortunately not addressed in C++0x. There are many smaller ones to 
> follow... two that come to mind: using "<"/">" for grouping and 
> argument-dependent lookup.

I would suggest a broader issue than < >, it is the willingness to 
require semantic analysis to successfully parse C++. < > would never 
have been used if that was not considered acceptable. Only later did the 
C++ community realize there was value in parsing things without semantic 
analysis, i.e. template bodies.

ADL was a fix for another issue, the asymmetric design of operator 
overloading. So I don't think ADL was a mistake so much as what C++ was 
forced into to compensate for a previous mistake.