"I made a game using Rust"

[Adam D. Ruppe via Digitalmars-d]

On Wednesday, 10 May 2017 at 14:02:38 UTC, Adrian Matoga wrote:
> Would you mind giving some examples?

What bothers me on a regular basis is overloading. Basic case:

$ dmd lll
lll.d(6): Error: none of the overloads of 'foo' are callable 
using argument types (int, double), candidates are:
lll.d(1):        lll.foo(int a, int a)
lll.d(2):        lll.foo(int a, string s)

Contrast that to g++:

$ g++ lll.cpp
lll.cpp: In function ‘int main()’:
lll.cpp:7:14: error: no matching function for call to ‘foo(int, 
Foo)’
   foo(0, Foo());
               ^
lll.cpp:7:14: note: candidates are:
lll.cpp:1:6: note: void foo(int, char*)
  void foo(int a, char* b);
       ^
lll.cpp:1:6: note:   no known conversion for argument 2 from 
‘Foo’ to ‘char*’
lll.cpp:2:6: note: void foo(int, float)
  void foo(int a, float b);
       ^
lll.cpp:2:6: note:   no known conversion for argument 2 from 
‘Foo’ to ‘float’



The g++ example isn't great either... but is better because of 
this: "no known conversion for argument 2 from ‘Foo’ to ‘float’"


It actually told me which argument didn't match! clang is similar:

$ clang lll.cpp
lll.cpp:7:2: error: no matching function for call to 'foo'
         foo(0, Foo());
         ^~~
lll.cpp:1:6: note: candidate function not viable: no known 
conversion from 'Foo' to 'char *' for 2nd argument
void foo(int a, char* b);
      ^
lll.cpp:2:6: note: candidate function not viable: no known 
conversion from 'Foo' to 'float' for 2nd argument
void foo(int a, float b);



With the dmd one, especially on a long function, it is hard to 
tell just which argument is giving trouble. The C++ errors just 
flat out tell me which argument didn't match for each candidate.



Templates with constraints are even worse.

lll.d(3): Error: template std.algorithm.sorting.sort cannot 
deduce function from argument types !()(int), candidates are:
/home/me/d/dmd2/linux/bin32/../../src/phobos/std/algorithm/sorting.d(1830):        std.algorithm.sorting.sort(alias less = "a < b", SwapStrategy ss = SwapStrategy.unstable, Range)(Range r) if ((ss == SwapStrategy.unstable && (hasSwappableElements!Range || hasAssignableElements!Range) || ss != SwapStrategy.unstable && hasAssignableElements!Range) && isRandomAccessRange!Range && hasSlicing!Range && hasLength!Range)


What a mess! Just formatting that output might help, but I'd 
especially love it if it told me which individual boolean 
elements failed, passed, and were short-circuited. The compiler 
knows this, it had to evaluate that to figure out it didn't 
match, but it doesn't tell me.

At a glance, can you even tell what I passed to the function?

Bonus points would be it telling me why, for example, 
`isInputRange` failed, but I understand that is an even bigger 
problem to solve.

Of course, C++ doesn't have constraints so there's no comparison 
there.


Lastly, check this out:

lll.d(5): Error: function lll.foo (Color c) is not callable using 
argument types (Color)

WTF, right? Well, I have a locally defined `struct Color` and an 
imported one. Same name, but different type. The error message 
doesn't tell me which one is which.




These are the top 3 dmd error messages that bother me regularly. 
At runtime, little drives me more nuts than RangeError not 
telling me the index and the length. Again, it knows, the code 
checked it, but it didn't report it.