4 ms·

Pretty much any existing C compiler will also solve that problem by telling you that it's uninitialized.

WalterBright 10mo ago
I tried: int test() { int i; return i; } using clang on my Mac mini, and: clang -c test.c and it compiled without complaint.
- pseudohadamard 10mo ago
  I always build with -Wall so I'm used to seeing the warning: > clang -Wall test.c test.c:4:16: warning: variable 'i' is uninitialized when used here [-Wuninitialized] 4 | return i; | ^ test.c:3:14: note: initialize the variable 'i' to silence this warning 3 | int i; | ^ | = 0 1 warning generated. For the oldest compiler I have access to, VC++ 6.0 from 1998: warning C4700: uninitialized local variable 'i' used
  - WalterBright 10mo ago
    The trouble with warnings is every compiler has a different set of warnings. It balkanizes the language. Many D features are the result of cherry picking warnings from various compilers and making them standard features.
    - 1718627440 10mo ago
      > It balkanizes the language. Not really, as C has had even more diverse implementations per-standardization. I would say the situation is now, much less diverse under the rule of GCC and Clang. (Yeah MSVC also exists.)
      - WalterBright 10mo ago
        Every switch that changes the language semantics creates a separate language. If you have n such switches, your compiler is supporting n x n languages. I've also had troubles writing portable C code with all warnings enabled as different compilers contradicted each other on what was acceptable. I tried pretty hard to make D a warning-less language, but still some crept in grump grump. Have fun with this one: for (int i = 0; i < end; ++i); foo(i); One of the best programmers I know came up to me with this loop and told me my C compiler was broken because the loop was only executed once. I pointed at the ; and you can guess the rest. I added a warning for that in the C compiler, and for D simply disallowed it. I've noticed that some C compilers have since added a warning for that as well. The C folks should just make it illegal. I've also fixed printf in D so that: char* p; printf("%d\n", p); gives an error message, and the right format to use for `p`. It was a little thing, but it sure found a lot of incorrect formats in my code.
        1718627440 10mo ago
        > The C folks should just make it illegal. I often have code, which looks like this: for (ptr = start; random_condition (*ptr); ptr = ptr->next); for (ptr = ptr->next; other_condition (*ptr); ptr = ptr->prev); ... [do action] for (ptr = end; to_be_deleted (*ptr) && (delete (ptr), TRUE); ptr = ptr->prev); I wouldn't be happy about your policy. > I've also fixed printf in D so that [...] gives an error message Just last week I had the case that the C compiler complained, I should use %lld for long long, but the printf implementation shipped with the compiler doesn't support that. Thus, using %ld, even if undefined behaviour was the correct action. I wouldn't like my language making up more work for me for no reason.
        WalterBright 10mo ago
        Rewrite as: for (ptr = start; random_condition (*ptr); ptr = ptr->next) { } Then anyone reading your code will know the empty loop was intentional. BTW, many C compilers warn about the ; on a for loop. Have you ever discovered this bug: if (condition); doThis(); It's a hard one to see in a code review. Yes, that's also disallowed in D. > I should use %lld for long long, but the printf implementation shipped with the compiler doesn't support that. Weird that your compiler would support long long, but with a broken Standard library. I don't see that as a feature. You can always cast the argument to long, and at least you won't get undefined behavior.
    - pseudohadamard 10mo ago
      I see this as a feature, not a bug. I compile my code with a range of different compilers because each one catches things the others don't. The creeping gcc-isation of everything is what I'd see as a bug.
- 1718627440 10mo ago
  C compilers without arguments start in 'trust me and shut up mode'. Seems to be sensible to me, because the 'I don't care about correctness' typically coincides with writing throwaway code, while you surely have the time to add compiler arguments when you set up the build system for an actual project.
  - WalterBright 10mo ago
    Or just have the language initialize it for you!
    - 1718627440 10mo ago
      Thanks, I very much don't want that. There are also people (like me) who find the C semantics pretty great.
      - WalterBright 10mo ago
        > I very much don't want that Why? What does it cost you?
        1718627440 10mo ago
        Making something a valid program that shouldn't be. Thus, potentially creating/hiding bugs. I also explicitly invoke UB on all the code paths I do not want to be valid.
        WalterBright 10mo ago
        I've had the pleasure of spending many hours hunting down an uninitialized variable, as its value would change anytime I got close to it. BTW, if you really, really, want an uninitialized variable: int x = void; will do it.
        fc417fc802 10mo ago

I tried: int test() { int i; return i; } using clang on my Mac mini, and: clang -c test.c and it compiled without complaint.

pseudohadamard 10mo ago
I always build with -Wall so I'm used to seeing the warning: > clang -Wall test.c test.c:4:16: warning: variable 'i' is uninitialized when used here [-Wuninitialized] 4 | return i; | ^ test.c:3:14: note: initialize the variable 'i' to silence this warning 3 | int i; | ^ | = 0 1 warning generated. For the oldest compiler I have access to, VC++ 6.0 from 1998: warning C4700: uninitialized local variable 'i' used
- WalterBright 10mo ago
  The trouble with warnings is every compiler has a different set of warnings. It balkanizes the language. Many D features are the result of cherry picking warnings from various compilers and making them standard features.
  - 1718627440 10mo ago
    > It balkanizes the language. Not really, as C has had even more diverse implementations per-standardization. I would say the situation is now, much less diverse under the rule of GCC and Clang. (Yeah MSVC also exists.)
    - WalterBright 10mo ago
      Every switch that changes the language semantics creates a separate language. If you have n such switches, your compiler is supporting n x n languages. I've also had troubles writing portable C code with all warnings enabled as different compilers contradicted each other on what was acceptable. I tried pretty hard to make D a warning-less language, but still some crept in grump grump. Have fun with this one: for (int i = 0; i < end; ++i); foo(i); One of the best programmers I know came up to me with this loop and told me my C compiler was broken because the loop was only executed once. I pointed at the ; and you can guess the rest. I added a warning for that in the C compiler, and for D simply disallowed it. I've noticed that some C compilers have since added a warning for that as well. The C folks should just make it illegal. I've also fixed printf in D so that: char* p; printf("%d\n", p); gives an error message, and the right format to use for `p`. It was a little thing, but it sure found a lot of incorrect formats in my code.
      - 1718627440 10mo ago
        > The C folks should just make it illegal. I often have code, which looks like this: for (ptr = start; random_condition (*ptr); ptr = ptr->next); for (ptr = ptr->next; other_condition (*ptr); ptr = ptr->prev); ... [do action] for (ptr = end; to_be_deleted (*ptr) && (delete (ptr), TRUE); ptr = ptr->prev); I wouldn't be happy about your policy. > I've also fixed printf in D so that [...] gives an error message Just last week I had the case that the C compiler complained, I should use %lld for long long, but the printf implementation shipped with the compiler doesn't support that. Thus, using %ld, even if undefined behaviour was the correct action. I wouldn't like my language making up more work for me for no reason.
        WalterBright 10mo ago
        Rewrite as: for (ptr = start; random_condition (*ptr); ptr = ptr->next) { } Then anyone reading your code will know the empty loop was intentional. BTW, many C compilers warn about the ; on a for loop. Have you ever discovered this bug: if (condition); doThis(); It's a hard one to see in a code review. Yes, that's also disallowed in D. > I should use %lld for long long, but the printf implementation shipped with the compiler doesn't support that. Weird that your compiler would support long long, but with a broken Standard library. I don't see that as a feature. You can always cast the argument to long, and at least you won't get undefined behavior.
  - pseudohadamard 10mo ago
    I see this as a feature, not a bug. I compile my code with a range of different compilers because each one catches things the others don't. The creeping gcc-isation of everything is what I'd see as a bug.
1718627440 10mo ago
C compilers without arguments start in 'trust me and shut up mode'. Seems to be sensible to me, because the 'I don't care about correctness' typically coincides with writing throwaway code, while you surely have the time to add compiler arguments when you set up the build system for an actual project.
- WalterBright 10mo ago
  Or just have the language initialize it for you!
  - 1718627440 10mo ago
    Thanks, I very much don't want that. There are also people (like me) who find the C semantics pretty great.
    - WalterBright 10mo ago
      > I very much don't want that Why? What does it cost you?
      - 1718627440 10mo ago
        Making something a valid program that shouldn't be. Thus, potentially creating/hiding bugs. I also explicitly invoke UB on all the code paths I do not want to be valid.
        WalterBright 10mo ago
        I've had the pleasure of spending many hours hunting down an uninitialized variable, as its value would change anytime I got close to it. BTW, if you really, really, want an uninitialized variable: int x = void; will do it.
        fc417fc802 10mo ago