Bug 8634 – Anonymous function parameters

void foo(int) { } void main() { foo(5); } Although anonymous function parameters may be used in function declarations, it seems that dmd doesn't check whether a function declaration is a definition too.

(In reply to comment #0) > void foo(int) > { > > } > > void main() > { > foo(5); > } > > Although anonymous function parameters may be used in function declarations, it > seems that dmd doesn't check whether a function declaration is a definition > too. What's the problem here? foo() not giving a name to its first argument means the programmer is stating foo() never uses its first argument, and the D language allows the programmer to enforce this desire. This feature also allows to avoid "unused argument warnings" once/where such warning is available.

(In reply to comment #1) > (In reply to comment #0) > > void foo(int) > > { > > > > } > > > > void main() > > { > > foo(5); > > } > > > > Although anonymous function parameters may be used in function declarations, it > > seems that dmd doesn't check whether a function declaration is a definition > > too. > > What's the problem here? > > foo() not giving a name to its first argument means the programmer is stating > foo() never uses its first argument, and the D language allows the programmer > to enforce this desire. > > This feature also allows to avoid "unused argument warnings" once/where such > warning is available. The problem is that such code is likely to be a bug (parameter name was forgotten) and compiler should report about this. BTW dmd doesn't produce any warning for unused variable.

(In reply to comment #2) > The problem is that such code is likely to be a bug (parameter name was > forgotten) and compiler should report about this. I care a lot about removing bug-prone situations from D language. And I think C# language acts as you ask. Generally C# designers are very careful in avoiding bug-prone features. But in general it's not so common to forget to add a name for the argument. And even in the cases where I have forgotten to put the argument name, this is usually not a big problem, because the compiler doesn't find the name you are using inside the function, and gives you a nice compilation error at the first usage attempt, close enough to the function signature (unless your functions are really long). In theory one bug-prone situation is when you use a name thinking it's the name of a local argument, while you have not given a name to the argument, and you have a name in an outer scope that is the same. So you are actually using the name of the outer scope. In practice my diary of bugs shows I have never hit this bug, also because it's generally a good practice to not define local names equal to outer names. So unless you have evidence that this is a common enough bug (even few anecdotes are enough to keep this discussion open) I think this bug report should be closed. > BTW dmd doesn't produce any warning for unused variable. I know, but probably someday some D compiler will report them. It's an useful feature and it's not too much hard to implement. All the major C++ compilers have an option to report them. But note here I was not referring to a generic "unused variable" warning, I was referring to more specifically to a "unused argument" warning. If you omit the argument name, the warning is silenced.

I have no desire for disputes about things which are not necessarily defective (as revealed here) and claimed by D people to be intentional part of the language.