[Issue 13986] New: auto return for some recursive functions

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13986

          Issue ID: 13986
           Summary: auto return for some recursive functions
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: DMD
          Assignee: nobody at puremagic.com
          Reporter: bearophile_hugs at eml.cc

According to Wikipedia:
http://en.wikipedia.org/wiki/C%2B%2B14#Function_return_type_deduction

C++14 is able to compile code like this:



auto correct(int i) {
    if (i == 1)
        return i;
    else
        return correct(i - 1) + i;
}


But not like this:

auto correct(int i) {
    if (i != 1)
        return correct(i - 1) + i;
    else
        return i;
}


D isn't able to compile both. Is it possible and a good idea to allow the first
function in D too?

The D spec says:

"If multiple return expressions are used in the function's implementation, then
they must all deduce the same type."

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