[Issue 22889] New: Selective import shadows local variable

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=22889

          Issue ID: 22889
           Summary: Selective import shadows local variable
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: snarwin+bugzilla at gmail.com

As of DMD 2.099.0, the following program compiles and runs without error:

--- lib.d
int x = 1;

--- main.d
void main()
{
    int x = 2;    
    {
        import lib : x;
        assert(x == 1);
    }
}
---

The language spec [1] states that name lookup proceeds in two phases: first,
symbols in the current module and inherited scopes are considered; second,
imported symbols are considered. It is not stated explicitly whether
selectively-imported symbols are considered in phase 1 or phase 2.

If selectively-imported symbols are considered in phase 1, the above program
should yield a compile-time error, because symbols are not permitted to shadow
other symbols declared in the same function.

If selectively-imported symbols are considered in phase 2, the above program
should yield a runtime error, because the local `x` should hide the imported
`x`.

Either way, the observed behavior cannot possibly be correct.

[1] https://dlang.org/spec/module.html#name_lookup

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