https://issues.dlang.org/show_bug.cgi?id=23369

          Issue ID: 23369
           Summary: Confusing error message for duplicate import
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: jack@jackstouffer.com

import std.math : PI, PI;
void main() {}

Gives:

Error: alias `main.PI` conflicts with alias `main.PI` at main.d(1)

It should be something like

Error: `math.PI` imported multiple times at main.d(1)

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