[Issue 23019] New: Missing filename when -of points to an existing directory

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23019

          Issue ID: 23019
           Summary: Missing filename when -of points to an existing
                    directory
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: regression
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: moonlightsentinel at disroot.org

Trying to write the binary to an existing directory with -of yields a broken
error message:

---
mkdir src
dmd -c -of=src stuff.d
---
Error: Error writing file '   '

Note the '   '  instead of 'src'.

This is a regression introduced by https://github.com/dlang/dmd/pull/9751

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