[Issue 21520] New: dmd does not honor the NO_COLOR environment variable

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21520

          Issue ID: 21520
           Summary: dmd does not honor the NO_COLOR environment variable
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: ibuclaw at gdcproject.org

All command-line software which outputs text with ANSI color added should check
for the presence of a NO_COLOR environment variable that, when present
(regardless of its value), prevents the addition of ANSI color.

Currently, dmd only supports `-color=off`.

See: https://no-color.org/

For context: https://github.com/dlang/dmd/pull/11110#issuecomment-753420180

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