global using in shared globals and IDE0005: Using directive is unnecessary.

[ptr727]

I have a shared cs file where I use global using foo = foo4 entries.
These are used for versioned JSON serialization classes, and I "typedef" the generic name to the latest version of the schema.
I share this .cs file across projects.

In this file:

// Current schema version is v4
global using ConfigFileJsonSchema = PlexCleaner.ConfigFileJsonSchema4;

// Current schema version is v4
// TODO: info IDE0005: Using directive is unnecessary.
global using SidecarFileJsonSchema = PlexCleaner.SidecarFileJsonSchema4;

dotnet format --verify-no-changes --severity=info --verbosity=detailed reports IDE0005: Using directive is unnecessary. for the second entry, not the first, and removing the second entry breaks compilation.

I looked at IDE0005 docs, did not see anything of interest.

Is this something I can fix, or is it a bug?

[vst121]

Hi! 👋

What you’re seeing is actually a known quirk with IDE0005 when it comes to global using aliases.

• Even though your alias SidecarFileJsonSchema is used indirectly across projects, the analyzer sometimes cannot detect usage in other projects when the file is shared, so it flags it as “unnecessary.”
• The first alias doesn’t trigger the warning because it’s either referenced in the same project or in a way the analyzer can track.
• Removing the alias breaks compilation, so it’s definitely still needed.

So in short:

• It’s not a code error, your usage is correct.
• It’s likely an analyzer/IDE bug (or limitation).
• Workarounds:
  1. Suppress IDE0005 for that line with #pragma warning disable IDE0005 … #pragma warning restore
  2. Keep the alias — the compiler is happy; the warning is just cosmetic

Reference: IDE0005 docs
note that global usings can sometimes be flagged incorrectly when used across multiple projects.

Hope that help!