lsp: emit VS-internal HiddenInEditor tag for unnecessary diagnostics#3989
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joj wants to merge 2 commits into
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lsp: emit VS-internal HiddenInEditor tag for unnecessary diagnostics#3989joj wants to merge 2 commits into
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Pull request overview
Note
Copilot was unable to run its full agentic suite in this review.
This PR updates LSP diagnostic tagging to make “Unnecessary” diagnostics render as faded (no squiggle) in Visual Studio by emitting a VS-specific extension tag when the client indicates VS extension support, while keeping standard LSP behavior for other clients.
Changes:
- Added a VS-specific
DiagnosticTagconstant (HiddenInEditor) in the LSP protocol layer. - Updated diagnostic conversion to append
HiddenInEditoralongsideUnnecessarywhen talking to Visual Studio.
Show a summary per file
| File | Description |
|---|---|
| internal/lsp/lsproto/lsp.go | Introduces a VS-specific diagnostic tag constant used to influence VS rendering. |
| internal/ls/lsconv/converters.go | Emits the VS extension diagnostic tag (in addition to Unnecessary) when the client is Visual Studio. |
Copilot's findings
- Files reviewed: 2/2 changed files
- Comments generated: 2
jakebailey
reviewed
May 19, 2026
The LSP spec says clients are "allowed to render diagnostics [tagged Unnecessary] faded out instead of having an error squiggle." Visual Studio's LSP client, however, only renders the faded "unused" appearance when a diagnostic carries both DiagnosticTag.Unnecessary AND the VS-internal VSDiagnosticTags.HiddenInEditor tag; with just Unnecessary the diagnostic shows as a normal squiggle. When the client advertises _vs_supportsVisualStudioExtensions, also emit HiddenInEditor (int32.MaxValue - 6 = 2147483641) so unused variables and similar diagnostics render faded in Visual Studio. Non-VS clients continue to receive only the standard LSP tags. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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| tags = make([]lsproto.DiagnosticTag, 0, 3) | ||
| if diagnostic.ReportsUnnecessary() && slices.Contains(opts.tagValueSet, lsproto.DiagnosticTagUnnecessary) { | ||
| tags = append(tags, lsproto.DiagnosticTagUnnecessary) | ||
| // Visual Studio's LSP client only renders Unnecessary diagnostics as | ||
| // faded-out text when they also carry the VS-internal HiddenInEditor | ||
| // tag; otherwise they appear as a regular squiggle. Emit it so VS | ||
| // matches the LSP-spec intent of the Unnecessary tag. | ||
| if opts.visualStudio { | ||
| tags = append(tags, lsproto.DiagnosticTagVsHiddenInEditor) | ||
| } |
Co-authored-by: Jake Bailey <5341706+jakebailey@users.noreply.github.com>
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The LSP spec says clients are "allowed to render diagnostics [tagged Unnecessary] faded out instead of having an error squiggle." Visual Studio's LSP client, however, only renders the faded "unused" appearance when a diagnostic carries both DiagnosticTag.Unnecessary AND the VS-internal VSDiagnosticTags.HiddenInEditor tag; with just Unnecessary the diagnostic shows as a normal squiggle.
When the client advertises _vs_supportsVisualStudioExtensions, also emit HiddenInEditor (int32.MaxValue - 6 = 2147483641) so unused variables and similar diagnostics render faded in Visual Studio. Non-VS clients continue to receive only the standard LSP tags.