internal/lsp: track diagnostics by reporting source

Our handling of diagnostics has gotten complicated and has recently been
a source of bugs. Heschi and I took a step back and refactored the
diagnostic pass, starting with a new data structure for tracking

The LSP server now holds a map of URI to collection of diagnostic
reports, which is used to track diagnostics as they are computed by
multiple sources. Additionally, this collection holds a hash of the
last published diagnostic set.

This new information allows us to implement an algorithm for
incrementally updating diagnostics on the server: diagnostics reports
are stored as they are computed for a snapshot, and then published in
(possibly multiple) passes, with the last pass for a snapshot being
marked as 'final'.  In non-final passes, 'publishReports' publishes any
diagnostics that have already been computed for the snapshot, but does
nothing with URIs for which no diagnostics have been computed. In final
passes all diagnostics are reported, with empty diagnostics being
published for any URIs with no diagnostic reports. Any URIs for which no
diagnostic reports were computed are pruned from the diagnostic set. In
all cases, tracking the hash of published diagnostics prevents us from
duplicate publication.

This enables some simplifications of the existing diagnostic logic.
Computing new diagnostics and tracking send diagnostics is now handled
by the same algorithm, avoiding some bookkeeping. It is also no longer
necessary to explicitly clear diagnostics for deletions. This fixes some
previously broken edge cases, for example when packages go out of scope
due to go.mod or gopls.mod changes.

Fixes golang/go#42198

Change-Id: Id0d8d0f7a60f6ffa8c33f0ae41763461f61dab7b
Run-TryBot: Robert Findley <>
gopls-CI: kokoro <>
TryBot-Result: Go Bot <>
Reviewed-by: Rebecca Stambler <>
Trust: Robert Findley <>
9 files changed
tree: 3e016108150bb710ce0d6f890d43d0597038560d
  1. .gitattributes
  2. .gitignore
  3. .prettierrc
  10. benchmark/
  11. blog/
  12. cmd/
  13. codereview.cfg
  14. container/
  15. cover/
  16. go.mod
  17. go.sum
  18. go/
  19. godoc/
  20. gopls/
  21. imports/
  22. internal/
  23. playground/
  24. present/
  25. refactor/
  26. txtar/

Go Tools

This subrepository holds the source for various packages and tools that support the Go programming language.

Some of the tools, godoc and vet for example, are included in binary Go distributions.

Others, including the Go guru and the test coverage tool, can be fetched with go get.

Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.


The easiest way to install is to run go get -u You can also manually git clone the repository to $GOPATH/src/

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The version of prettier used is 1.18.2.

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