internal/lsp: add type error fixes to existing diagnostics

This change is the first step in handling golang/go#38136. Instead of
creating multiple diagnostic reports for type error analyzers, we add
suggested fixes to the existing reports. To match the analyzers for
FindAnalysisError, we add an ErrorMatch function to source.Analyzer.

This is not an ideal solution, but it was the best one I could come up
with without modifying the go/analysis API. analysisinternal could be
used for this purpose, but it seemed to complicated to be worth it, and
this is fairly simple. I think that go/analysis itself might need to be
extended for type error analyzers, but these temporary measures will
help us understand the kinds of features we need for type error
analyzers.

A follow-up CL might be to not add reports for type error analyzers
until the end of source.Diagnostic, which would remove the need for the
look-up.

Fixes golang/go#38136

Change-Id: I25bc6396b09d49facecd918bf5591d2d5bdf1b3a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/226777
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

1 files changed, 43 insertions, 4 deletions

diff --git a/internal/lsp/code_action.go b/internal/lsp/code_action.go
index e12537556..4757a1ee1 100644
--- a/internal/lsp/code_action.go
+++ b/internal/lsp/code_action.go
@@ -259,10 +259,8 @@ func analysisFixes(ctx context.Context, snapshot source.Snapshot, fh source.File
 		return nil, nil, err
 	}
 	for _, diag := range diagnostics {
-		// This code assumes that the analyzer name is the Source of the diagnostic.
-		// If this ever changes, this will need to be addressed.
-		srcErr, analyzer, err := snapshot.FindAnalysisError(ctx, ph.ID(), diag.Source, diag.Message, diag.Range)
-		if err != nil {
+		srcErr, analyzer, ok := findSourceError(ctx, snapshot, ph.ID(), diag)
+		if !ok {
 			continue
 		}
 		for _, fix := range srcErr.SuggestedFixes {
@@ -289,6 +287,47 @@ func analysisFixes(ctx context.Context, snapshot source.Snapshot, fh source.File
 	return codeActions, sourceFixAllEdits, nil
 }
 
+func findSourceError(ctx context.Context, snapshot source.Snapshot, pkgID string, diag protocol.Diagnostic) (*source.Error, source.Analyzer, bool) {
+	var analyzer *source.Analyzer
+
+	// If the source is "compiler", we expect a type error analyzer.
+	if diag.Source == "compiler" {
+		for _, a := range snapshot.View().Options().TypeErrorAnalyzers {
+			if a.FixesError(diag.Message) {
+				analyzer = &a
+				break
+			}
+		}
+	} else {
+		// This code assumes that the analyzer name is the Source of the diagnostic.
+		// If this ever changes, this will need to be addressed.
+		if a, ok := snapshot.View().Options().DefaultAnalyzers[diag.Source]; ok {
+			analyzer = &a
+		}
+	}
+	if analyzer == nil || !analyzer.Enabled(snapshot) {
+		return nil, source.Analyzer{}, false
+	}
+	analysisErrors, err := snapshot.Analyze(ctx, pkgID, analyzer.Analyzer)
+	if err != nil {
+		return nil, source.Analyzer{}, false
+	}
+	for _, err := range analysisErrors {
+		if err.Message != diag.Message {
+			continue
+		}
+		if protocol.CompareRange(err.Range, diag.Range) != 0 {
+			continue
+		}
+		if err.Category != analyzer.Analyzer.Name {
+			continue
+		}
+		// The error matches.
+		return err, *analyzer, true
+	}
+	return nil, source.Analyzer{}, false
+}
+
 func documentChanges(fh source.FileHandle, edits []protocol.TextEdit) []protocol.TextDocumentEdit {
 	return []protocol.TextDocumentEdit{
 		{