internal/lsp: match completions case-insensitively

Change-Id: I31f2ea338ae3e2ec2837a444705f990e140ebc77
Reviewed-on: https://go-review.googlesource.com/c/tools/+/184159
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>

internal/lsp/completion.go

@@ -67,16 +67,21 @@ func (s *Server) completion(ctx context.Context, params *protocol.CompletionPara
 const maxDeepCompletions = 3
 
 func toProtocolCompletionItems(candidates []source.CompletionItem, prefix string, rng protocol.Range, insertTextFormat protocol.InsertTextFormat, usePlaceholders bool, useDeepCompletions bool) []protocol.CompletionItem {
+	// Sort the candidates by score, since that is not supported by LSP yet.
 	sort.SliceStable(candidates, func(i, j int) bool {
 		return candidates[i].Score > candidates[j].Score
 	})
+
+	// Matching against the prefix should be case insensitive.
+	prefix = strings.ToLower(prefix)
+
 	var (
 		items                  = make([]protocol.CompletionItem, 0, len(candidates))
 		numDeepCompletionsSeen int
 	)
 	for i, candidate := range candidates {
-		// Match against the label.
-		if !strings.HasPrefix(candidate.Label, prefix) {
+		// Match against the label (case-insensitive).
+		if !strings.HasPrefix(strings.ToLower(candidate.Label), prefix) {
 			continue
 		}
 

internal/lsp/source/source_test.go

@@ -152,19 +152,19 @@ func (r *runner) Completion(t *testing.T, data tests.Completions, snippets tests
 		if err != nil {
 			t.Fatalf("failed for %v: %v", src, err)
 		}
+		var prefix string
+		if surrounding != nil {
+			prefix = strings.ToLower(surrounding.Prefix())
+		}
 		wantBuiltins := strings.Contains(string(src.URI()), "builtins")
 		var got []source.CompletionItem
 		for _, item := range list {
 			if !wantBuiltins && isBuiltin(item) {
 				continue
 			}
-			var prefix string
-			if surrounding != nil {
-				prefix = surrounding.Prefix()
-			}
 			// We let the client do fuzzy matching, so we return all possible candidates.
 			// To simplify testing, filter results with prefixes that don't match exactly.
-			if !strings.HasPrefix(item.Label, prefix) {
+			if !strings.HasPrefix(strings.ToLower(item.Label), prefix) {
 				continue
 			}
 			got = append(got, item)

internal/lsp/testdata/errors/errors.go

@@ -1,5 +1,10 @@
 package errors
 
+import (
+	"golang.org/x/tools/internal/lsp/types"
+)
+
 func _() {
 	bob.Bob() //@complete(".")
+	types.b //@complete(" //", Bob_interface)
 }

internal/lsp/tests/tests.go

@@ -25,7 +25,7 @@ import (
 // We hardcode the expected number of test cases to ensure that all tests
 // are being executed. If a test is added, this number must be changed.
 const (
-	ExpectedCompletionsCount       = 136
+	ExpectedCompletionsCount       = 137
 	ExpectedCompletionSnippetCount = 15
 	ExpectedDiagnosticsCount       = 17
 	ExpectedFormatCount            = 5