internal/lsp: provide arguments deterministically to packages.Load

This is just to ensure that arguments are always ordered when passed to
packages.Load.

Change-Id: I2c74673eff31efc31854dc0d306809890f633789
Reviewed-on: https://go-review.googlesource.com/c/tools/+/216600
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/lsp/cache/load.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"fmt"
 	"go/types"
+	"sort"
 	"strings"
 
 	"golang.org/x/tools/go/packages"
@@ -41,14 +42,10 @@ func (s *snapshot) load(ctx context.Context, scopes ...interface{}) ([]*metadata
 	var query []string
 	for _, scope := range scopes {
 		switch scope := scope.(type) {
-		case []packagePath:
+		case packagePath:
 			// The only time we pass package paths is when we're doing a
 			// partial workspace load. In those cases, the paths came back from
 			// go list and should already be GOPATH-vendorized when appropriate.
-			for _, p := range scope {
-				query = append(query, string(p))
-			}
-		case packagePath:
 			query = append(query, string(scope))
 		case fileURI:
 			query = append(query, fmt.Sprintf("file=%s", span.URI(scope).Filename()))
@@ -74,6 +71,8 @@ func (s *snapshot) load(ctx context.Context, scopes ...interface{}) ([]*metadata
 			panic(fmt.Sprintf("unknown scope type %T", scope))
 		}
 	}
+	sort.Strings(query) // for determinism
+
 	ctx, done := trace.StartSpan(ctx, "cache.view.load", telemetry.Query.Of(query))
 	defer done()