gopls/internal/vulncheck: handle package errors

x/tools/go/packages.Load can succeed even when the packages have
errors. vulncheck analysis requires clean build for the analyzed
code. So, check returned packages and stop if any of them has
errors.

Change-Id: I25a272631aa80f0c22abb00cf52776db2640cb80
Reviewed-on: https://go-review.googlesource.com/c/tools/+/454437
gopls-CI: kokoro <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: hyangah

gopls/internal/regtest/misc/vuln_test.go

@@ -56,6 +56,40 @@ package foo
 	})
 }
 
+func TestRunGovulncheckError2(t *testing.T) {
+	const files = `
+-- go.mod --
+module mod.com
+
+go 1.12
+-- foo.go --
+package foo
+
+func F() { // build error incomplete
+`
+	WithOptions(
+		EnvVars{
+			"_GOPLS_TEST_BINARY_RUN_AS_GOPLS": "true", // needed to run `gopls vulncheck`.
+		},
+		Settings{
+			"codelenses": map[string]bool{
+				"run_govulncheck": true,
+			},
+		},
+	).Run(t, files, func(t *testing.T, env *Env) {
+		env.OpenFile("go.mod")
+		var result command.RunVulncheckResult
+		env.ExecuteCodeLensCommand("go.mod", command.RunGovulncheck, &result)
+		env.Await(
+			OnceMet(
+				CompletedProgress(result.Token),
+				// TODO(hyangah): find a way to inspect $/progress 'report' message.
+				LogMatching(protocol.Info, "failed to load packages due to errors", 1, false),
+			),
+		)
+	})
+}
+
 const vulnsData = `
 -- GO-2022-01.yaml --
 modules:

gopls/internal/vulncheck/command.go

@@ -10,6 +10,7 @@ package vulncheck
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"log"
 	"os"
@@ -91,7 +92,6 @@ func (c *Cmd) Run(ctx context.Context, cfg *packages.Config, patterns ...string)
 		logger.Printf("%v", err)
 		return nil, fmt.Errorf("package load failed")
 	}
-
 	logger.Printf("analyzing %d packages...\n", len(loadedPkgs))
 
 	r, err := vulncheck.Source(ctx, loadedPkgs, &vulncheck.Config{Client: c.Client, SourceGoVersion: goVersion()})
@@ -236,6 +236,11 @@ func init() {
 			logf("Failed to load packages: %v", err)
 			return err
 		}
+		if n := packages.PrintErrors(pkgs); n > 0 {
+			err := errors.New("failed to load packages due to errors")
+			logf("%v", err)
+			return err
+		}
 		logf("Loaded %d packages and their dependencies", len(pkgs))
 		cli, err := client.NewClient(findGOVULNDB(cfg.Env), client.Options{
 			HTTPCache: govulncheck.DefaultCache(),