cmd/go: do not let test vet failures stop reporting of later test results

(This only manifested in test vet failures for packages without tests,
or else we'd probably have seen this sooner.)

Fixes #23047.

Change-Id: I41d09a7780999bbe1951377ffcc811ba86ea5000
Reviewed-on: https://go-review.googlesource.com/83955
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/go_test.go

@@ -5275,6 +5275,10 @@ func TestTestVet(t *testing.T) {
 
 	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
 	tg.run("test", "vetcycle") // must not fail; #22890
+
+	tg.runFail("test", "vetfail/...")
+	tg.grepStderr(`Printf format %d`, "did not diagnose bad Printf")
+	tg.grepStdout(`ok\s+vetfail/p2`, "did not run vetfail/p2")
 }
 
 func TestInstallDeps(t *testing.T) {

src/cmd/go/internal/test/test.go

@@ -1087,7 +1087,7 @@ func builderTest(b *work.Builder, p *load.Package) (buildAction, runAction, prin
 			Func:       c.builderRunTest,
 			Deps:       []*work.Action{buildAction},
 			Package:    p,
-			IgnoreFail: true,
+			IgnoreFail: true, // run (prepare output) even if build failed
 			TryCache:   c.tryCache,
 			Objdir:     testDir,
 		}
@@ -1102,6 +1102,7 @@ func builderTest(b *work.Builder, p *load.Package) (buildAction, runAction, prin
 			Func:       builderCleanTest,
 			Deps:       []*work.Action{runAction},
 			Package:    p,
+			IgnoreFail: true, // clean even if test failed
 			Objdir:     testDir,
 		}
 		printAction = &work.Action{
@@ -1109,6 +1110,7 @@ func builderTest(b *work.Builder, p *load.Package) (buildAction, runAction, prin
 			Func:       builderPrintTest,
 			Deps:       []*work.Action{cleanAction},
 			Package:    p,
+			IgnoreFail: true, // print even if test failed
 		}
 	}
 	if installAction != nil {

src/cmd/go/testdata/src/vetfail/p1/p1.go

+package p1
+
+import "fmt"
+
+func F() {
+	fmt.Printf("%d", "hello") // causes vet error
+}

src/cmd/go/testdata/src/vetfail/p2/p2.go

+package p2
+
+import _ "vetfail/p1"
+
+func F() {
+}

src/cmd/go/testdata/src/vetfail/p2/p2_test.go

+package p2
+
+import "testing"
+
+func TestF(t *testing.T) {
+	F()
+}