cmd/go: if -race, don't run coverage on runtime packages

Don't compile the runtime packages with coverage when using the race
detector. The user can, perhaps accidentally, request coverage for the
runtime by using -coverpkg=all. If using the race detector, the
runtime package coverage will call into the race detector before it
has been initialized. This will cause the program to crash
mysteriously on startup.

Fixes #23882

Change-Id: I9a63867a9138797d8b8afb0856ae21079accdb27
Reviewed-on: https://go-review.googlesource.com/94898
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Bonventre <andybons@golang.org>

src/cmd/go/go_test.go

@@ -5771,6 +5771,21 @@ func TestAtomicCoverpkgAll(t *testing.T) {
 	}
 }
 
+// Issue 23882.
+func TestCoverpkgAllRuntime(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+
+	tg.tempFile("src/x/x.go", `package x; import _ "runtime"; func F() {}`)
+	tg.tempFile("src/x/x_test.go", `package x; import "testing"; func TestF(t *testing.T) { F() }`)
+	tg.setenv("GOPATH", tg.path("."))
+	tg.run("test", "-coverpkg=all", "x")
+	if canRace {
+		tg.run("test", "-coverpkg=all", "-race", "x")
+	}
+}
+
 func TestBadCommandLines(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()

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

@@ -674,6 +674,14 @@ func runTest(cmd *base.Command, args []string) {
 				continue
 			}
 
+			// If using the race detector, silently ignore
+			// attempts to run coverage on the runtime
+			// packages. It will cause the race detector
+			// to be invoked before it has been initialized.
+			if cfg.BuildRace && p.Standard && (p.ImportPath == "runtime" || strings.HasPrefix(p.ImportPath, "runtime/internal")) {
+				continue
+			}
+
 			if haveMatch {
 				testCoverPkgs = append(testCoverPkgs, p)
 			}