cmd/dist: refactor rtPreFunc to print skips in only one place

Currently, all uses of rtPreFunc are to print a message and skip a
test. When we move to JSON, the logic to just "print a message" is
going to be more complicated, so refactor this so the function returns
the skip message and we print it in just one place. We also rename the
option to rtSkipFunc to better represent what we use it for.

For #37486.

Change-Id: Ibd537064fa646a956a1c0f85a5d8c6febd098dde
Reviewed-on: https://go-review.googlesource.com/c/go/+/495856
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

1 files changed, 22 insertions, 21 deletions

diff --git a/src/cmd/dist/test.go b/src/cmd/dist/test.go
index d92388c444..4b33933459 100644
--- a/src/cmd/dist/test.go
+++ b/src/cmd/dist/test.go
@@ -912,13 +912,13 @@ type registerTestOpt interface {
 	isRegisterTestOpt()
 }
 
-// rtPreFunc is a registerTest option that runs a pre function before running
-// the test.
-type rtPreFunc struct {
-	pre func(*distTest) bool // Return false to skip the test
+// rtSkipFunc is a registerTest option that runs a skip check function before
+// running the test.
+type rtSkipFunc struct {
+	skip func(*distTest) (string, bool) // Return message, true to skip the test
 }
 
-func (rtPreFunc) isRegisterTestOpt() {}
+func (rtSkipFunc) isRegisterTestOpt() {}
 
 // registerTest registers a test that runs the given goTest.
 //
@@ -937,16 +937,20 @@ func (t *tester) registerTest(name, heading string, test *goTest, opts ...regist
 		}
 		t.variantNames[variantName] = true
 	}
-	var preFunc func(*distTest) bool
+	var skipFunc func(*distTest) (string, bool)
 	for _, opt := range opts {
 		switch opt := opt.(type) {
-		case rtPreFunc:
-			preFunc = opt.pre
+		case rtSkipFunc:
+			skipFunc = opt.skip
 		}
 	}
 	t.addTest(name, heading, func(dt *distTest) error {
-		if preFunc != nil && !preFunc(dt) {
-			return nil
+		if skipFunc != nil {
+			msg, skip := skipFunc(dt)
+			if skip {
+				fmt.Println(msg)
+				return nil
+			}
 		}
 		w := &work{dt: dt}
 		w.cmd = test.bgCommand(t, &w.out, &w.out)
@@ -1147,13 +1151,12 @@ func (t *tester) registerCgoTests(heading string) {
 			// -fPIC fundamentally.)
 		default:
 			// Check for static linking support
-			var staticCheck rtPreFunc
+			var staticCheck rtSkipFunc
 			ccName := compilerEnvLookup("CC", defaultcc, goos, goarch)
 			cc, err := exec.LookPath(ccName)
 			if err != nil {
-				staticCheck.pre = func(*distTest) bool {
-					fmt.Printf("$CC (%q) not found, skip cgo static linking test.\n", ccName)
-					return false
+				staticCheck.skip = func(*distTest) (string, bool) {
+					return fmt.Sprintf("$CC (%q) not found, skip cgo static linking test.", ccName), true
 				}
 			} else {
 				cmd := t.dirCmd("src/cmd/cgo/internal/test", cc, "-xc", "-o", "/dev/null", "-static", "-")
@@ -1161,9 +1164,8 @@ func (t *tester) registerCgoTests(heading string) {
 				cmd.Stdout, cmd.Stderr = nil, nil // Discard output
 				if err := cmd.Run(); err != nil {
 					// Skip these tests
-					staticCheck.pre = func(*distTest) bool {
-						fmt.Println("No support for static linking found (lacks libc.a?), skip cgo static linking test.")
-						return false
+					staticCheck.skip = func(*distTest) (string, bool) {
+						return "No support for static linking found (lacks libc.a?), skip cgo static linking test.", true
 					}
 				}
 			}
@@ -1172,10 +1174,9 @@ func (t *tester) registerCgoTests(heading string) {
 			// a C linker warning on Linux.
 			// in function `bio_ip_and_port_to_socket_and_addr':
 			// warning: Using 'getaddrinfo' in statically linked applications requires at runtime the shared libraries from the glibc version used for linking
-			if staticCheck.pre == nil && goos == "linux" && strings.Contains(goexperiment, "boringcrypto") {
-				staticCheck.pre = func(*distTest) bool {
-					fmt.Println("skipping static linking check on Linux when using boringcrypto to avoid C linker warning about getaddrinfo")
-					return false
+			if staticCheck.skip == nil && goos == "linux" && strings.Contains(goexperiment, "boringcrypto") {
+				staticCheck.skip = func(*distTest) (string, bool) {
+					return "skipping static linking check on Linux when using boringcrypto to avoid C linker warning about getaddrinfo", true
 				}
 			}