misc/swig: restructure as a driver

Currently, the misc/swig tests directly use Swig and C++ and will fail
to build if either Swig or a C++ compiler are not present. Typically,
we hide this fact from users because dist test itself checks for Swig
and a C++ compiler before even attempting to run this test, though
users will see this is they try to go test ./... from misc.

However, we're about to move the misc/swig tests into the cmd module,
where they will be much more visible and much more likely to run
unintentionally. To prevent build errors, this CL restructures these
tests into a single pure Go test plus two test packages hidden in
testdata. This is relatively easy to do for this test because there
are only four test cases total. The pure Go test can check for the
necessary build tools before trying to build and run the tests in
testdata. This also gives us the opportunity to move the LTO variant
of these tests out of dist and into the test itself, simplifying dist.

For #37486.

Change-Id: Ibda089b4069e36866cb31867a7006c790be2d8b1
Reviewed-on: https://go-review.googlesource.com/c/go/+/493599
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>

1 files changed, 2 insertions, 94 deletions

diff --git a/src/cmd/dist/test.go b/src/cmd/dist/test.go
index 2e0072f44f..95c27ce327 100644
--- a/src/cmd/dist/test.go
+++ b/src/cmd/dist/test.go
@@ -870,21 +870,8 @@ func (t *tester) registerTests() {
 		if goos != "android" {
 			t.registerTest("cgo_testfortran", "", &goTest{dir: "cmd/cgo/internal/testfortran", timeout: 5 * time.Minute}, rtHostTest{})
 		}
-		if t.hasSwig() && goos != "android" {
-			t.registerTest("swig_stdio", "", &goTest{dir: "../misc/swig/stdio"})
-			if t.hasCxx() {
-				t.registerTest("swig_callback", "", &goTest{dir: "../misc/swig/callback"})
-				const cflags = "-flto -Wno-lto-type-mismatch -Wno-unknown-warning-option"
-				t.registerTest("swig_callback_lto", "",
-					&goTest{
-						dir: "../misc/swig/callback",
-						env: []string{
-							"CGO_CFLAGS=" + cflags,
-							"CGO_CXXFLAGS=" + cflags,
-							"CGO_LDFLAGS=" + cflags,
-						},
-					})
-			}
+		if goos != "android" {
+			t.registerTest("swig", "", &goTest{dir: "../misc/swig"})
 		}
 	}
 	if t.cgoEnabled {
@@ -1412,85 +1399,6 @@ func (t *tester) hasBash() bool {
 	return true
 }
 
-func (t *tester) hasCxx() bool {
-	cxx, _ := exec.LookPath(compilerEnvLookup("CXX", defaultcxx, goos, goarch))
-	return cxx != ""
-}
-
-func (t *tester) hasSwig() bool {
-	swig, err := exec.LookPath("swig")
-	if err != nil {
-		return false
-	}
-
-	// Check that swig was installed with Go support by checking
-	// that a go directory exists inside the swiglib directory.
-	// See https://golang.org/issue/23469.
-	output, err := exec.Command(swig, "-go", "-swiglib").Output()
-	if err != nil {
-		return false
-	}
-	swigDir := strings.TrimSpace(string(output))
-
-	_, err = os.Stat(filepath.Join(swigDir, "go"))
-	if err != nil {
-		return false
-	}
-
-	// Check that swig has a new enough version.
-	// See https://golang.org/issue/22858.
-	out, err := exec.Command(swig, "-version").CombinedOutput()
-	if err != nil {
-		return false
-	}
-
-	re := regexp.MustCompile(`[vV]ersion +(\d+)([.]\d+)?([.]\d+)?`)
-	matches := re.FindSubmatch(out)
-	if matches == nil {
-		// Can't find version number; hope for the best.
-		return true
-	}
-
-	major, err := strconv.Atoi(string(matches[1]))
-	if err != nil {
-		// Can't find version number; hope for the best.
-		return true
-	}
-	if major < 3 {
-		return false
-	}
-	if major > 3 {
-		// 4.0 or later
-		return true
-	}
-
-	// We have SWIG version 3.x.
-	if len(matches[2]) > 0 {
-		minor, err := strconv.Atoi(string(matches[2][1:]))
-		if err != nil {
-			return true
-		}
-		if minor > 0 {
-			// 3.1 or later
-			return true
-		}
-	}
-
-	// We have SWIG version 3.0.x.
-	if len(matches[3]) > 0 {
-		patch, err := strconv.Atoi(string(matches[3][1:]))
-		if err != nil {
-			return true
-		}
-		if patch < 6 {
-			// Before 3.0.6.
-			return false
-		}
-	}
-
-	return true
-}
-
 // hasParallelism is a copy of the function
 // internal/testenv.HasParallelism, which can't be used here
 // because cmd/dist can not import internal packages during bootstrap.