cmd/go: when module enabled, `go clean` removes built binary

Now "go clean" can remove binary as expected, when module enabled and the module name isn't  "main" or the name of folder.

Fixes issue #41656

Change-Id: I54b9435ece045e03a12dc230efe84c8dd381a07c
GitHub-Last-Rev: f4ea2d8c76
GitHub-Pull-Request: golang/go#41999
Reviewed-on: https://go-review.googlesource.com/c/go/+/262677
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Trust: Jay Conrod <jayconrod@google.com>
Trust: Bryan C. Mills <bcmills@google.com>

src/cmd/go/internal/clean/clean.go

@@ -276,6 +276,8 @@ func clean(p *load.Package) {
 		allRemove = append(allRemove,
 			elem,
 			elem+".exe",
+			p.DefaultExecName(),
+			p.DefaultExecName()+".exe",
 		)
 	}
 
@@ -283,16 +285,28 @@ func clean(p *load.Package) {
 	allRemove = append(allRemove,
 		elem+".test",
 		elem+".test.exe",
+		p.DefaultExecName()+".test",
+		p.DefaultExecName()+".test.exe",
 	)
 
-	// Remove a potential executable for each .go file in the directory that
+	// Remove a potential executable, test executable for each .go file in the directory that
 	// is not part of the directory's package.
 	for _, dir := range dirs {
 		name := dir.Name()
 		if packageFile[name] {
 			continue
 		}
-		if !dir.IsDir() && strings.HasSuffix(name, ".go") {
+
+		if dir.IsDir() {
+			continue
+		}
+
+		if strings.HasSuffix(name, "_test.go") {
+			base := name[:len(name)-len("_test.go")]
+			allRemove = append(allRemove, base+".test", base+".test.exe")
+		}
+
+		if strings.HasSuffix(name, ".go") {
 			// TODO(adg,rsc): check that this .go file is actually
 			// in "package main", and therefore capable of building
 			// to an executable file.

src/cmd/go/testdata/script/clean_binary.txt

@@ -0,0 +1,78 @@
+# Build something to create the executable, including several cases
+[short] skip
+
+# --------------------- clean executables -------------------------
+
+# case1: test file-named executable 'main'
+env GO111MODULE=on
+
+! exists main$GOEXE
+go build main.go
+exists -exec main$GOEXE
+go clean
+! exists main$GOEXE
+
+# case2: test module-named executable 'a.b.c'
+! exists a.b.c$GOEXE
+go build
+exists -exec a.b.c$GOEXE
+go clean
+! exists a.b.c$GOEXE
+
+# case3: directory-named executable 'src'
+env GO111MODULE=off
+
+! exists src$GOEXE
+go build
+exists -exec src$GOEXE
+go clean
+! exists src$GOEXE
+
+# --------------------- clean test files -------------------------
+
+# case1: test file-named test file
+env GO111MODULE=on
+
+! exists main.test$GOEXE
+go test -c main_test.go
+exists -exec main.test$GOEXE
+go clean
+! exists main.test$GOEXE
+
+# case2: test module-named test file
+! exists a.b.c.test$GOEXE
+go test -c
+exists -exec a.b.c.test$GOEXE
+go clean
+! exists a.b.c.test$GOEXE
+
+# case3: test directory-based test file
+env GO111MODULE=off
+
+! exists src.test$GOEXE
+go test -c
+exists -exec src.test$GOEXE
+go clean
+! exists src.test$GOEXE
+
+-- main.go --
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("hello!")
+}
+
+-- main_test.go --
+package main
+
+import "testing"
+
+func TestSomething(t *testing.T) {
+}
+
+-- go.mod --
+module example.com/a.b.c/v2
+
+go 1.12