cmd/go: fix test import dependency bug

Fixes a problem Rob is having with goprotobuf.
Cannot add a test because the same case is more broken
when using ./ imports.  That still needs to be fixed,
and is one aspect of issue 3169.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5725043

src/cmd/go/build.go

@@ -363,7 +363,7 @@ func goFilesPackage(gofiles []string) *Package {
 	pkg.Target = ""
 	pkg.Stale = true
 
-	computeStale([]*Package{pkg})
+	computeStale(pkg)
 	return pkg
 }
 

src/cmd/go/pkg.go

@@ -376,7 +376,7 @@ func packageList(roots []*Package) []*Package {
 			return
 		}
 		seen[p] = true
-		for _, p1 := range p.deps {
+		for _, p1 := range p.imports {
 			walk(p1)
 		}
 		all = append(all, p)
@@ -389,7 +389,7 @@ func packageList(roots []*Package) []*Package {
 
 // computeStale computes the Stale flag in the package dag that starts
 // at the named pkgs (command-line arguments).
-func computeStale(pkgs []*Package) {
+func computeStale(pkgs ...*Package) {
 	topRoot := map[string]bool{}
 	for _, p := range pkgs {
 		topRoot[p.Root] = true
@@ -579,7 +579,7 @@ func packagesAndErrors(args []string) []*Package {
 		pkgs = append(pkgs, loadPackage(arg, &stk))
 	}
 
-	computeStale(pkgs)
+	computeStale(pkgs...)
 
 	return pkgs
 }

src/cmd/go/test.go

@@ -396,6 +396,9 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 		imports = append(imports, p1)
 	}
 	for _, path := range p.XTestImports {
+		if path == p.ImportPath {
+			continue
+		}
 		p1 := loadImport(path, p.Dir, &stk, p.build.XTestImportPos[path])
 		if p1.Error != nil {
 			return nil, nil, nil, p1.Error
@@ -447,6 +450,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 		ptest.imports = append(append([]*Package{}, p.imports...), imports...)
 		ptest.pkgdir = testDir
 		ptest.fake = true
+		ptest.Stale = true
 		ptest.build = new(build.Package)
 		*ptest.build = *p.build
 		m := map[string][]token.Position{}
@@ -457,6 +461,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 			m[k] = append(m[k], v...)
 		}
 		ptest.build.ImportPos = m
+		computeStale(ptest)
 		a := b.action(modeBuild, modeBuild, ptest)
 		a.objdir = testDir + string(filepath.Separator)
 		a.objpkg = ptestObj
@@ -480,7 +485,9 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 			imports: append(ximports, ptest),
 			pkgdir:  testDir,
 			fake:    true,
+			Stale:   true,
 		}
+		computeStale(pxtest)
 		a := b.action(modeBuild, modeBuild, pxtest)
 		a.objdir = testDir + string(filepath.Separator)
 		a.objpkg = buildToolchain.pkgpath(testDir, pxtest)
@@ -489,12 +496,14 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 
 	// Action for building pkg.test.
 	pmain = &Package{
-		Name:    "main",
-		Dir:     testDir,
-		GoFiles: []string{"_testmain.go"},
-		imports: []*Package{ptest},
-		build:   &build.Package{},
-		fake:    true,
+		Name:       "main",
+		Dir:        testDir,
+		GoFiles:    []string{"_testmain.go"},
+		ImportPath: "testmain",
+		imports:    []*Package{ptest},
+		build:      &build.Package{},
+		fake:       true,
+		Stale:      true,
 	}
 	if pxtest != nil {
 		pmain.imports = append(pmain.imports, pxtest)
@@ -511,6 +520,7 @@ func (b *builder) test(p *Package) (buildAction, runAction, printAction *action,
 		return nil, nil, nil, pregexp.Error
 	}
 	pmain.imports = append(pmain.imports, ptesting, pregexp)
+	computeStale(pmain)
 
 	a := b.action(modeBuild, modeBuild, pmain)
 	a.objdir = testDir + string(filepath.Separator)