packages: extract importpath from proto go_package options

packages/fileinfo.go

@@ -40,7 +40,6 @@ type fileInfo struct {
 	// This may be read from a package comment (in Go) or a go_package
 	// option (in proto). This field is empty for files that don't specify
 	// an import path.
-	// TODO(#874): extract from Go files
 	importPath string
 
 	// category is the type of file, based on extension.

packages/fileinfo_go.go

@@ -37,6 +37,7 @@ import (
 // If the file can't be read, an error will be logged, and partial information
 // will be returned.
 // This function is intended to match go/build.Context.Import.
+// TODD(#53): extract canonical import path
 func goFileInfo(c *config.Config, dir, rel, name string) fileInfo {
 	info := fileNameInfo(dir, rel, name)
 	fset := token.NewFileSet()

packages/fileinfo_go_test.go

@@ -357,12 +357,16 @@ import "C"
 	if err := ioutil.WriteFile(goFile, content, 0644); err != nil {
 		t.Fatal(err)
 	}
-	c := &config.Config{RepoRoot: repo}
+	c := &config.Config{
+		RepoRoot: repo,
+		GoPrefix: "example.com/repo",
+	}
 	got := buildPackage(c, sub, "sub", []string{"sub.go"}, nil, nil, false)
 	want := &Package{
-		Name: "sub",
-		Dir:  sub,
-		Rel:  "sub",
+		Name:       "sub",
+		Dir:        sub,
+		Rel:        "sub",
+		ImportPath: "example.com/repo/sub",
 		Library: GoTarget{
 			Sources: PlatformStrings{
 				Generic: []string{"sub.go"},

packages/package.go

@@ -41,6 +41,9 @@ type Package struct {
 	// Components in Rel are separated with slashes.
 	Rel string
 
+	// ImportPath is the string used to import this package in Go.
+	ImportPath string
+
 	Library, Binary, Test, XTest GoTarget
 	Proto                        ProtoTarget
 
@@ -95,18 +98,6 @@ func (p *Package) IsCommand() bool {
 	return p.Name == "main"
 }
 
-// ImportPath returns the inferred Go import path for this package.
-// TODO(jayconrod): extract canonical import paths from comments on
-// package statements.
-func (p *Package) ImportPath(c *config.Config) string {
-	if p.Rel == c.GoPrefixRel {
-		return c.GoPrefix
-	} else {
-		fromPrefixRel := strings.TrimPrefix(p.Rel, c.GoPrefixRel+"/")
-		return path.Join(c.GoPrefix, fromPrefixRel)
-	}
-}
-
 func (t *GoTarget) HasGo() bool {
 	return t.Sources.HasGo()
 }
@@ -158,6 +149,7 @@ type packageBuilder struct {
 	library, binary, test, xtest goTargetBuilder
 	proto                        protoTargetBuilder
 	hasTestdata                  bool
+	importPath, importPathFile   string
 }
 
 type goTargetBuilder struct {
@@ -224,6 +216,15 @@ func (pb *packageBuilder) addFile(c *config.Config, info fileInfo, cgo bool) err
 		pb.proto.hasPbGo = true
 	}
 
+	if info.importPath != "" {
+		if pb.importPath == "" {
+			pb.importPath = info.importPath
+			pb.importPathFile = info.path
+		} else if pb.importPath != info.importPath {
+			return fmt.Errorf("found import comments %q (%s) and %q (%s)", pb.importPath, pb.importPathFile, info.importPath, info.path)
+		}
+	}
+
 	return nil
 }
 
@@ -256,11 +257,28 @@ func (pb *packageBuilder) firstGoFile() string {
 	return ""
 }
 
+func (pb *packageBuilder) inferImportPath(c *config.Config) error {
+	if pb.importPath != "" {
+		log.Panic("importPath already set")
+	}
+	if pb.rel == c.GoPrefixRel {
+		if c.GoPrefix == "" {
+			return fmt.Errorf("in directory %q, prefix is empty, so importpath would be empty for rules. Set a prefix with a '# gazelle:prefix' comment or with -go_prefix on the command line.", pb.dir)
+		}
+		pb.importPath = c.GoPrefix
+	} else {
+		fromPrefixRel := strings.TrimPrefix(pb.rel, c.GoPrefixRel+"/")
+		pb.importPath = path.Join(c.GoPrefix, fromPrefixRel)
+	}
+	return nil
+}
+
 func (pb *packageBuilder) build() *Package {
 	return &Package{
 		Name:        pb.name,
 		Dir:         pb.dir,
 		Rel:         pb.rel,
+		ImportPath:  pb.importPath,
 		Library:     pb.library.build(),
 		Binary:      pb.binary.build(),
 		Test:        pb.test.build(),

packages/walk.go

@@ -265,14 +265,15 @@ func buildPackage(c *config.Config, dir, rel string, pkgFiles, otherFiles, genFi
 	// or I/O errors. We should keep the file in the srcs list and let the
 	// compiler deal with the error.
 	for _, info := range pkgFilesWithUnknownPackage {
-		pkg.addFile(c, info, cgo)
+		if err := pkg.addFile(c, info, cgo); err != nil {
+			log.Print(err)
+		}
 	}
 
 	// Process the other static files.
 	for _, file := range otherFiles {
 		info := otherFileInfo(dir, rel, file)
-		err = pkg.addFile(c, info, cgo)
-		if err != nil {
+		if err := pkg.addFile(c, info, cgo); err != nil {
 			log.Print(err)
 		}
 	}
@@ -292,12 +293,17 @@ func buildPackage(c *config.Config, dir, rel string, pkgFiles, otherFiles, genFi
 			continue
 		}
 		info := fileNameInfo(dir, rel, f)
-		err := pkg.addFile(c, info, cgo)
-		if err != nil {
+		if err := pkg.addFile(c, info, cgo); err != nil {
 			log.Print(err)
 		}
 	}
 
+	if pkg.importPath == "" {
+		if err := pkg.inferImportPath(c); err != nil {
+			log.Print(err)
+			return nil
+		}
+	}
 	return pkg.build()
 }