1 files changed, 265 insertions, 0 deletions
diff --git a/src/go/internal/srcimporter/srcimporter.go b/src/go/internal/srcimporter/srcimporter.go
new file mode 100644
index 0000000..438ae0f
--- /dev/null
+++ b/src/go/internal/srcimporter/srcimporter.go
@@ -0,0 +1,265 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package srcimporter implements importing directly
+// from source files rather than installed packages.
+package srcimporter // import "go/internal/srcimporter"
+
+import (
+	"fmt"
+	"go/ast"
+	"go/build"
+	"go/parser"
+	"go/token"
+	"go/types"
+	exec "internal/execabs"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	_ "unsafe" // for go:linkname
+)
+
+// An Importer provides the context for importing packages from source code.
+type Importer struct {
+	ctxt     *build.Context
+	fset     *token.FileSet
+	sizes    types.Sizes
+	packages map[string]*types.Package
+}
+
+// NewImporter returns a new Importer for the given context, file set, and map
+// of packages. The context is used to resolve import paths to package paths,
+// and identifying the files belonging to the package. If the context provides
+// non-nil file system functions, they are used instead of the regular package
+// os functions. The file set is used to track position information of package
+// files; and imported packages are added to the packages map.
+func New(ctxt *build.Context, fset *token.FileSet, packages map[string]*types.Package) *Importer {
+	return &Importer{
+		ctxt:     ctxt,
+		fset:     fset,
+		sizes:    types.SizesFor(ctxt.Compiler, ctxt.GOARCH), // uses go/types default if GOARCH not found
+		packages: packages,
+	}
+}
+
+// Importing is a sentinel taking the place in Importer.packages
+// for a package that is in the process of being imported.
+var importing types.Package
+
+// Import(path) is a shortcut for ImportFrom(path, ".", 0).
+func (p *Importer) Import(path string) (*types.Package, error) {
+	return p.ImportFrom(path, ".", 0) // use "." rather than "" (see issue #24441)
+}
+
+// ImportFrom imports the package with the given import path resolved from the given srcDir,
+// adds the new package to the set of packages maintained by the importer, and returns the
+// package. Package path resolution and file system operations are controlled by the context
+// maintained with the importer. The import mode must be zero but is otherwise ignored.
+// Packages that are not comprised entirely of pure Go files may fail to import because the
+// type checker may not be able to determine all exported entities (e.g. due to cgo dependencies).
+func (p *Importer) ImportFrom(path, srcDir string, mode types.ImportMode) (*types.Package, error) {
+	if mode != 0 {
+		panic("non-zero import mode")
+	}
+
+	if abs, err := p.absPath(srcDir); err == nil { // see issue #14282
+		srcDir = abs
+	}
+	bp, err := p.ctxt.Import(path, srcDir, 0)
+	if err != nil {
+		return nil, err // err may be *build.NoGoError - return as is
+	}
+
+	// package unsafe is known to the type checker
+	if bp.ImportPath == "unsafe" {
+		return types.Unsafe, nil
+	}
+
+	// no need to re-import if the package was imported completely before
+	pkg := p.packages[bp.ImportPath]
+	if pkg != nil {
+		if pkg == &importing {
+			return nil, fmt.Errorf("import cycle through package %q", bp.ImportPath)
+		}
+		if !pkg.Complete() {
+			// Package exists but is not complete - we cannot handle this
+			// at the moment since the source importer replaces the package
+			// wholesale rather than augmenting it (see #19337 for details).
+			// Return incomplete package with error (see #16088).
+			return pkg, fmt.Errorf("reimported partially imported package %q", bp.ImportPath)
+		}
+		return pkg, nil
+	}
+
+	p.packages[bp.ImportPath] = &importing
+	defer func() {
+		// clean up in case of error
+		// TODO(gri) Eventually we may want to leave a (possibly empty)
+		// package in the map in all cases (and use that package to
+		// identify cycles). See also issue 16088.
+		if p.packages[bp.ImportPath] == &importing {
+			p.packages[bp.ImportPath] = nil
+		}
+	}()
+
+	var filenames []string
+	filenames = append(filenames, bp.GoFiles...)
+	filenames = append(filenames, bp.CgoFiles...)
+
+	files, err := p.parseFiles(bp.Dir, filenames)
+	if err != nil {
+		return nil, err
+	}
+
+	// type-check package files
+	var firstHardErr error
+	conf := types.Config{
+		IgnoreFuncBodies: true,
+		// continue type-checking after the first error
+		Error: func(err error) {
+			if firstHardErr == nil && !err.(types.Error).Soft {
+				firstHardErr = err
+			}
+		},
+		Importer: p,
+		Sizes:    p.sizes,
+	}
+	if len(bp.CgoFiles) > 0 {
+		if p.ctxt.OpenFile != nil {
+			// cgo, gcc, pkg-config, etc. do not support
+			// build.Context's VFS.
+			conf.FakeImportC = true
+		} else {
+			setUsesCgo(&conf)
+			file, err := p.cgo(bp)
+			if err != nil {
+				return nil, err
+			}
+			files = append(files, file)
+		}
+	}
+
+	pkg, err = conf.Check(bp.ImportPath, p.fset, files, nil)
+	if err != nil {
+		// If there was a hard error it is possibly unsafe
+		// to use the package as it may not be fully populated.
+		// Do not return it (see also #20837, #20855).
+		if firstHardErr != nil {
+			pkg = nil
+			err = firstHardErr // give preference to first hard error over any soft error
+		}
+		return pkg, fmt.Errorf("type-checking package %q failed (%v)", bp.ImportPath, err)
+	}
+	if firstHardErr != nil {
+		// this can only happen if we have a bug in go/types
+		panic("package is not safe yet no error was returned")
+	}
+
+	p.packages[bp.ImportPath] = pkg
+	return pkg, nil
+}
+
+func (p *Importer) parseFiles(dir string, filenames []string) ([]*ast.File, error) {
+	// use build.Context's OpenFile if there is one
+	open := p.ctxt.OpenFile
+	if open == nil {
+		open = func(name string) (io.ReadCloser, error) { return os.Open(name) }
+	}
+
+	files := make([]*ast.File, len(filenames))
+	errors := make([]error, len(filenames))
+
+	var wg sync.WaitGroup
+	wg.Add(len(filenames))
+	for i, filename := range filenames {
+		go func(i int, filepath string) {
+			defer wg.Done()
+			src, err := open(filepath)
+			if err != nil {
+				errors[i] = err // open provides operation and filename in error
+				return
+			}
+			files[i], errors[i] = parser.ParseFile(p.fset, filepath, src, 0)
+			src.Close() // ignore Close error - parsing may have succeeded which is all we need
+		}(i, p.joinPath(dir, filename))
+	}
+	wg.Wait()
+
+	// if there are errors, return the first one for deterministic results
+	for _, err := range errors {
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return files, nil
+}
+
+func (p *Importer) cgo(bp *build.Package) (*ast.File, error) {
+	tmpdir, err := os.MkdirTemp("", "srcimporter")
+	if err != nil {
+		return nil, err
+	}
+	defer os.RemoveAll(tmpdir)
+
+	args := []string{"go", "tool", "cgo", "-objdir", tmpdir}
+	if bp.Goroot {
+		switch bp.ImportPath {
+		case "runtime/cgo":
+			args = append(args, "-import_runtime_cgo=false", "-import_syscall=false")
+		case "runtime/race":
+			args = append(args, "-import_syscall=false")
+		}
+	}
+	args = append(args, "--")
+	args = append(args, strings.Fields(os.Getenv("CGO_CPPFLAGS"))...)
+	args = append(args, bp.CgoCPPFLAGS...)
+	if len(bp.CgoPkgConfig) > 0 {
+		cmd := exec.Command("pkg-config", append([]string{"--cflags"}, bp.CgoPkgConfig...)...)
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			return nil, err
+		}
+		args = append(args, strings.Fields(string(out))...)
+	}
+	args = append(args, "-I", tmpdir)
+	args = append(args, strings.Fields(os.Getenv("CGO_CFLAGS"))...)
+	args = append(args, bp.CgoCFLAGS...)
+	args = append(args, bp.CgoFiles...)
+
+	cmd := exec.Command(args[0], args[1:]...)
+	cmd.Dir = bp.Dir
+	if err := cmd.Run(); err != nil {
+		return nil, err
+	}
+
+	return parser.ParseFile(p.fset, filepath.Join(tmpdir, "_cgo_gotypes.go"), nil, 0)
+}
+
+// context-controlled file system operations
+
+func (p *Importer) absPath(path string) (string, error) {
+	// TODO(gri) This should be using p.ctxt.AbsPath which doesn't
+	// exist but probably should. See also issue #14282.
+	return filepath.Abs(path)
+}
+
+func (p *Importer) isAbsPath(path string) bool {
+	if f := p.ctxt.IsAbsPath; f != nil {
+		return f(path)
+	}
+	return filepath.IsAbs(path)
+}
+
+func (p *Importer) joinPath(elem ...string) string {
+	if f := p.ctxt.JoinPath; f != nil {
+		return f(elem...)
+	}
+	return filepath.Join(elem...)
+}
+
+//go:linkname setUsesCgo go/types.srcimporter_setUsesCgo
+func setUsesCgo(conf *types.Config)