cmd/go: add import config debugging flag

Change-Id: I11d83c8841f3de4ed4d9d014dec65d6f20464b11
Reviewed-on: https://go-review.googlesource.com/78396
Reviewed-by: David Crawshaw <crawshaw@golang.org>

diff --git a/src/cmd/go/internal/load/icfg.go b/src/cmd/go/internal/load/icfg.go
new file mode 100644 (file)
index 0000000..0b346df
--- /dev/null
+++ b/src/cmd/go/internal/load/icfg.go
@@ -0,0 +1,75 @@
+// 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 load
+
+import (
+       "bytes"
+       "encoding/json"
+       "errors"
+       "io/ioutil"
+)
+
+// DebugDeprecatedImportcfg is installed as the undocumented -debug-deprecated-importcfg build flag.
+// It is useful for debugging subtle problems in the go command logic but not something
+// we want users to depend on. The hope is that the "deprecated" will make that clear.
+// We intend to remove this flag in Go 1.11.
+var DebugDeprecatedImportcfg debugDeprecatedImportcfgFlag
+
+type debugDeprecatedImportcfgFlag struct {
+       enabled bool
+       pkgs    map[string]*debugDeprecatedImportcfgPkg
+}
+
+type debugDeprecatedImportcfgPkg struct {
+       Dir    string
+       Import map[string]string
+}
+
+var (
+       debugDeprecatedImportcfgMagic = []byte("# debug-deprecated-importcfg\n")
+       errImportcfgSyntax            = errors.New("malformed syntax")
+)
+
+func (f *debugDeprecatedImportcfgFlag) String() string { return "" }
+
+func (f *debugDeprecatedImportcfgFlag) Set(x string) error {
+       if x == "" {
+               *f = debugDeprecatedImportcfgFlag{}
+               return nil
+       }
+       data, err := ioutil.ReadFile(x)
+       if err != nil {
+               return err
+       }
+
+       if !bytes.HasPrefix(data, debugDeprecatedImportcfgMagic) {
+               return errImportcfgSyntax
+       }
+       data = data[len(debugDeprecatedImportcfgMagic):]
+
+       f.pkgs = nil
+       if err := json.Unmarshal(data, &f.pkgs); err != nil {
+               return errImportcfgSyntax
+       }
+       f.enabled = true
+       return nil
+}
+
+func (f *debugDeprecatedImportcfgFlag) lookup(parent *Package, path string) (dir, newPath string) {
+       if parent == nil {
+               if p1 := f.pkgs[path]; p1 != nil {
+                       return p1.Dir, path
+               }
+               return "", ""
+       }
+       if p1 := f.pkgs[parent.ImportPath]; p1 != nil {
+               if newPath := p1.Import[path]; newPath != "" {
+                       if p2 := f.pkgs[newPath]; p2 != nil {
+                               return p2.Dir, newPath
+                       }
+               }
+       }
+       return "", ""
+}

diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 15ef95312b086c35d4071437a5acce1c3e403b85..2b3d7fd0e1a3c521401794a0ae4007d083719d6f 100644 (file)
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -383,8 +383,14 @@ func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPo
        importPath := path
        origPath := path
        isLocal := build.IsLocalImport(path)
+       var debugDeprecatedImportcfgDir string
        if isLocal {
                importPath = dirToImportPath(filepath.Join(srcDir, path))
+       } else if DebugDeprecatedImportcfg.enabled {
+               if d, i := DebugDeprecatedImportcfg.lookup(parent, path); d != "" {
+                       debugDeprecatedImportcfgDir = d
+                       importPath = i
+               }
        } else if mode&UseVendor != 0 {
                // We do our own vendor resolution, because we want to
                // find out the key to use in packageCache without the
@@ -406,17 +412,23 @@ func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPo
                // Load package.
                // Import always returns bp != nil, even if an error occurs,
                // in order to return partial information.
-               buildMode := build.ImportComment
-               if mode&UseVendor == 0 || path != origPath {
-                       // Not vendoring, or we already found the vendored path.
-                       buildMode |= build.IgnoreVendor
+               var bp *build.Package
+               var err error
+               if debugDeprecatedImportcfgDir != "" {
+                       bp, err = cfg.BuildContext.ImportDir(debugDeprecatedImportcfgDir, 0)
+               } else {
+                       buildMode := build.ImportComment
+                       if mode&UseVendor == 0 || path != origPath {
+                               // Not vendoring, or we already found the vendored path.
+                               buildMode |= build.IgnoreVendor
+                       }
+                       bp, err = cfg.BuildContext.Import(path, srcDir, buildMode)
                }
-               bp, err := cfg.BuildContext.Import(path, srcDir, buildMode)
                bp.ImportPath = importPath
                if cfg.GOBIN != "" {
                        bp.BinDir = cfg.GOBIN
                }
-               if err == nil && !isLocal && bp.ImportComment != "" && bp.ImportComment != path &&
+               if debugDeprecatedImportcfgDir == "" && err == nil && !isLocal && bp.ImportComment != "" && bp.ImportComment != path &&
                        !strings.Contains(path, "/vendor/") && !strings.HasPrefix(path, "vendor/") {
                        err = fmt.Errorf("code in directory %s expects import %q", bp.Dir, bp.ImportComment)
                }
@@ -425,7 +437,7 @@ func LoadImport(path, srcDir string, parent *Package, stk *ImportStack, importPo
                        p = setErrorPos(p, importPos)
                }
 
-               if origPath != cleanImport(origPath) {
+               if debugDeprecatedImportcfgDir == "" && origPath != cleanImport(origPath) {
                        p.Error = &PackageError{
                                ImportStack: stk.Copy(),
                                Err:         fmt.Sprintf("non-canonical import path: %q should be %q", origPath, pathpkg.Clean(origPath)),

diff --git a/src/cmd/go/internal/work/build.go b/src/cmd/go/internal/work/build.go
index fdd6ff6a6f649b6b74ad281f98cf4cdd302b6a52..6ae2ca35cf35540c158f66f8e6712888726ff545 100644 (file)
--- a/src/cmd/go/internal/work/build.go
+++ b/src/cmd/go/internal/work/build.go
@@ -229,6 +229,7 @@ func AddBuildFlags(cmd *base.Command) {
 
        // Undocumented, unstable debugging flags.
        cmd.Flag.StringVar(&cfg.DebugActiongraph, "debug-actiongraph", "", "")
+       cmd.Flag.Var(&load.DebugDeprecatedImportcfg, "debug-deprecated-importcfg", "")
 }
 
 // fileExtSplit expects a filename and returns the name