go/doc: fix identifier blank import handling for examples

Replacement CL for 6813061; thanks to minux for prototyping.

Fixes #4300.

R=minux.ma
CC=golang-dev
https://golang.org/cl/6782082

diff --git a/src/cmd/godoc/godoc.go b/src/cmd/godoc/godoc.go
index b72aad56c0843fef93b75cadbede88ac21146e29..57ef9f37782ef391afa49f8a1ac6b415425d0b89 100644 (file)
--- a/src/cmd/godoc/godoc.go
+++ b/src/cmd/godoc/godoc.go
@@ -356,6 +356,7 @@ func example_htmlFunc(funcName string, examples []*doc.Example, fset *token.File
                // (use tabs, no comment highlight, etc).
                play := ""
                if eg.Play != nil && *showPlayground {
+                       ast.SortImports(fset, eg.Play)
                        var buf bytes.Buffer
                        err := (&printer.Config{Mode: printer.TabIndent, Tabwidth: 8}).Fprint(&buf, fset, eg.Play)
                        if err != nil {

diff --git a/src/pkg/go/doc/example.go b/src/pkg/go/doc/example.go
index 5c51ecef34fbc96dc3469909baa8b6a0852253a9..e5752bb15a16ee22124f6a9bd37cd0f36c82994d 100644 (file)
--- a/src/pkg/go/doc/example.go
+++ b/src/pkg/go/doc/example.go
@@ -145,8 +145,9 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
 
        // Use unresolved identifiers to determine the imports used by this
        // example. The heuristic assumes package names match base import
-       // paths. (Should be good enough most of the time.)
-       imports := make(map[string]string) // [name]path
+       // paths for imports w/o renames (should be good enough most of the time).
+       namedImports := make(map[string]string) // [name]path
+       var blankImports []ast.Spec             // _ imports
        for _, s := range file.Imports {
                p, err := strconv.Unquote(s.Path.Value)
                if err != nil {
@@ -154,14 +155,18 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
                }
                n := path.Base(p)
                if s.Name != nil {
-                       if s.Name.Name == "." {
+                       n = s.Name.Name
+                       switch n {
+                       case "_":
+                               blankImports = append(blankImports, s)
+                               continue
+                       case ".":
                                // We can't resolve dot imports (yet).
                                return nil
                        }
-                       n = s.Name.Name
                }
                if unresolved[n] {
-                       imports[n] = p
+                       namedImports[n] = p
                        delete(unresolved, n)
                }
        }
@@ -172,13 +177,19 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
                return nil
        }
 
-       // Filter out comments that are outside the function body.
+       // Include documentation belonging to blank imports.
        var comments []*ast.CommentGroup
+       for _, s := range blankImports {
+               if c := s.(*ast.ImportSpec).Doc; c != nil {
+                       comments = append(comments, c)
+               }
+       }
+
+       // Include comments that are inside the function body.
        for _, c := range file.Comments {
-               if c.Pos() < body.Pos() || c.Pos() >= body.End() {
-                       continue
+               if body.Pos() <= c.Pos() && c.End() <= body.End() {
+                       comments = append(comments, c)
                }
-               comments = append(comments, c)
        }
 
        // Strip "Output:" commment and adjust body end position.
@@ -190,13 +201,14 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
                Lparen: 1, // Need non-zero Lparen and Rparen so that printer
                Rparen: 1, // treats this as a factored import.
        }
-       for n, p := range imports {
+       for n, p := range namedImports {
                s := &ast.ImportSpec{Path: &ast.BasicLit{Value: strconv.Quote(p)}}
                if path.Base(p) != n {
                        s.Name = ast.NewIdent(n)
                }
                importDecl.Specs = append(importDecl.Specs, s)
        }
+       importDecl.Specs = append(importDecl.Specs, blankImports...)
 
        // Synthesize main function.
        funcDecl := &ast.FuncDecl{
@@ -213,7 +225,7 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
        }
 }
 
-// playExample takes a whole file example and synthesizes a new *ast.File
+// playExampleFile takes a whole file example and synthesizes a new *ast.File
 // such that the example is function main in package main.
 func playExampleFile(file *ast.File) *ast.File {
        // Strip copyright comment if present.