simplify anonymous import handling

Anonymous imports were being special-cased and written out separately. They're not that special though, we can just count them as regular imports with the name "_".

This causes them to get grouped together with the other imports like one would expect, and simplifies the generator a bit.

Fixes google#358.

internal/wire/wire.go

@@ -188,7 +188,10 @@ func generateInjectors(g *gen, pkg *packages.Package) (injectorFiles []*ast.File
 
  for _, impt := range f.Imports {
  if impt.Name != nil && impt.Name.Name == "_" {
- g.anonImports[impt.Path.Value] = true
+ g.imports[strings.Trim(impt.Path.Value, `"`)] = importInfo{
+ name: "_",
+ differs: true,
+ }
  }
  }
  }
@@ -241,19 +244,17 @@ type importInfo struct {
 
 // gen is the file-wide generator state.
 type gen struct {
- pkg *packages.Package
- buf bytes.Buffer
- imports map[string]importInfo
- anonImports map[string]bool
- values map[ast.Expr]string
+ pkg *packages.Package
+ buf bytes.Buffer
+ imports map[string]importInfo
+ values map[ast.Expr]string
 }
 
 func newGen(pkg *packages.Package) *gen {
  return &gen{
- pkg: pkg,
- anonImports: make(map[string]bool),
- imports: make(map[string]importInfo),
- values: make(map[ast.Expr]string),
+ pkg: pkg,
+ imports: make(map[string]importInfo),
+ values: make(map[ast.Expr]string),
  }
 }
 
@@ -290,19 +291,6 @@ func (g *gen) frame(tags string) []byte {
  }
  buf.WriteString(")\n\n")
  }
- if len(g.anonImports) > 0 {
- buf.WriteString("import (\n")
- anonImps := make([]string, 0, len(g.anonImports))
- for path := range g.anonImports {
- anonImps = append(anonImps, path)
- }
- sort.Strings(anonImps)
-
- for _, path := range anonImps {
- fmt.Fprintf(&buf, "\t_ %s\n", path)
- }
- buf.WriteString(")\n\n")
- }
  buf.Write(g.buf.Bytes())
  return buf.Bytes()
 }