imports: fix bug, where unused named import is mistaken for unnamed import.

Fixes #8149.

Change-Id: Ia3d318f70981b2032a71d3fd32eaffba20cfbcbd
Reviewed-on: https://go-review.googlesource.com/13371
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

Author: davidrjenni

imports/fix.go

@@ -89,6 +89,21 @@ func fixImports(fset *token.FileSet, f *ast.File) (added []string, err error) {
 	})
 	ast.Walk(visitor, f)
 
+	// Nil out any unused ImportSpecs, to be removed in following passes
+	unusedImport := map[string]bool{}
+	for pkg, is := range decls {
+		if refs[pkg] == nil && pkg != "_" && pkg != "." {
+			unusedImport[strings.Trim(is.Path.Value, `"`)] = true
+		}
+	}
+	for ipath := range unusedImport {
+		if ipath == "C" {
+			// Don't remove cgo stuff.
+			continue
+		}
+		astutil.DeleteImport(fset, f, ipath)
+	}
+
 	// Search for imports matching potential package references.
 	searches := 0
 	type result struct {
@@ -126,21 +141,6 @@ func fixImports(fset *token.FileSet, f *ast.File) (added []string, err error) {
 		}
 	}
 
-	// Nil out any unused ImportSpecs, to be removed in following passes
-	unusedImport := map[string]bool{}
-	for pkg, is := range decls {
-		if refs[pkg] == nil && pkg != "_" && pkg != "." {
-			unusedImport[strings.Trim(is.Path.Value, `"`)] = true
-		}
-	}
-	for ipath := range unusedImport {
-		if ipath == "C" {
-			// Don't remove cgo stuff.
-			continue
-		}
-		astutil.DeleteImport(fset, f, ipath)
-	}
-
 	return added, nil
 }
 

imports/fix_test.go

@@ -707,6 +707,24 @@ var (
 	_ p.P
 	_ = regexp.Compile
 )
+`,
+	},
+
+	// Unused named import is mistaken for unnamed import
+	// golang.org/issue/8149
+	{
+		name: "issue 8149",
+		in: `package main
+
+import foo "fmt"
+
+func main() { fmt.Println() }
+`,
+		out: `package main
+
+import "fmt"
+
+func main() { fmt.Println() }
 `,
 	},
 }