isCgoImport accounts for back-quoted "C" import

Author: nishanths

format/format.go

@@ -833,13 +833,21 @@ func identEqual(expr ast.Expr, name string) bool {
 //
 //   import "C"
 //
+// or the equivalent:
+//
+//   import `C`
+//
 // Note that parentheses do not affect the result.
 func isCgoImport(decl *ast.GenDecl) bool {
 	if decl.Tok != token.IMPORT || len(decl.Specs) != 1 {
 		return false
 	}
 	spec := decl.Specs[0].(*ast.ImportSpec)
-	return spec.Path.Value == `"C"`
+	v, err := strconv.Unquote(spec.Path.Value)
+	if err != nil {
+		panic(err) // should never error
+	}
+	return v == "C"
 }
 
 // joinStdImports ensures that all standard library imports are together and at

testdata/scripts/cgo.txt

@@ -10,18 +10,36 @@ package p
 import "C"
 import "os"
 
+import `C`
+import "os"
+
 import "C"
 import (
 	"io"
 	"utf8"
 )
 
+import `C`
+import (
+	"io"
+	"utf8"
+)
+
 -- foo.go.golden --
 package p
 
 import "C"
 import "os"
 
+import "C"
+import "os"
+
+import "C"
+import (
+	"io"
+	"utf8"
+)
+
 import "C"
 import (
 	"io"