fix cgo issue (#104)

Signed-off-by: Loong <[email protected]>

Author: daixiang0

pkg/gci/gci.go

@@ -129,7 +129,7 @@ func LoadFormatGoFile(file io.FileObj, cfg config.Config) (src, dist []byte, err
 	}
 
 	// do not do format if only one import
-	if len(imports) == 1 {
+	if len(imports) <= 1 {
 		return src, src, nil
 	}
 

pkg/gci/internal/testdata/cgo-block-before-import.cfg.yaml

@@ -0,0 +1,4 @@
+sections:
+  - Standard
+  - Default
+  - Prefix(github.com/daixiang0)

pkg/gci/internal/testdata/cgo-block-before-import.in.go

@@ -0,0 +1,15 @@
+package main
+
+// #cgo CFLAGS: -DPNG_DEBUG=1
+// #cgo amd64 386 CFLAGS: -DX86=1
+// #cgo LDFLAGS: -lpng
+// #include <png.h>
+import "C"
+
+import (
+	"fmt"
+
+	"github.com/daixiang0/gci"
+
+	g "github.com/golang"
+)

pkg/gci/internal/testdata/cgo-block-before-import.out.go

@@ -0,0 +1,15 @@
+package main
+
+// #cgo CFLAGS: -DPNG_DEBUG=1
+// #cgo amd64 386 CFLAGS: -DX86=1
+// #cgo LDFLAGS: -lpng
+// #include <png.h>
+import "C"
+
+import (
+	"fmt"
+
+	g "github.com/golang"
+
+	"github.com/daixiang0/gci"
+)

pkg/parse/parse.go

@@ -8,6 +8,8 @@ import (
 	"strings"
 )
 
+const C = "\"C\""
+
 type GciImports struct {
 	// original index of import group, include doc, name, path and comment
 	Start, End int
@@ -79,14 +81,17 @@ func ParseFile(src []byte, filename string) (ImportList, int, int, error) {
 		return nil, 0, 0, NoImportError{}
 	}
 
-	var headEnd int
-	var tailStart int
+	var headEnd, tailStart int
 
 	var data ImportList
 	for i, imp := range f.Imports {
+		if imp.Path.Value == C {
+			continue
+		}
+
 		start, end, name := getImports(imp)
 
-		if i == 0 {
+		if headEnd == 0 {
 			headEnd = start
 		}
 		if i == len(f.Imports)-1 {