Fix removing named imports and fix removing imports with init() methods

main.go

@@ -1493,9 +1493,7 @@ func (tf *transformer) removeUnnecessaryImports(file *ast.File) {
 			continue
 		}
 
-		if !astutil.DeleteImport(fset, file, path) {
-			panic(fmt.Sprintf("cannot delete unused import: %q", path))
-		}
+		imp.Name = ast.NewIdent("_")
 	}
 }
 

testdata/mod/gopkg.in_garbletestconst.v2_v2.999.0.txt

@@ -0,0 +1,32 @@
+module gopkg.in/garbletestconst.v2@v2.999.0
+
+-- .mod --
+module gopkg.in/garbletestconst.v2
+
+go 1.17
+
+-- .info --
+{"Version":"v2.999.0","Time":"2020-11-17T15:46:20Z"}
+-- go.mod --
+module gopkg.in/garbletestconst.v2
+
+go 1.17
+-- consts.go --
+package garbletestconst
+
+import (
+	"database/sql"
+	"database/sql/driver"
+)
+
+const StrConst = "42"
+
+func init() {
+	sql.Register("dummy", dummy{})
+}
+
+type dummy struct{}
+
+func (dummy) Open(string) (driver.Conn, error) {
+	panic("not implemented")
+}

testdata/scripts/imports.txt

@@ -49,6 +49,7 @@ go 1.18
 
 require (
 	gopkg.in/garbletest.v2 v2.999.0
+	gopkg.in/garbletestconst.v2 v2.999.0
 	rsc.io/quote v1.5.2
 )
 
@@ -62,6 +63,8 @@ golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c h1:pvCbr/wm8HzDD3fVywevekuf
 golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 gopkg.in/garbletest.v2 v2.999.0 h1:XHlBQi3MAcJL2fjNiEPAPAilkzc7hAv4vyyjY5w+IUY=
 gopkg.in/garbletest.v2 v2.999.0/go.mod h1:MI9QqKJD8i8oL8mW/bR0qq19/VuezEdJbVvl2B8Pa40=
+gopkg.in/garbletestconst.v2 v2.999.0 h1:VABqc63EJolbOSh1+WlSSQmX8ZT7VIs53mKCGxECTH8=
+gopkg.in/garbletestconst.v2 v2.999.0/go.mod h1:QA2FI8zGZhhsdLJGUrq78ah+ohEZo9ZDw3ex+C2WVEc=
 rsc.io/quote v1.5.2 h1:3fEykkD9k7lYzXqCYrwGAf7iNhbk4yCjHmKBN9td4L0=
 rsc.io/quote v1.5.2/go.mod h1:LzX7hefJvL54yjefDEDHNONDjII0t9xZLPXsUe+TKr0=
 rsc.io/sampler v1.3.0 h1:+lXbM7nYGGOYhnMEiMtjCwcUfjn4sajeMm15HMT6SnU=
@@ -73,11 +76,13 @@ package main
 
 import (
 	"fmt"
+	"database/sql"
 
 	"test/main/importedpkg"
 
 	"rsc.io/quote"
 	garbletest "gopkg.in/garbletest.v2"
+	garbletestconst "gopkg.in/garbletestconst.v2"
 )
 
 func main() {
@@ -90,6 +95,8 @@ func main() {
 
 	fmt.Println(quote.Go())
 	garbletest.Test()
+	fmt.Println(garbletestconst.StrConst)
+	fmt.Println(sql.Drivers()[0])
 }
 -- notag_fail.go --
 // +build !buildtag
@@ -159,3 +166,5 @@ imported const value
 x
 {3 {23} 0}
 Don't communicate by sharing memory, share memory by communicating.
+42
+dummy