cmd/fix: remove all functionality except for buildtag

For golang#73605

Change-Id: I4b46b5eb72471c215f2cc208c1b0cdd1fbdbf81a
Reviewed-on: https://go-review.googlesource.com/c/go/+/695855
Reviewed-by: Michael Matloob <[email protected]>
Reviewed-by: Michael Pratt <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>

Author: qiulaidongfeng

src/cmd/fix/cftype.go

@@ -6,9 +6,6 @@ package main
 
 import (
 	"go/ast"
-	"go/token"
-	"reflect"
-	"strings"
 )
 
 func init() {
@@ -18,130 +15,11 @@ func init() {
 var cftypeFix = fix{
 	name:     "cftype",
 	date:     "2017-09-27",
-	f:        cftypefix,
-	desc:     `Fixes initializers and casts of C.*Ref and JNI types`,
+	f:        noop,
+	desc:     `Fixes initializers and casts of C.*Ref and JNI types (removed)`,
 	disabled: false,
 }
 
-// Old state:
-//
-//	type CFTypeRef unsafe.Pointer
-//
-// New state:
-//
-//	type CFTypeRef uintptr
-//
-// and similar for other *Ref types.
-// This fix finds nils initializing these types and replaces the nils with 0s.
-func cftypefix(f *ast.File) bool {
-	return typefix(f, func(s string) bool {
-		return strings.HasPrefix(s, "C.") && strings.HasSuffix(s, "Ref") && s != "C.CFAllocatorRef"
-	})
-}
-
-// typefix replaces nil with 0 for all nils whose type, when passed to badType, returns true.
-func typefix(f *ast.File, badType func(string) bool) bool {
-	if !imports(f, "C") {
-		return false
-	}
-	typeof, _ := typecheck(&TypeConfig{}, f)
-	changed := false
-
-	// step 1: Find all the nils with the offending types.
-	// Compute their replacement.
-	badNils := map[any]ast.Expr{}
-	walk(f, func(n any) {
-		if i, ok := n.(*ast.Ident); ok && i.Name == "nil" && badType(typeof[n]) {
-			badNils[n] = &ast.BasicLit{ValuePos: i.NamePos, Kind: token.INT, Value: "0"}
-		}
-	})
-
-	// step 2: find all uses of the bad nils, replace them with 0.
-	// There's no easy way to map from an ast.Expr to all the places that use them, so
-	// we use reflect to find all such references.
-	if len(badNils) > 0 {
-		exprType := reflect.TypeFor[ast.Expr]()
-		exprSliceType := reflect.TypeFor[[]ast.Expr]()
-		walk(f, func(n any) {
-			if n == nil {
-				return
-			}
-			v := reflect.ValueOf(n)
-			if v.Kind() != reflect.Pointer {
-				return
-			}
-			if v.IsNil() {
-				return
-			}
-			v = v.Elem()
-			if v.Kind() != reflect.Struct {
-				return
-			}
-			for i := 0; i < v.NumField(); i++ {
-				f := v.Field(i)
-				if f.Type() == exprType {
-					if r := badNils[f.Interface()]; r != nil {
-						f.Set(reflect.ValueOf(r))
-						changed = true
-					}
-				}
-				if f.Type() == exprSliceType {
-					for j := 0; j < f.Len(); j++ {
-						e := f.Index(j)
-						if r := badNils[e.Interface()]; r != nil {
-							e.Set(reflect.ValueOf(r))
-							changed = true
-						}
-					}
-				}
-			}
-		})
-	}
-
-	// step 3: fix up invalid casts.
-	// It used to be ok to cast between *unsafe.Pointer and *C.CFTypeRef in a single step.
-	// Now we need unsafe.Pointer as an intermediate cast.
-	// (*unsafe.Pointer)(x) where x is type *bad -> (*unsafe.Pointer)(unsafe.Pointer(x))
-	// (*bad.type)(x) where x is type *unsafe.Pointer -> (*bad.type)(unsafe.Pointer(x))
-	walk(f, func(n any) {
-		if n == nil {
-			return
-		}
-		// Find pattern like (*a.b)(x)
-		c, ok := n.(*ast.CallExpr)
-		if !ok {
-			return
-		}
-		if len(c.Args) != 1 {
-			return
-		}
-		p, ok := c.Fun.(*ast.ParenExpr)
-		if !ok {
-			return
-		}
-		s, ok := p.X.(*ast.StarExpr)
-		if !ok {
-			return
-		}
-		t, ok := s.X.(*ast.SelectorExpr)
-		if !ok {
-			return
-		}
-		pkg, ok := t.X.(*ast.Ident)
-		if !ok {
-			return
-		}
-		dst := pkg.Name + "." + t.Sel.Name
-		src := typeof[c.Args[0]]
-		if badType(dst) && src == "*unsafe.Pointer" ||
-			dst == "unsafe.Pointer" && strings.HasPrefix(src, "*") && badType(src[1:]) {
-			c.Args[0] = &ast.CallExpr{
-				Fun:  &ast.SelectorExpr{X: &ast.Ident{Name: "unsafe"}, Sel: &ast.Ident{Name: "Pointer"}},
-				Args: []ast.Expr{c.Args[0]},
-			}
-			changed = true
-		}
-	})
-
-	return changed
+func noop(f *ast.File) bool {
+	return false
 }