go/gcimporter15: backport https://golang.org/cl/24648/

Change-Id: Id85050b236f5da2c705c45163c90fef1a396e8f8
Reviewed-on: https://go-review.googlesource.com/24700
Reviewed-by: Alan Donovan <adonovan@google.com>

go/gcimporter15/bexport.go

@@ -40,6 +40,9 @@ const debugFormat = false // default: false
 // If trace is set, debugging output is printed to std out.
 const trace = false // default: false
 
+// This version doesn't write the nointerface flag for exported methods.
+// The corresponding importer handles both "v0" and "v1".
+// See also issues #16243, #16244.
 const exportVersion = "v0"
 
 // trackAllTypes enables cycle tracking for all types, not just named

go/gcimporter15/bimport.go

@@ -26,6 +26,7 @@ type importer struct {
 	data    []byte
 	path    string
 	buf     []byte // for reading strings
+	version string
 
 	// object lists
 	strList       []string         // in order of appearance
@@ -75,8 +76,9 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 
 	// --- generic export data ---
 
-	if v := p.string(); v != "v0" {
-		return p.read, nil, fmt.Errorf("unknown export data version: %s", v)
+	p.version = p.string()
+	if p.version != "v0" && p.version != "v1" {
+		return p.read, nil, fmt.Errorf("unknown export data version: %s", p.version)
 	}
 
 	// populate typList with predeclared "known" types
@@ -344,6 +346,10 @@ func (p *importer) typ(parent *types.Package) types.Type {
 			params, isddd := p.paramList()
 			result, _ := p.paramList()
 
+			if p.version == "v1" {
+				p.int() // nointerface flag - discarded
+			}
+
 			sig := types.NewSignature(recv.At(0), params, result, isddd)
 			t0.AddMethod(types.NewFunc(pos, parent, name, sig))
 		}