cmd/compile: don't lose //go:nointerface pragma in export data

Fixes #16243.

Change-Id: I207d1e8aa48abe453a23c709ccf4f8e07368595b
Reviewed-on: https://go-review.googlesource.com/24648
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/compile/internal/gc/bexport.go

@@ -153,7 +153,13 @@ const debugFormat = false // default: false
 // TODO(gri) disable and remove once there is only one export format again
 const forceObjFileStability = true
 
-const exportVersion = "v0"
+// Supported export format versions.
+// TODO(gri) Make this more systematic (issue #16244).
+const (
+	exportVersion0 = "v0"
+	exportVersion1 = "v1"
+	exportVersion  = exportVersion1
+)
 
 // exportInlined enables the export of inlined function bodies and related
 // dependencies. The compiler should work w/o any loss of functionality with
@@ -727,6 +733,14 @@ func (p *exporter) typ(t *Type) {
 			p.paramList(sig.Params(), inlineable)
 			p.paramList(sig.Results(), inlineable)
 
+			// for issue #16243
+			// We make this conditional for 1.7 to avoid consistency problems
+			// with installed packages compiled with an older version.
+			// TODO(gri) Clean up after 1.7 is out (issue #16244)
+			if exportVersion == exportVersion1 {
+				p.bool(m.Nointerface)
+			}
+
 			var f *Func
 			if inlineable {
 				f = mfn.Func

src/cmd/compile/internal/gc/bimport.go

@@ -21,8 +21,9 @@ import (
 // changes to bimport.go and bexport.go.
 
 type importer struct {
-	in  *bufio.Reader
-	buf []byte // reused for reading strings
+	in      *bufio.Reader
+	buf     []byte // reused for reading strings
+	version string
 
 	// object lists, in order of deserialization
 	strList       []string
@@ -67,8 +68,9 @@ func Import(in *bufio.Reader) {
 
 	// --- generic export data ---
 
-	if v := p.string(); v != exportVersion {
-		Fatalf("importer: unknown export data version: %s", v)
+	p.version = p.string()
+	if p.version != exportVersion0 && p.version != exportVersion1 {
+		Fatalf("importer: unknown export data version: %s", p.version)
 	}
 
 	// populate typList with predeclared "known" types
@@ -432,10 +434,15 @@ func (p *importer) typ() *Type {
 			params := p.paramList()
 			result := p.paramList()
 
+			nointerface := false
+			if p.version == exportVersion1 {
+				nointerface = p.bool()
+			}
+
 			n := methodname1(newname(sym), recv[0].Right)
 			n.Type = functype(recv[0], params, result)
 			checkwidth(n.Type)
-			addmethod(sym, n.Type, tsym.Pkg, false, false)
+			addmethod(sym, n.Type, tsym.Pkg, false, nointerface)
 			p.funcList = append(p.funcList, n)
 			importlist = append(importlist, n)
 

src/cmd/compile/internal/gc/builtin.go

@@ -3,7 +3,7 @@
 package gc
 
 const runtimeimport = "" +
-	"cn\x00\x03v0\x01\rruntime\x00\t\x11newobject\x00\x02\x17\"\vtyp·2\x00\x00" +
+	"cn\x00\x03v1\x01\rruntime\x00\t\x11newobject\x00\x02\x17\"\vtyp·2\x00\x00" +
 	"\x01\x17:\x00\t\x13panicindex\x00\x00\x00\t\x13panicslice\x00\x00\x00\t\x15pani" +
 	"cdivide\x00\x00\x00\t\x15throwreturn\x00\x00\x00\t\x11throwinit\x00\x00\x00" +
 	"\t\x11panicwrap\x00\x05 \x00 \x00 \x00\x00\t\rgopanic\x00\x01\x1b\x00\x00\x00\x00\t\x11go" +
@@ -105,6 +105,6 @@ const runtimeimport = "" +
 	"\x01\x02\v\x00\x01\x00\n$$\n"
 
 const unsafeimport = "" +
-	"cn\x00\x03v0\x01\vunsafe\x00\x05\r\rPointer\x00\x16\x00\t\x0fOffsetof\x00\x01" +
+	"cn\x00\x03v1\x01\vunsafe\x00\x05\r\rPointer\x00\x16\x00\t\x0fOffsetof\x00\x01" +
 	":\x00\x01\x16\x00\t\vSizeof\x00\x01:\x00\x01\x16\x00\t\rAlignof\x00\x01:\x00\x01\x16\x00\v\b\x00\v" +
 	"\x00\x01\x00\n$$\n"

src/cmd/compile/internal/gc/parser.go

@@ -2006,7 +2006,8 @@ func (p *parser) hidden_fndcl() *Node {
 		ss.Type = functype(s2[0], s6, s8)
 
 		checkwidth(ss.Type)
-		addmethod(s4, ss.Type, p.structpkg, false, false)
+		addmethod(s4, ss.Type, p.structpkg, false, p.pragma&Nointerface != 0)
+		p.pragma = 0
 		funchdr(ss)
 
 		// inl.C's inlnode in on a dotmeth node expects to find the inlineable body as

src/go/internal/gcimporter/bimport.go

@@ -21,6 +21,7 @@ type importer struct {
 	data    []byte
 	path    string
 	buf     []byte // for reading strings
+	version string
 
 	// object lists
 	strList       []string         // in order of appearance
@@ -66,8 +67,9 @@ func BImportData(imports map[string]*types.Package, data []byte, path string) (i
 
 	// --- 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
@@ -304,6 +306,10 @@ 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(token.NoPos, parent, name, sig))
 		}