cmd/compile: fix naming of types inside instantiations

Issues 47713 and 47877 were both due to problems with the names used for
instantiated functions/methods, which must be in sync with the names
used by types2.

 - Switched to using NameString() for writing out type arguments in
   instantiation names. This ensures that we are always adding the
   package to type names even for the local package. Previously, we were
   explicitly adding the package name for local packages, but that
   doesn't handle the case when the local type is embedded inside a
   pointer or slice type. By switching to NameString(), we fix #47713.

 - types1 and types2 write out 'interface {' differently (vs.
   'interface{') and we were already handling that. But we needed to add
   similar code to handle 'struct {' vs 'struct{'. This fixes issue
   #47877.

While fixing these bugs, I also moved some duplicated code (which
include some of the changes above) into a common function addTargs(). I
also moved InstType() name to subr.go, and renamed: MakeInstName ->
MakeFuncInstSym and MakeDictName -> MakeDictSym.

Also removed a couple of ".inst..inst." prefix checks which are
irrelvant now, since we don't add ".inst." anymore to function
instantiations.

Fixes #47713
Fixes #47877
Fixes #47922

Change-Id: I19e9a073451f3ababd8ec31b6608cd79ba8cba36
Reviewed-on: https://go-review.googlesource.com/c/go/+/344613
Trust: Dan Scales <danscales@google.com>
Reviewed-by: Keith Randall <khr@golang.org>

7 files changed, 115 insertions, 61 deletions

diff --git a/src/cmd/compile/internal/noder/stencil.go b/src/cmd/compile/internal/noder/stencil.go
index 570dec9990..602e88c102 100644
--- a/src/cmd/compile/internal/noder/stencil.go
+++ b/src/cmd/compile/internal/noder/stencil.go
@@ -590,7 +590,7 @@ func (g *irgen) getInstantiation(nameNode *ir.Name, shapes []*types.Type, isMeth
 		shapes = s1
 	}
 
-	sym := typecheck.MakeInstName(nameNode.Sym(), shapes, isMeth)
+	sym := typecheck.MakeFuncInstSym(nameNode.Sym(), shapes, isMeth)
 	info := g.instInfoMap[sym]
 	if info == nil {
 		// If instantiation doesn't exist yet, create it and add
@@ -1372,7 +1372,7 @@ func (g *irgen) getDictionarySym(gf *ir.Name, targs []*types.Type, isMeth bool)
 	}
 
 	// Get a symbol representing the dictionary.
-	sym := typecheck.MakeDictName(gf.Sym(), targs, isMeth)
+	sym := typecheck.MakeDictSym(gf.Sym(), targs, isMeth)
 
 	// Initialize the dictionary, if we haven't yet already.
 	lsym := sym.Linksym()
diff --git a/src/cmd/compile/internal/reflectdata/reflect.go b/src/cmd/compile/internal/reflectdata/reflect.go
index a95c76ff26..9b9efe04a2 100644
--- a/src/cmd/compile/internal/reflectdata/reflect.go
+++ b/src/cmd/compile/internal/reflectdata/reflect.go
@@ -1897,10 +1897,6 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy
 			} else {
 				targs = rcvr.RParams()
 			}
-			if strings.HasPrefix(ir.MethodSym(orig, method.Sym).Name, ".inst.") {
-				fmt.Printf("%s\n", ir.MethodSym(orig, method.Sym).Name)
-				panic("multiple .inst.")
-			}
 			// The wrapper for an auto-generated pointer/non-pointer
 			// receiver method should share the same dictionary as the
 			// corresponding original (user-written) method.
@@ -1929,7 +1925,7 @@ func methodWrapper(rcvr *types.Type, method *types.Field, forItab bool) *obj.LSy
 			}
 			targs = targs2
 
-			sym := typecheck.MakeInstName(ir.MethodSym(methodrcvr, method.Sym), targs, true)
+			sym := typecheck.MakeFuncInstSym(ir.MethodSym(methodrcvr, method.Sym), targs, true)
 			if sym.Def == nil {
 				// Currently we make sure that we have all the instantiations
 				// we need by generating them all in ../noder/stencil.go:instantiateMethods
@@ -2040,7 +2036,7 @@ func getDictionary(gf *types.Sym, targs []*types.Type) ir.Node {
 		}
 	}
 
-	sym := typecheck.MakeDictName(gf, targs, true)
+	sym := typecheck.MakeDictSym(gf, targs, true)
 
 	// Initialize the dictionary, if we haven't yet already.
 	if lsym := sym.Linksym(); len(lsym.P) == 0 {
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 2e3fdbc1bc..a1a3ac3e8a 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -8,7 +8,6 @@
 package typecheck
 
 import (
-	"bytes"
 	"encoding/binary"
 	"fmt"
 	"go/constant"
@@ -1751,32 +1750,6 @@ func builtinCall(pos src.XPos, op ir.Op) *ir.CallExpr {
 	return ir.NewCallExpr(pos, ir.OCALL, ir.NewIdent(base.Pos, types.BuiltinPkg.Lookup(ir.OpNames[op])), nil)
 }
 
-// InstTypeName creates a name for an instantiated type, based on the name of the
-// generic type and the type args.
-func InstTypeName(name string, targs []*types.Type) string {
-	b := bytes.NewBufferString(name)
-	b.WriteByte('[')
-	for i, targ := range targs {
-		if i > 0 {
-			b.WriteByte(',')
-		}
-		// WriteString() does not include the package name for the local
-		// package, but we want it to make sure type arguments (including
-		// type params) are uniquely specified.
-		if targ.Sym() != nil && targ.Sym().Pkg == types.LocalPkg {
-			b.WriteString(targ.Sym().Pkg.Name)
-			b.WriteByte('.')
-		}
-		// types1 uses "interface {" and types2 uses "interface{" - convert
-		// to consistent types2 format.
-		tstring := targ.String()
-		tstring = strings.Replace(tstring, "interface {", "interface{", -1)
-		b.WriteString(tstring)
-	}
-	b.WriteByte(']')
-	return b.String()
-}
-
 // NewIncompleteNamedType returns a TFORW type t with name specified by sym, such
 // that t.nod and sym.Def are set correctly.
 func NewIncompleteNamedType(pos src.XPos, sym *types.Sym) *types.Type {
@@ -1879,7 +1852,7 @@ func substInstType(t *types.Type, baseType *types.Type, targs []*types.Type) {
 		}
 		t2 := msubst.Typ(f.Type)
 		oldsym := f.Nname.Sym()
-		newsym := MakeInstName(oldsym, targs, true)
+		newsym := MakeFuncInstSym(oldsym, targs, true)
 		var nname *ir.Name
 		if newsym.Def != nil {
 			nname = newsym.Def.(*ir.Name)
diff --git a/src/cmd/compile/internal/typecheck/subr.go b/src/cmd/compile/internal/typecheck/subr.go
index c7a3718b31..7ae10ef406 100644
--- a/src/cmd/compile/internal/typecheck/subr.go
+++ b/src/cmd/compile/internal/typecheck/subr.go
@@ -900,6 +900,35 @@ func TypesOf(x []ir.Node) []*types.Type {
 	return r
 }
 
+// addTargs writes out the targs to buffer b as a comma-separated list enclosed by
+// brackets.
+func addTargs(b *bytes.Buffer, targs []*types.Type) {
+	b.WriteByte('[')
+	for i, targ := range targs {
+		if i > 0 {
+			b.WriteByte(',')
+		}
+		// Use NameString(), which includes the package name for the local
+		// package, to make sure that type arguments (including type params),
+		// are uniquely specified.
+		tstring := targ.NameString()
+		// types1 uses "interface {" and types2 uses "interface{" - convert
+		// to consistent types2 format.  Same for "struct {"
+		tstring = strings.Replace(tstring, "interface {", "interface{", -1)
+		tstring = strings.Replace(tstring, "struct {", "struct{", -1)
+		b.WriteString(tstring)
+	}
+	b.WriteString("]")
+}
+
+// InstTypeName creates a name for an instantiated type, based on the name of the
+// generic type and the type args.
+func InstTypeName(name string, targs []*types.Type) string {
+	b := bytes.NewBufferString(name)
+	addTargs(b, targs)
+	return b.String()
+}
+
 // makeInstName1 returns the name of the generic function instantiated with the
 // given types, which can have type params or shapes, or be concrete types. name is
 // the name of the generic function or method.
@@ -912,36 +941,16 @@ func makeInstName1(name string, targs []*types.Type, hasBrackets bool) string {
 	} else {
 		b.WriteString(name)
 	}
-	b.WriteString("[")
-	for i, targ := range targs {
-		if i > 0 {
-			b.WriteString(",")
-		}
-		// WriteString() does not include the package name for the local
-		// package, but we want it for uniqueness.
-		if targ.Sym() != nil && targ.Sym().Pkg == types.LocalPkg {
-			b.WriteString(targ.Sym().Pkg.Name)
-			b.WriteByte('.')
-		}
-		// types1 uses "interface {" and types2 uses "interface{" - convert
-		// to consistent types2 format.
-		tstring := targ.String()
-		tstring = strings.Replace(tstring, "interface {", "interface{", -1)
-		b.WriteString(tstring)
-	}
-	b.WriteString("]")
+	addTargs(b, targs)
 	if i >= 0 {
 		i2 := strings.LastIndex(name[i:], "]")
 		assert(i2 >= 0)
 		b.WriteString(name[i+i2+1:])
 	}
-	if strings.HasPrefix(b.String(), ".inst..inst.") {
-		panic(fmt.Sprintf("multiple .inst. prefix in %s", b.String()))
-	}
 	return b.String()
 }
 
-// MakeInstName makes the unique name for a stenciled generic function or method,
+// MakeFuncInstSym makes the unique sym for a stenciled generic function or method,
 // based on the name of the function fnsym and the targs. It replaces any
 // existing bracket type list in the name. MakeInstName asserts that fnsym has
 // brackets in its name if and only if hasBrackets is true.
@@ -953,11 +962,11 @@ func makeInstName1(name string, targs []*types.Type, hasBrackets bool) string {
 //
 // The standard naming is something like: 'genFn[int,bool]' for functions and
 // '(*genType[int,bool]).methodName' for methods
-func MakeInstName(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
+func MakeFuncInstSym(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
 	return gf.Pkg.Lookup(makeInstName1(gf.Name, targs, hasBrackets))
 }
 
-func MakeDictName(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
+func MakeDictSym(gf *types.Sym, targs []*types.Type, hasBrackets bool) *types.Sym {
 	for _, targ := range targs {
 		if targ.HasTParam() {
 			fmt.Printf("FUNCTION %s\n", gf.Name)
@@ -1222,7 +1231,7 @@ func (ts *Tsubster) Typ(t *types.Type) *types.Type {
 		for i, f := range t.Methods().Slice() {
 			t2 := ts.Typ(f.Type)
 			oldsym := f.Nname.Sym()
-			newsym := MakeInstName(oldsym, ts.Targs, true)
+			newsym := MakeFuncInstSym(oldsym, ts.Targs, true)
 			var nname *ir.Name
 			if newsym.Def != nil {
 				nname = newsym.Def.(*ir.Name)
diff --git a/test/typeparam/issue47713.go b/test/typeparam/issue47713.go
new file mode 100644
index 0000000000..a38eea19eb
--- /dev/null
+++ b/test/typeparam/issue47713.go
@@ -0,0 +1,52 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"encoding"
+	"fmt"
+)
+
+type Seralizable interface {
+	encoding.BinaryMarshaler
+	encoding.BinaryUnmarshaler
+}
+
+type SerDeString string
+
+func (s *SerDeString) UnmarshalBinary(in []byte) error {
+	*s = SerDeString(in)
+	return nil
+}
+
+func (s SerDeString) MarshalBinary() ([]byte, error) {
+	return []byte(s), nil
+}
+
+
+type GenericSerializable[T Seralizable] struct {
+	Key string
+	Value T
+}
+
+func (g GenericSerializable[T]) Send() {
+	out, err := g.Value.MarshalBinary()
+	if err != nil {
+		panic("bad")
+	}
+	var newval SerDeString
+	newval.UnmarshalBinary(out)
+	fmt.Printf("Sent %s\n", newval)
+}
+
+func main() {
+	val := SerDeString("asdf")
+	x := GenericSerializable[*SerDeString]{
+		Value: &val,
+	}
+	x.Send()
+}
diff --git a/test/typeparam/issue47713.out b/test/typeparam/issue47713.out
new file mode 100644
index 0000000000..a6e77197d8
--- /dev/null
+++ b/test/typeparam/issue47713.out
@@ -0,0 +1 @@
+Sent asdf
diff --git a/test/typeparam/issue47877.go b/test/typeparam/issue47877.go
new file mode 100644
index 0000000000..0a834590dd
--- /dev/null
+++ b/test/typeparam/issue47877.go
@@ -0,0 +1,23 @@
+// run -gcflags=-G=3
+
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type Map[K comparable, V any] struct {
+        m map[K]V
+}
+
+func NewMap[K comparable, V any]() Map[K, V] {
+        return Map[K, V]{m: map[K]V{}}
+}
+
+func (m Map[K, V]) Get(key K) V {
+        return m.m[key]
+}
+
+func main() {
+        _ = NewMap[int, struct{}]()
+}