cmd/compile: move typepkg to package types

Response to code review feedback on CL 40693.

It is now only accessible by types.TypePkgLookup.

Passes toolstash-check.

Change-Id: I0c422c1a271f97467ae38de53af9dc33f4b31bdb
Reviewed-on: https://go-review.googlesource.com/41304
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

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

@@ -114,8 +114,6 @@ var racepkg *types.Pkg // package runtime/race
 
 var msanpkg *types.Pkg // package runtime/msan
 
-var typepkg *types.Pkg // fake package for runtime type info (headers)
-
 var unsafepkg *types.Pkg // package unsafe
 
 var trackpkg *types.Pkg // fake package for field tracking

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

@@ -150,8 +150,6 @@ func Main(archInit func(*Arch)) {
 	trackpkg = types.NewPkg("go.track", "go.track")
 	trackpkg.Prefix = "go.track" // not go%2etrack
 
-	typepkg = types.NewPkg("type", "type")
-
 	// pseudo-package used for map zero values
 	mappkg = types.NewPkg("go.map", "go.map")
 	mappkg.Prefix = "go.map"

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

@@ -908,7 +908,7 @@ func typesymname(t *types.Type) string {
 }
 
 func typesym(t *types.Type) *types.Sym {
-	return typepkg.Lookup(typesymname(t))
+	return types.TypePkgLookup(typesymname(t))
 }
 
 // tracksym returns the symbol for tracking use of field/method f, assumed
@@ -919,7 +919,7 @@ func tracksym(t *types.Type, f *types.Field) *types.Sym {
 
 func typesymprefix(prefix string, t *types.Type) *types.Sym {
 	p := prefix + "." + t.ShortString()
-	s := typepkg.Lookup(p)
+	s := types.TypePkgLookup(p)
 
 	//print("algsym: %s -> %+S\n", p, s);
 
@@ -1561,7 +1561,7 @@ func dalgsym(t *types.Type) *types.Sym {
 		// we use one algorithm table for all AMEM types of a given size
 		p := fmt.Sprintf(".alg%d", t.Width)
 
-		s = typepkg.Lookup(p)
+		s = types.TypePkgLookup(p)
 
 		if s.AlgGen() {
 			return s
@@ -1571,7 +1571,7 @@ func dalgsym(t *types.Type) *types.Sym {
 		// make hash closure
 		p = fmt.Sprintf(".hashfunc%d", t.Width)
 
-		hashfunc = typepkg.Lookup(p)
+		hashfunc = types.TypePkgLookup(p)
 
 		ot := 0
 		ot = dsymptr(hashfunc, ot, Runtimepkg.Lookup("memhash_varlen"), 0)
@@ -1581,7 +1581,7 @@ func dalgsym(t *types.Type) *types.Sym {
 		// make equality closure
 		p = fmt.Sprintf(".eqfunc%d", t.Width)
 
-		eqfunc = typepkg.Lookup(p)
+		eqfunc = types.TypePkgLookup(p)
 
 		ot = 0
 		ot = dsymptr(eqfunc, ot, Runtimepkg.Lookup("memequal_varlen"), 0)

src/cmd/compile/internal/types/pkg.go

@@ -68,6 +68,13 @@ var nopkg = &Pkg{
 	Syms: make(map[string]*Sym),
 }
 
+// fake package for runtime type info (headers)
+var typepkg = NewPkg("type", "type")
+
+func TypePkgLookup(name string) *Sym {
+	return typepkg.Lookup(name)
+}
+
 func (pkg *Pkg) Lookup(name string) *Sym {
 	s, _ := pkg.LookupOK(name)
 	return s